Introduction

The Apogee Groove is a very good sounding “dongle” DAC/amp that replaces a desktop stack for many. It draws its current from the source device and has a rather high output impedance of 20 ohm (the competition is typically < 1 ohm), which makes it problematic for use with low-impedance iems. The manufacturer does not recommend using it with multidriver iems either.

Whilst the laws of physics appear to limit the Apogee Groove’s use, there are some welcome exceptions to the rule(s)…which will be discussed in the following.

General Considerations

The 1/8 Rule

If you multiply the output impedance of your source by eight, that’s the lowest impedance headphones you should use with that source. For example, the Apogee Groove with its 20 ohm output impedance should be paired with  >160 ohm headphones.

What if the Output Impedance violates the 1/8 Rule? 

There will be variations in the headphone’s frequency response. With some headphones, especially balanced armature or multi driver designs, these variations can be rather extreme. Typical is bloated, boomy bass as the headphone does not get enough power.

Why are BA Drivers problematic (Multis and even single BAs)? 

With some headphones, especially balanced armature or multidriver designs, these variations can be rather extreme. Example: these headphones usually have a rated impedance between 16 and 32 ohm but their actual impedance typically varies greatly with frequency. The 21 ohm Ultimate Ears SuperFi 5, for example, ranges from 10 ohms to 90 ohms. These wide variations frequently interact in unfavourable ways with the output Impedance of the source. 

What about single DD Drivers? 

The impedance variations across the frequency spectrum are not as severe as with BAs…or there is no variation at all.

Apogee Groove only

What is different for the Apogee Groove with single DDs?

The 1/8 rule can be disregarded for single DDs with the Apogee Groove, thanks to Apogee’s special “Constant Current Drive” tech, and not even “in every single pair case”.  The CCD technology compensates for impedance mismatches between source and headphones. Without CCD tech all sub 100 ohm drivers you’d connect would have a very noticeable mid bass bump. Apogee Groove won’t alter FR when driving low impedance loads, or higher impedance ones featuring wild impedance swings.

What is different for the Apogee Groove with BAs and Multidrivers?

We would expect the Groove’s high output impedance to alter the BA’s/multidrivers’ frequency responses.

Apogee themselves advise against the use of multidriver BAs and crossover networks as their “Constant Current Drive” technology may result in uneven frequency response when used with certain models.”

Their impedance mismatch compensation does not work with many multidriver BAs. But why? 

There may be a conflict between crossover filters (using capacitors) and CCD. The technology may work with non-capacitive filters …or some other trick. 

I speculate the the Groove has a better chance of compensating for impedance variations in BAs, if these are not extravagant. Would be interesting to compare the impedance profiles of such BAs that work and some that don’t.

BUT: unless you compare frequency responses measured using Apogee Groove against a low-impedance amp, you don’t know wether your frequency response was skewed, as the deviations may not be that audibly obvious in some cases…considering our generally poor auditory memory and our expectation bias.

Hope this all makes sense to you.

Until next time…keep on listening!

Sources used

Discussion with Alberto and Kazi. Photos by Kazi.

http://nwavguy.blogspot.com/2011/02/headphone-impedance-explained.html

http://nwavguy.blogspot.com/2011/02/headphone-amp-impedance.html

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The post The 1/8 Rule And The Apogee Groove – A Tech Discussion appeared first on Audio Reviews.

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The eartips are listed in alphabetical order.

Latest Additions

May 2022 additions: Acoustune AEX07, Acoustune AEX50, Azla SednaEarFit Vivid Edition.

Mar 2022 additions: Simphonio Diamond Earfit, Softears Liquid Silicone Ear Tips.

Feb 2022 additions: Canyon Silikon-Eartips ET400 (Bass), ALPEX Hi-Unit HSE-A1000.

Testing Parameters and Disclaimer

The following tests of silicone eartips are based on my evaluations and listening observations. All test are conducted in a quiet listening environment. Fit is ensured such that eartips are properly inserted and seated into the ear canal with good seal. I have to elaborate, your experiences may vary.

Associated equipment list: Sources – JWD JWM-115, Shanling M0, Zishan DSD and Topping DX3 Pro.IEMs – Tin Hifi T2, KBEAR Diamond, TRI I4 and Moondrop Kanas Pro

Disclaimer: All scores are subjected to change without notice. I may update or add new scores every few months when I acquire new eartips.

NOTE: I don’t have favorite eartips but if I want neutrality, SpinFits CP-145 is my first pick usually. For IEM tuning, I always use reversed KZ Starline, follow by stock eartips from the manufacturer. 

A

Acoustune AEX07

Bore size: regular
Stem length: regular
Feel: sturdy and firm
Bass: 3.50
Midrange: 5.00
Treble: 4.25
Soundstage: 3.75
Vocal presence: 4.00

For neutral tonality with emphasis in midrange. The AEX07 sounds closer to AET07a than AET07. Improved overall tonal texture and clarity over the latter. Note weight is is denser than AET07a however it sounds less congested than AET07. A good middle-ground between its two predecessors. My new favorite Acoustune eartip.

Purchased from MTMT Audio, Hong Kong.

Acoustune AEX50

Bore size: wide
Stem length: regular 
Feel: soft and sturdy
Bass: 1.50
Midrange: 2.50
Treble: 4.25
Soundstage: 3.75
Vocal presence: 3.50

What was Acoustune thinking when they came out these?! 

These eartips are “directional” (meaning you must wear them in a certain way) and a pain in the butt to put on. You need lots of patience and time to get them to sit well inside the ears. Getting the proper “ear seal” is nearly impossible. There is literally zero isolation. The design adopts a WW2 helmet-like umbrella shape with double “wings” design. The wide wing is to face the inner-part of the entrance to the ear canal, and the narrow wing facing out (see attached photos). 

Unfortunately, I couldn’t get them to fit in my ears properly not matter how hard I tried. Although made of soft memory polymer, they become uncomfortable, irritating and warm inside my ears after a while.

Sound-wise, these eartips thin the sound so much that they make your TOTL IEMs sound like 1950s transistor radio. Everything sounds distant, lean and sibilance. 

Purchased from MTMT Audio, Hong Kong.

Acoustune AET06
Bore size: double flange, regular
Stem length: extremely short
Feel: firm and sturdy
Bass: 5.0
Midrange: 5
Treble: 4
Soundstage: 3.75
Vocal presence: 5
Similar to AET08 in many ways but with an even tighter bass punch. Vocal is bodied and three-dimensional
Purchased from MTMT Audio, Hong Kong.

Acoustune AET06a (Enhanced comfort)
Bore size: double flange, regular
Stem length: extremely short
Feel: firm and pliable (slightly softer than AET06a)
Bass: 4.75
Midrange: 5
Treble: 4.25
Soundstage: 3.75
Vocal presence: 5
Virtually identical to AET06 with a hair bit cleaner and more sparkling upper-midrange and treble. Feels softer than AET06 thus less pressure inside the ears.
Purchased from MTMT Audio, Hong Kong.

Acoustune AET07
Bore size: regular
Stem length: regular
Feel: sturdy and firm
Bass: 3.75
Midrange: 5
Treble: 4
Soundstage: 3.5
Vocal presence: 4
For neutral tonality with emphasis in midrange. Similar to SpinFit CP-145 in many ways but with better bass texture and vocal presence.
Purchased from Japan through a friend

Acoustune AET07a
Bore size: regular
Stem length: regular
Feel: sturdy and firm
Bass: 3.75
Midrange: 5
Treble: 4
Soundstage: 3.5
Vocal presence: 4.25
Slight improvement over Acoustune AET07 in texture, detail, tonal purity and vocal clarity.
Purchased from MTMT Audio, Hong Kong

Acoustune AET08
Bore size: regular
Stem length: regular
Feel: firm and sturdy
Bass: 4.5
Midrange: 5
Treble: 3.5
Soundstage: 3.5
Vocal presence: 5
For vocal, midrange and solid bass
Purchased from Japan through a friend

Acoustune AEX07

Bore size: regular
Stem length: regular
Feel: sturdy and firm
Bass: 3.50
Midrange: 5.00
Treble: 4.25
Soundstage: 3.75
Vocal presence: 4.00

For neutral tonality with emphasis in midrange. The AEX07 sounds closer to AET07a than AET07. Improved overall tonal texture and clarity over the latter. Note weight is is denser than AET07a however it sounds less congested than AET07. A good middle-ground between its two predecessors. My new favorite Acoustune eartip.

Purchased from MTMT Audio, Hong Kong.

Acoustune AEX50

Bore size: wide
Stem length: regular 
Feel: soft and sturdy
Bass: 1.50
Midrange: 2.50
Treble: 4.25
Soundstage: 3.75
Vocal presence: 3.50

What was Acoustune thinking when they came out these?! 

These eartips are “directional” (meaning you must wear them in a certain way) and a pain in the butt to put on. You need lots of patience and time to get them to sit well inside the ears. Getting the proper “ear seal” is nearly impossible. There is literally zero isolation. The design adopts a WW2 helmet-like umbrella shape with double “wings” design. The wide wing is to face the inner-part of the entrance to the ear canal, and the narrow wing facing out (see attached photos). 

Unfortunately, I couldn’t get them to fit in my ears properly not matter how hard I tried. Although made of soft memory polymer, they become uncomfortable, irritating and warm inside my ears after a while.

Sound-wise, these eartips thin the sound so much that they make your TOTL IEMs sound like 1950s transistor radio. Everything sounds distant, lean and sibilance. 

Purchased from MTMT Audio, Hong Kong.

ADV Eartune Fidelity U Elliptical Silicone Eartips (horizontal fit)
Bore size: small (4mm)
Stem length: short
Feel: flexible, soft and pliable
Bass: 3.5
Midrange: 4
Treble: 3.5
Soundstage: 2.5
Vocal presence: 3.5
An interesting elliptical eartip which fits two ways and can affect sound. The not so interesting part is it projects a smaller soundstage and vocals get thrown backwards. In both fittings, I experienced quite significant treble roll-off and details lost. Isolation is NOT GOOD!
Sample from ADVSound, courtesy of co-blogger Baskingshark.

ADV Eartune Fidelity U Elliptical Silicone Eartips (vertical fit)
Bore size: small (4mm)
Stem length: short
Feel: flexible, soft and pliable
Bass: 3.0
Midrange: 3.5
Treble: 3.5
Soundstage: 2.5
Vocal presence: 3.5
An interesting elliptical eartip which fits two ways and can affect sound. The not so interesting part is it projects a smaller soundstage and vocals get thrown backwards. In both fittings, I experienced quite significant treble roll-off and details lost. Isolation is NOT GOOD!
Sample from ADVSound, courtesy of co-blogger Baskingshark.

AKG Anti-allergenic Sleeves for K3003
Bore size: regular
Stem length: regular
Feel: soft and firm
Bass: 4.25
Midrange: 5.0
Treble: 4
Soundstage: 3.75
Vocal presence: 5.0
Yes, it is called “anti-allergenic sleeves”. If you can find these at your local earphone stores, GET IT! These sound extremely close to Azla SednaEarFit XELASTEC but at half the cost. If you are not used to the grippiness or tackiness of the XELASTEC, AKG is the best alternative. Vocal is forward with very good dimension and ambience. 3D. Best of all it doesn’t affect bass and treble.
Purchase from a friend who bought from AKG outlet in Germany

ALPEX Hi-Unit HSE-A1000
Bore size: wide
Stem length: short
Feel: soft and pliable
Bass: 4.25
Midrange: 4.25
Treble: 4.50
Soundstage: 4.0
Vocal presence: 4.25
These wide bore eartips bear an uncanny resemblance to JVC Spiral Dot in look but they don’t sound alike. The HSE-A1000 is brighter, more open and livelier. Midrange has more sparkle and life. The bass is cleaner, tighter and more textured. Best of all, they cost only a fraction of the JVC. I am surprised how good these are. What a hidden gem!
Purchased from Amazon Japan

Audiosense S400 Soft Silicone Eartips
Bore size: regular
Stem length: short
Feel: flexible and firm
Bass: 4.25
Midrange: 5.0
Treble: 4.0
Soundstage: 4.0
Vocal presence: 4.5
Both Baskingshark and Vannak Pech are fans of this eartip. It adds “round-meatiness” (a.k.a smoothness and body) to the music without clouding the low-mids. Vocals can be a tad forward but still very pleasant. I would rank its sonic signatures between SpinFit CP-145 and Final Audio Type E eartips. Similar to SpinFits, it has a pivoting cap design.
Purchased from Audiosense Official Store on AliExpress

Audio-Technica FineFit ER-CKM55M
Bore size: small
Stem length: regular
Feel: soft and flrm
Bass: 4
Midrange: 4.5
Treble: 3.5
Soundstage: 3
Vocal presence: 4
Bassy eartips that accentuates on vocal. Soundstage is smaller than most tips.
Purchased from Stereo Electronics (Singapore)

Azla SednaEarFit Crystal (Standard)

Bore size: regular
Stem length: regular
Feel: soft, grippy and sticky
Bass: 3.5
Midrange: 5.0
Treble: 4.25
Soundstage: 4.0
Vocal presence: 5.0

Another pricey eartip offering from Azla. Feels just like XELASTEC. Both XELASTEC and Crystal excel in the midrange and vocals. Their most obvious differences are in the upper-mids and mid-bass range where Crystal adds a touch more instrument presence, separation and space. Mid-bass is cleaner and clearer than XELASTEC yet doesn’t sacrifice warmth and body. It is good to note that Crystal does not have the upper-midrange “ringing” that plagues XELASTEC.
Purchased from Amazon Japan

Azla SednaEarfit Crystal (for TWS)
Bore size: regular
Stem length: short
Feel: soft, grippy and sticky
Bass: 3.5
Midrange: 5.0
Treble: 4.25
Soundstage: 4.0
Vocal presence: 5.0

Another pricey eartip offering from Azla. Feels similar to XELASTEC but with a shallower in-ear fit. Both XELASTEC and Crystal excel in the midrange and vocals. Their most obvious differences are in the upper-mids and mid-bass range where Crystal adds a touch more instrument presence, separation and space. Mid-bass is cleaner and clearer than XELASTEC yet doesn’t sacrifice warmth and body. It is good to note that Crystal does not have the upper-midrange “ringing” that plagues XELASTEC. Can be used for both IEM and TWS.

Purchased from MTMT Audio, Hong Kong

Azla Sedna EarFit (Regular)
Bore size: wide
Stem length: long
Feel: sturdy and very firm
Bass: 4
Midrange: 4.5
Treble: 4
Soundstage: 3.75
Vocal presence: 4.5
For long nozzle good midrange
Purchased from Amazon Japan

Azla Sedna EarFit (Light)
Bore size: wide
Stem length: long
Feel: sturdy and very firm
Bass: 3.75
Midrange: 4
Treble: 3.5
Soundstage: 3.75
Vocal presence: 4.25
A “lighter” version of the regular Sedna EarFit. More balanced-sounding overall.
Purchased from Amazon Japan

Azla SednaEarFit (Light) Short
Bore size: wide
Stem length: regular
Feel: sturdy and very firm
Bass: 3.75
Midrange: 4.25
Treble: 3.75
Soundstage: 3.75
Vocal presence: 4.5
A “short-stem” version of SednaEarFitLight. Both nozzles are brought closer to the eardrums thus enhancement in overall clarity and vocal presence, which means stereo image and presentation are slightly more forward.
Purchased from MTMT Audio, Hong Kong

Azla SednaEarFit Vivid Edition

Bore size: narrow 
Stem length: regular
Feel: sturdy and very firm
Bass: 4.25
Midrange: 4.50
Treble: 4.25
Soundstage: 3.75
Vocal presence: 4.75

At first glance, these look like colourful version of SednaEarFitLight Short. Upon close examination, they are very different in looks, feel and sound. SednaEarFit Vivid Edition feels softer and plusher. It has a narrower bore and sounds livelier than SednaEarFit Light Short. Bass is punchier, better texture and definition. Vocals sound cleaner, clearer and slightly forward. Upper-registers are brighter and slightly more extended than SednaEarFitLight Short. This eartips definitely deserve the “Vivid Edition” title. Not suitable for bright or shouty IEMs. 

Purchased from MTMT Audio, Hong Kong

Azla SednaEarFit XELASTEC
Bore size: regular
Stem length: regular
Feel: soft, grippy and sticky
Bass: 4.0
Midrange: 5.0
Treble: 3.75
Soundstage: 3.50
Vocal presence: 5.0

The most expensive eartip in my collection. Isolation is impeccable. If you love vocals, THIS IS IT! Vocal presence is extremely 3D. Best of all it doesn’t affect bass and treble. Projects soundstage a bit narrower than regular SednaEarFit.

B

BGVP A07 Eartips
Bore size: regular
Stem length: regular
Feel: sturdy and firm
Bass: 3.75
Midrange: 5
Treble: 4
Soundstage: 3.5
Vocal presence: 4.25
Suspiciously similar to Acoustune AET07. Heck… It sounds closer to AET07a than AET07. Neutral tonality with emphasis in midrange and top-end sparkle. I find this eartip to have better bass texture, dynamics and vocal presence than SpinFit CP100 and CP145. The A07 is often labeled as “vocal” eartip for most stock tips offering.Purchased from BGVP Taobao store

BGVP A08 Eartips
Bore size: regular
Stem length: regular
Feel: firm and sturdy
Bass: 4.5
Midrange: 5
Treble: 3.5
Soundstage: 3.5
Vocal presence: 5
Suspiciously similar to Acoustune AET08, this eartip adds thickness to bass and midrange. However, unlike Acoustune AET08, I find it a speck bright. The A08 is often labeled as “bass” eartip for most stock tips offering.Purchased from BGVP Taobao store

BGVP Electric Blue “ArtMagic VG4” Silicone Vocal Eartip
Bore size: regular 
Stem length: regular
Feel: soft and flexible
Bass: 3.5
Midrange: 5.0
Treble: 4.25
Soundstage: 4.0
Vocal presence: 4.0This eartip comes stock with BGVP ArtMagic VG4, ArtMagic V12 and DH3, labeled under “vocal” eartip. Highly-praised by Singaporean audiophile Reza Emmanuel as his standard reference, I must say this eartip is extremely comfortable, literally fatigue-free for long listening sessions.

Sound is clean, tight and very well-textured. Bass and low-mids are detailed, punchy and dynamic. Midrange is clear with excellent separation. Upper-mids and treble are smooth and extended with good amount of air and spacial cues. Vocal position is ‘just nice” – that is neither too forward nor too laid-back. Soundstage is realistically wide without sounding too spread-out. Similar to SpinFit, this eartip comes with a pivoting umbrella/cap.
Specially-ordered from BGVP Taobao Official Store as they do not sell this eartip individually. 

BGVP E01 Eartips
Bore size: regular
Stem length: regular
Feel: soft and sturdy
Bass: 4
Midrange: 5
Treble: 3.75
Soundstage: 4
Vocal presence: 4
Looks identical to Final Audio Type E eartips it has a balanced sound that tames harshness. I find it lacks the smoothness of original Final Audio Type E eartips. This style of eartip is often labeled as “balance” eartip for most stock tips offering.Purchased from BGVP Taobao store

BGVP S01 Eartips
Bore size: Very wide with narrow opening
Stem length: regular
Feel: firm and sturdy
Bass: 3.25
Midrange: 5
Treble: 5
Soundstage: 3.0
Vocal presence: 3.0
A very interesting eartip with an exceptionally wide nozzle and narrow opening. Treble is vastly emphasize with a hint of bass and midrange. Works very well for dull-sounding earphones but make sure you can fit it 6.5mm diameter bore.
Purchased from BGVP Taobao store

BVGP W01 Eartips
Bore size: wide
Stem length: short and stubby
Feel: short and flexible
Bass: 4.0
Midrange: 4.25
Treble: 3.75
Soundstage: 3.75
Vocal presence: 4.5Short stem and wide bore brings nozzle closer to the eardrums thus enhancement in overall clarity and vocal presence, which means stereo image and presentation are slightly more forward. A slight boost in mid-bass is noticeable. 
Purchased from BGVP Taobao store

BGVP Y01 Eartips
Bore size: Very wide with narrow opening
Stem length: regular
Feel: firm and sturdy
Bass: 3.75
Midrange: 5
Treble: 5
Soundstage: 3.0
Vocal presence: 3.0
A very interesting eartip with an exceptionally wide nozzle and narrow opening. Similar to BGVP S01 but with a smidgen more bass. Works well for dull-sounding earphones but make sure you can fit it 6.5mm diameter bore.
Purchased from BGVP Taobao store

C

Canal Works CW Dual Nozzle (CWU-DECM)
Bore size: wide / short cap
Stem length: short
Feel: soft and pliable
Bass: 3.25
Midrange: 4.5
Treble: 4
Soundstage: 3.5
Vocal presence: 3.75
For neutral tonality with slight bass reduction and laid-back vocal compared to SpinFit CP-145. Otherwise both sound quite similar.
Purchased from Japan through a friend

Canal Works CW Single Nozzle (CWU-ECM)
Bore size: small
Stem length: short
Feel: sturdy and firm
Bass: 4.25
Midrange: 5
Treble: 5
Soundstage: 4
Vocal presence: 4.25
Eerily similar to Radius Deep Mount but with slightly less vocal presence and less transparent. Not suitable for bright earphones.
Purchased from Japan through a friend

Canyon Silikon-Eartips ET400 (Bass)
Bore size: wide
Stem length: short
Feel: soft and firm
Bass: 3.50
Midrange: 3.25
Treble: 4.0
Soundstage: 4.50
Vocal presence: 3.0
Canyon is a German company however these eartips are made in China. Interestingly, I find these eartips very pleasing, especially in staging. The ET400 is laid back yet retains imaging scale and focus very well. Although the packaging says “bass”, the ET400 isn’t bassy or rumbly. I would classify it as balanced with a touch of midrange warmth.
Purchased from Canyon Official Taobao Store.

CleanPiece Anti-bacteria Silicone Eartip
Bore size: narrow
Stem length: short
Feel: soft and flexible
Bass: 4.25
Midrange: 4.0
Treble: 3.0
Soundstage: 3.75
Vocal presence: 3.0
An interesting audiophile’s “sanitary” product from Japan, and made in Japan. How true is the anti-bacteria, anti-microbial and anti-virus properties I don’t know (it comes in a plastic “petri dish”) but I do know these eartips roll-off treble and thicken bass and mid-bass. You lose clarity but gain body and smoothness. Recommended for bright and harsh sounding IEMs.
Purchased from Amazon.jp

E

EarrBond Barreleye Blue 
Bore size: regular
Stem length: regular
Feel: soft with sturdy core
Bass: 3.5
Midrange: 4.25
Treble: 4.5
Soundstage: 4.5
Vocal presence: 4.0
Different from EarrBond New Hybrid series, Barreleye eartips use a sturdy silicone core which give an surprisingly good seal without the squishy feel of foam. Similar to the New Hybrid series, sound is laid back. Barreleye Blue has better clarity, instrument separation, treble extension, stage depth and layering than Barreleye Green and New Hybrid.

However due to its emphasis in the upper-midrange and treble regions, Barreleye Blue isn’t suitable for bright, sibilant or harsh sounding earphones. Group member Vannak Pech described the sound as if “when you apply contrast filter to your image…”.
Purchased from MTMT Audio (Hong Kong)

EarrBond Barreleye Green
Bore size: regular
Stem length: regular
Feel: soft with firm core
Bass: 4.0
Midrange: 4.0
Treble: 4.25
Soundstage: 4
Vocal presence: 4.5
Different from EarrBond New Hybrid series, Barreleye eartips use a firm silicone core which gives an surprisingly good seal without the squishy feel of foam. Similar to the New Hybrid series, sound is laid back. Barreleye Green adds body and bass punch but it lacks the clarity, instrument separation, treble extension, stage depth and layering of Barreleye Blue. 
Purchased from MTMT Audio (Hong Kong)

EarrBond New Hybrid Design
Bore size: regular
Stem length: regular
Feel: soft and spongy
Bass: 3.5
Midrange: 4.25
Treble: 4
Soundstage: 4
Vocal presence: 3.25
EarrBond is softer and more squishy compared to other hybrid eartips, thus more comfortable for long-listening sessions. The moment you put them on, they simply disappear into your ear canals. Furthermore, they isolate well too. Sound-wise these are a bit too laid back for my taste. Also, I could detect some sibilance on a some female vocal tracks. In term of wearing comfort and isolation, this win hands down.
Purchased from MTMT Audio (Hong Kong)

Elecom Spare Ear Cap (EHP-CAP10)
Bore size: wide
Stem length: short
Feel: soft and flexible
Bass: 4
Midrange: 4.5
Treble: 4.5
Soundstage: 4.25
Vocal presence: 4.25
The brand Elecom is relatively unknown outside of Asia. These eartips surprised me with their exceptionally good sound and budget-friendly price. For ￥250 or US$2.50, you’ll get 4 pairs of eartips consist of X-Small, Small, Medium and Large sizes. Sound-wise, it is neutral tonality with emphasis in upper-bass and midrange regions (which adds body) as well as in vocals. I rank these higher than SpinFit CP-145 and on-par with Final Audio Type-E (black) eartips. Everybody should get these eartips if they ever come across it.
Purchased from Amazon.jp

Epro Horn-shaped Tips
Bore size: cone-shaped, tempered (4mm nozzle end, 5mm bell end)
Stem length: regular
Feel: soft and flexible
Bass: 4 25
Midrange: 4.5
Treble: 4
Soundstage: 3.75
Vocal presence: 4.25
Made of graphene and unlike most eartips, Epro has a cone-shaped tempered bore of 4mm at nozzle end to 5mm at the bell. It adds warmth, body and texture to vocals It tames harsh and peaky treble exceptionally well too. It DOESN’T roll-off highs and kills the air and ambient like some other foam tips. What I really enjoy about the Epro is that it adds a buttery smooth to the overall sound which make harsh-sounding earphones, such as the KZ ZS6, listenable again.
Purchased from Treoo Singapore

Epro Truly Wireless Horn-shaped Tips
Bore size: cone-shaped, tempered (4mm nozzle end, 5mm bell end)
Stem length: short
Feel: soft and flexible
Bass: 4.25
Midrange: 4.5
Treble: 4
Soundstage: 3.75
Vocal presence: 4.25
Made of graphene and unlike most eartips, Epro truly wireless horn-shaped eartips have a cone-shaped tempered bore of 4mm at nozzle end to 5mm at the bell. It adds warmth, body and texture to vocals. It tames harsh and peaky treble exceptionally well too. Not suitable for bass-heavy earphones.
Purchased from MTMT Audio, Hong Kong

F

FAudio “Vocal” Premium Silicone Earphone Tips
Bore size: regular
Stem length: regular
Feel: soft and firm
Bass: 3.25
Midrange: 4.75
Treble: 4
Soundstage: 4
Vocal presence: 5
Accentuates on vocal and midrange but it also makes sibilance more noticeable. My favorite vocal eartip is still the SednaEarFit XELASTEC.
Purchased from MTMT Audio, Hong Kong

FAudio “Instrument” Premium Silicone Earphone Tips
Bore size: regular
Stem length: regular
Feel: soft and firm
Bass: 5
Midrange: 4.75
Treble: 3.5
Soundstage: 4
Vocal presence: 4.25
Very punchy, fun, musical-sounding eartips. Sub-bass is exceptional. Vocal and mids are laid-back. Soundstage is average.
Purchased from MTMT Audio, Hong Kong

Fender SureSeal Tips
Bore size: tapered widebore
Stem length: short
Feel: soft, grippy and sticky
Bass: 4.25
Midrange: 4.0
Treble: 3.75
Soundstage: 3.75
Vocal presence: 4.5
Vastly similar to Azla SednaEarFit XELASTEC, Fender SureSeal offers a more laid-back presentation with balanced sound. Mid-bass is a tad fuller. Soundstage slightly wider than XELASTEC but imaging is less precise. SureSeal does not suffer from the upper-midrange ring that plagues XELASTEC especially with DD-based earphones. Expect dust-magnet. All thermoplastic elastomer eartips require regular washing and sanitizing to prevent ears infection.
Purchased from Amazon.jp.

FiiO Silicone (Balanced Ear tips)
Stem length: regular
Feel: soft and flexible
Bass: 3.25
Midrange: 4
Treble: 3.5
Soundstage: 4
Vocal presence: 3.25
Nice sounding eartips with a toned down bass and treble.
Purchased from FiiO store on Taobao (Mainland China)

FiiO Silicone (Bass Eartips)
Bore size: regular
Stem length: regular
Feel: soft and firm
Bass: 4
Midrange: 3.5
Treble: 3.5
Soundstage: 3.5
Vocal presence: 4
This is similar to many stock tips like those from TRN.
Purchased from FiiO store on Taobao (Mainland China)

FiiO Silicone (Vocal Eartips)
Bore size: regular
Stem length: regular
Feel: soft and firm
Bass: 2.5
Midrange: 4.25
Treble: 4.25
Soundstage: 4.25
Vocal presence: 5
These tips cut bass drastically!
Purchased from FiiO store on Taobao (Mainland China)

Filter H270 TPE Eartips
Bore size: regular with grille
Stem length: short
Feel: soft and firm
Bass: 4.0
Midrange: 5.0
Treble: 4.5
Soundstage: 4.0
Vocal presence: 5.0

Is this US$7 per pair Chinese-made TPE eartip comparable to Azla SednaEarFits XELASTEC and Fender SureSeal? I am sorry to say the H270 eartip doesn’t feel and wear like a TPE eartip. Thus, I do suspect it isn’t made of TPE at all. Probably made of silicone at best. Nonetheless, H270 is a very lively-sounding eartip. Bass is quite punchy.

Sub-bass rumble is good. Midrange is crisp and clear. Treble extension is very good. Soundstage and imaging are good. If you can overlook the fact that this isn’t made of TPE like they claimed, this is a pretty decent eartip. In terms of sound, it is closer to SureSeal than XELASTEC. Both eartips have accentuated upper-mids and treble.
Purchased from Filter Taobao official store

Filter H370 Latex Eartips
Bore size: elliptical-shaped, regular with grille
Stem length: short
Feel: soft and firm
Bass: 2.0
Midrange: 3.75
Treble: 3.0
Soundstage: 3.0
Vocal presence: 3.5

This Chinese Filter H370 does remind me a bit of ADV Eartune Fidelity U Elliptical eartip but performs far worse… Yup, in my encyclopedia of eartips this one is pretty bad. First thing you will notice is how boomy and wooly the bass is. It is so bad that it bleeds into the mids. Upper treble is rolled-off, thus lacking a sense of space and openness. All-in-all, the H370 is a dark-sounding eartip with poor technicalities. Comfort-wise is quite good though. What a pity!
Purchased from Filter Taobao official store

Final Audio Type A
Bore size: narrow
Stem length: regular
Feel: soft and firm
Bass: 3.75
Midrange: 5
Treble: 4.0
Soundstage: 4. 8
Vocal presence: 4
Less common than Type E. Let’s call this Type E with a slightly boosted treble and thus lesser bass. As a whole it gives better clarity. The overall tonality remains quite balanced.
Purchased from Amazon.jp.

Final Audio Type B
Bore size: regular
Stem length: regular
Feel: soft and plush
Bass: 4.25
Midrange: 5
Treble: 3.75
Soundstage: 4
Vocal presence: 4
Less common than Type E. Let’s call this Type E with a slightly boosted bass. Overall sound is more round robust as well. My favorite eartips for diffused-field oriented earphones
Purchased from Amazon.jp

Final Audio Type E
Bore size: regular
Stem length: regular
Feel: soft and sturdy
Bass: 4
Midrange: 5
Treble: 3.75
Soundstage: 4
Vocal presence: 4
For balance sound. Tame harsh earphones
Purchased from ConnectIT (Singapore)

Final Audio Type E (Clear, Clear/Red) 2020 Edition)
Bore size: regular
Stem length: regular
Feel: soft and sturdy
Bass: 4
Midrange: 5
Treble: 4.25
Soundstage: 4 25
Vocal presence: 4.5
Sounds cleaner, clearer, brighter and tighter bass than conventional black Final Audio Type E eartip. Improved vocal lucidity. Tonally more accurate as well.
Purchased from Amazon Japan

Final Type E Silicon Eartips for True Wireless (black)
Bore size: regular
Stem length: short
Feel: soft and pliable
Bass: 3.5
Midrange: 5
Treble: 5
Soundstage: 5
Vocal presence: 4
Probably my favorite eartips for true wireless earpieces. These eartips really open-up the sound without adding sibilance or harshness. Bass is tight, controlled, distinct with great texture and clarity. Vocal is neither too forward or backward… Just nice! Currently, my reference to gauge against other TWS eartips.
Purchased from MTMT Audio, Hong Kong

Final Type E Silicon Eartips for True Wireless (clear)
Bore size: regular
Stem length: short
Feel: soft and pliable
Bass: 3.25
Midrange: 5
Treble: 5
Soundstage: 5
Vocal presence: 4
Overall, similar to Final Type E True Wireless (black) but with slightly less bass.
Purchased from MTMT Audio, Hong Kong

J

JVC Spiral Dot (Regular)
Bore size: wide
Stem length: short
Feel: soft and pliable
Bass: 4
Midrange: 4
Treble: 3
Soundstage: 3.5
Vocal presence: 4
For balance sound. Tame harsh earphones
Purchased from Japan through a friend

JVC Spiral Dot SF (Short Flange / Shallow Fit)
Bore size: regular
Stem length: short (shallow fit)
Feel: soft and flexible
Bass: 3.5
Midrange: 5
Treble: 4.5
Soundstage: 4.5
Vocal presence: 4.25
These eartips are meant for true wireless earpieces. These have more bass and vocal presence than SpinFit CP-350 and CP-360. Comparable to Final Type E True Wireless (black) but sound less open and less treble extension.
Purchased from Amazon.jp

JVC Spiral Dot++ (EP-FX10)
Bore size: wide
Stem length: short
Feel: supple and grippy
Bass: 3.5
Midrange: 3.75
Treble: 3
Soundstage: 3.5
Vocal presence: 4
For balance sound. Tames harsh earphones. Cleaner but lesser bass and midrange compared to regular Spiral Dot. Very comfortable for long listening sessions.
Purchased from Amazon Japan

JVC/Victor EP-FX2 (Poor men’s Spiral Dot)
Bore size: wide
Stem length: short
Feel: soft and grippy
Bass: 3.5
Midrange: 4
Treble: 3
Soundstage: 3.5
Vocal presence: 4.25
You get 80% performance of Spiral Dot at 30% of its price. Comfortable for long listening. Good value for money.
Purchased from Amazon Japan

K

KB EAR 10 Silicone Eartips
Bore size: wide
Stem length: short
Feel: soft and flexible
Bass: 3.5
Midrange: 3.75
Treble: 3 5
Soundstage: 3.75
Vocal presence: 4
For balance sound. Tames bass-heavy earphones. Smooth tonality suitable for long listening sessions.Purchased from KB EAR Taobao store

KB EAR A07 Eartips
Bore size: regular
Stem length: regular
Feel: sturdy and firm
Bass: 3.75
Midrange: 5
Treble: 4
Soundstage: 3.5
Vocal presence: 4.25
Suspiciously similar to Acoustune AET07. Heck… It sounds closer to AET07a than AET07. Neutral tonality with emphasis in midrange and top-end sparkle. I find this eartip to have better bass texture, dynamics and vocal presence than SpinFit CP100 and CP145. The A07 is often labeled as “vocal” eartip for most stock tips offering.Purchased from BGVP Taobao storePurchased from KB EAR Taobao store

KB EAR A08 Eartips
Bore size: regular
Stem length: regular
Feel: firm and sturdy
Bass: 4.5
Midrange: 5
Treble: 3.5
Soundstage: 3.5
Vocal presence: 5
Suspiciously similar to Acoustune AET08, this eartip adds thickness to bass and midrange. However, unlike Acoustune AET08, I find it a speck bright. The A08 is often labeled as “bass” eartip for most stock tips offering.
Purchased from KB EAR Taobao store

KB EAR “Columbia” Eartips
Bore size: regular
Stem length: regular
Feel: soft and sturdy
Bass: 4
Midrange: 5
Treble: 3.75
Soundstage: 4
Vocal presence: 4.5
This eartip is worthy of the title “Sony clone”. Sounds virtually identical to Sony EP-EX11M eartip, which my sensitive ears couldn’t tell them apart. For neutral tonality with slight treble roll-off.
Purchased from KB EAR Taobao store

KZ Starline
Bore size: regular
Stem length: regular
Feel: sturdy and firm
Bass: 3.5
Midrange: 3.5
Treble: 4
Soundstage: 3
Vocal presence: 2.75
Purchased from KZ store on Taobao (Mainland China)

These stock KZ eartips come in two versions. The older version was included with KZ ZS3 and KZ ZS5, etc, were no longer available. They are softer and more pliable compare to current ones. Sound-wise, co-blogger Slater prefers the former. They give smoother midrange and cleaner treble. The ones tested here are the current/ new version.

KZ Starline (reverse)
Bore size: wide
Stem length: long
Feel: soft and grippy
Bass: 3.25
Midrange: 3.5
Treble: 5
Soundstage: 4*
Vocal presence: 3
For bright, clear and crisp sound
*soundstage has more depth and height than width
Purchased from KZ store on Taobao (Mainland China)

KZ Whirlwind Silicone Eartips
Bore size: regular
Stem length: regular
Feel: sturdy and firm
Bass: 2.0
Midrange: 4.50
Treble: 4.25
Soundstage: 4.0
Vocal presence: 4.50
Similar to Tennmak Whirlwind, these eartips reduce bass and mid-bass significantly. Projects vocals forward with good presence.
Purchased from KZ Official Store on Taobao

M

Marunana 七福神 silicone eartips
Bore size: narrow
Stem length: regular
Feel: soft and pliable
Bass: 4.25
Midrange: 5
Treble: 4
Soundstage: 4Vocal presence: 4.25
Marunana eartips is recommended by a friend who discovered it from a native Japanese audio enthusiast. These eartips are surprisingly affordable (880¥ for 12 pairs!). Great midrange texture and vocal presence. My only nitpick is they tend to cloud the mid-bass a little but it adds body to lean earphones.
Purchased from Amazon Japan

Moondrop Spring Tips
Bore size: wide
Stem length: short
Feel: soft with pliable stem
Bass: 2.50
Midrange: 5.0
Treble: 3.75
Soundstage: 3.50
Vocal presence: 5.0
These originally come stock with Moondrop KATO. First impression is how suppressed the bass and mid-bass are, which thins the overall note-weight and body. Midrange is textured with good details. Vocal is forward with very good presence.

Treble has good sparkle and crisp, however it lacks that last bit of extension and airiness. Great match for earphones with too much mid-bass or has bleeding mid-bass. The caps are too soft in my opinion. They flap over every time I remove them from my ears, which is very annoying.
Purchased from Moondrop Taobao Official Store

O

Ostry OS100 Tuning Eartips (Blue)
Bore size: regular
Stem length: short
Feel: firm and sturdy
Bass: 3.75
Midrange: 5
Treble: 4
Soundstage: 3.25
Vocal presence: 3.5
Sounds 90% identical to SpinFit CP145 but with a touch more bass and narrower soundstage.
Purchased from Ostry Official Store on Taobao (Mainland China)

Ostry OS200 Tuning Eartips (Red)
Bore size: regular
Stem length: short
Feel: firm and sturdy
Bass: 4
Midrange: 5
Treble: 3.25
Soundstage: 3
Vocal presence: 3.5
Similar to Ostry OS100 but with a tad more bass and less crisp in the treble. Quite a balance-sounding eartip. Narrows soundstage.
Purchased from Ostry Official Store on Taobao (Mainland China)

Ostry OS300 Tuning Eartips (Black)
Bore size: regular
Stem length: short
Feel: firm and sturdy
Bass: 5
Midrange: 4.75
Treble: 2.5
Soundstage: 2.5
Vocal presence: 3.5
The most bass-heavy Ostry tuning eartips of all. Also rolls-off treble the most. It adds tightness and punchiness to the overall sound. However, I find them a bit too forward for my taste.
Purchased from Ostry Official Store on Taobao (Mainland China)

Ortofon silicone eartips
Bore size: regular
Stem length: regular
Feel: very soft and pliable
Bass: 2.5
Midrange: 5
Treble: 5
Soundstage: 4.5
Vocal presence: 4.25
For good midrange, best female vocal, tames bass and brightens treble
Purchased from Ortofon direct (Denmark)

Q

Queen Lab Hybrid Silicone Memory
Bore size: wide
Stem length: short
Feel: sturdy and very firm
Bass: 3.5
Midrange: 5 
Treble: 4.25
Soundstage: 4
Vocal presence: 4 5
Exceptionally good vocal presentations for hybrid. Tighter bass and clearer midrange compared to Symbio W. My favorite hybrid eartip. 
Purchased from MTMT Audio (Hong Kong)

R

Radius Deep Mount
Bore size: small
Stem length: regular
Feel: sturdy and firm
Bass: 4.25
Midrange: 5
Treble: 5
Soundstage: 4
Vocal presence: 4.5
Just like the company’s slogan – Pure Comes True, Deep Mount is the most transparent of all eartips I have tested. Not suitable if your earphone is already bright.
Purchased from Bic Camera (Osaka, Japan)

RHA dual density silicone eartips
Bore size: regular
Stem length: regular
Feel: sturdy and firm
Bass: 3.5
Midrange: 5
Treble: 4.5
Soundstage: 3.75
Vocal presence: 4.5
These eartips enhance details and stereo imaging extremely well. Tighten bass. Projects midrange and treble frequencies more than some eartips. Not recommended for bright earphones.
Purchased from RHA in UK

S

Sennheiser Momentum Eartips
Bore size: regular with “sound beam”
Stem length: very short
Feel: soft and flexible
Bass: 4.5
Midrange: 5
Treble: 4.0
Soundstage: 3. 5
Vocal presence: 3.5
This is the stock eartip from Sennheiser Momentum series of earphones. It has a bold, thick and robust sound signature with buttery-smoooth upper-midrange and treble. Can sound overly warm and muddy when used on dark-sound earphones. Clarity, soundstage, imaging, and details are average.
Purchased from Sennheiser Singapore

Simphonio Diamond Earfit
Bore size: wide
Stem length: regular
Feel: soft and flexible
Bass: 2.50
Midrange: 5.0
Treble: 4.50
Soundstage: 5.0
Vocal presence: 5.0
This eartip has rhombus patterns stamped around the cap (or umbrella) thus the name “diamond” Earfit. This eartip bears some resemblance to Moondrop Spring Tip, however Diamond Earfit is a bit shorter height-wise. Vocal is forward with very good presence. Midrange and treble feels more open and livelier than Spring Tips. Just like Spring Tips, Diamond Earfit thins bass and mid-bass, reduces note-weight. Skip if you prefer bassier eartip.
Purchased from RoadRunner Taobao Store

Softears Liquid Silicone Ear TipsBore size: regular
Stem length: regular
Feel: soft and grippy
Bass: 3.0Midrange: 5.0Treble: 4.50Soundstage: 5.0Vocal presence: 5.0
Very pricey eartips from Softears. Appearance and texture feel just like SednaEarfit XELASTEC, although it says “Liquid Silicone”. Frankly, I have no clue what liquid silicone is other than those used in aesthetics surgery.

However, I find these eartips sound very much cleaner, clearer and airier than both XELASTEC and Crystal. Midrange and vocal presentation are outstanding. Softears Liquid Silicone does not have the upper-midrange “ringing” that plagues the original XELASTEC eartips. Unfortunately, these eartips attracts dirt and dust just like XELASTEC, so clean them regularly if you decide to try.
Purchased from Softears Taobao Official Store

SonicMemory Cup Tips
Bore size: cone-shaped, tempered (4mm nozzle end, 5mm bell end)
Stem length: short
Feel: medium soft and pliable
Bass: 3.5
Midrange: 4.25
Treble: 4.25
Soundstage: 4.0
Vocal presence: 3.75
An alternative to Epro Horn-shaped Tips. It has an overall softer yet balanced tonality. Bass not as impactful and robust. Vocals don’t stand out as much. Nonetheless, I do enjoy the “air” it gives to the sound. Also, these eartips present slightly wider soundstage and more spacious than Epro. Comes with antibacterial properties added, which is a good thing if you don’t have sensitive skin.
Purchased from SonicMemory Taobao Official Store

SonicMemory Fungus Tips
Bore size: regular
Stem length: regular
Feel: soft with a sturdy stem
Bass: 4.0
Midrange: 4.0
Treble: 4.0
Soundstage: 3.50
Vocal presence: 3.50
These eartips look like little pink champignon mushrooms thus the name “fungus” tips. A balanced-sounding eartip with emphasis in bass and low-midrange. Vocals sound slightly nasally and laid-back. Treble lacks air and extension. Soundstage is of average width. If you prefer an open and airy sound with wide-staging, do consider its sibling the SonicMemory Cup Tips. Infused with antibacterial properties.
Purchased from SonicMemory Official Store on Taobao

Sony Clear White
Bore size: regular
Stem length: regular
Feel: pliable and soft
Bass: 4.0
Midrange: 5.0
Treble: 3.5
Soundstage: 4.0
Vocal presence: 4.5
I consider the Clear White an improvement over Sony Triple Comfort. This enhances overall clarity and vocal presence without sounding overly bright or harsh. Top-end sounds more airy. Bass texture improved as well. My only gripe is it isn’t as smooth as I would prefer but this is a small trade off in my opinion.
Purchased from Amazon.jp

Sony EP-NI1000M Noise Isolation Earbud Tips

Bore size: regular
Stem length: regular
Feel: spongy and sturdy
Bass: 5.0
Midrange: 4. 5
Treble: 3.75
Soundstage: 4
Vocal presence: 5.0

This is the most expensive eartips in my collection as of October 2021. These tips retail for US$20 A PAIR! Yes, you hear that right… Two Hamiltons for a pair of eartips!

Deemed to be a replacement for Sony Triple Comfort (EP-TC50), these are eartips with an attitude. They sound like silicone but seal and isolate like a good pair of foam tips. Extremely comfortable and stable fit.

Are they better than XELASTEC? All I can say is both are very different. If you are always a “foam person”, the EP-NI1000 sounds more lively and open than, say, Comply or Dekoni.

Heard from a friend that these eartips don’t last long, so it is better to keep them dry and away from heat. Purchased from Amazon, Japan

Sony Spare Earbuds EP-EX10A / EP-EX11

Bore size: regular
Stem length: regular
Feel: soft and sturdy
Bass: 4
Midrange: 5
Treble: 3.75
Soundstage: 4
Vocal presence: 4.5

Neutral tonality with warm mid-bass and slight treble roll-off. Midrange is smooth and laid-back. Ideal choice for bright and lean sounding earphones.
Purchased from ConnectIT (Singapore)

Sony Triple Comfort
Bore size: regular
Stem length: regular
Feel: spongy and sturdy
Bass: 5
Midrange: 4
Treble: 3.25
Soundstage: 4
Vocal presence: 4.25
For similar to Sony Hybrids but with boosted bass
Purchased from Bic Camera (Osaka, Japan)

Sony Hybrid (discontinued)
Bore size: regular
Stem length: regular
Feel: soft and sturdy
Bass: 4
Midrange: 5
Treble: 3.75
Soundstage: 4
Vocal presence: 4.5
For neutral tonality with treble roll-off
Purchased from ConnectIT (Singapore)

SPEAR Labs nFORM XTR SERIES 500
Bore size: regular
Stem length: regular
Feel: spongy and sturdy
Bass: 4.5
Midrange: 4.5
Treble: 3.25
Soundstage: 3.75
Vocal presence: 4.25
An alternative to Sony Hybrids (EP-TC50M). Compared to the Sony, nFORM has a clearer and tighter bass, with forward midrange. Human voice can sound nasally (a common problem with foam-based eartips). Soundstage is narrow and stereo imaging less distinctive and precise. Nonetheless, nFORM is extremely comfortable for long listening sessions. Suitable for bright and lean sounding earphones.
Purchased from MTMT Audio, Hong Kong

SpinFit CP100
Bore size: regular
Stem length: regular
Feel: soft and flexible
Bass: 3.5
Midrange: 5
Treble: 4
Soundstage: 4
Vocal presence: 3.25
For neutral tonality with emphasis in midrange.
Purchased from Stereo Electronics (Singapore)

SpinFit CP100+
Bore size: regular
Stem length: regular
Feel: soft and flexible
Bass: 3.5
Midrange: 5.0
Treble: 3.75
Soundstage: 4.0
Vocal presence: 3.75
Slight improvement over the original CP-100 especially in the midrange and upper-midrange. However, I feel the top-end is less airy than CP-100. Bass also lacks a bit of punch and dynamics. The “plus” addendum probably comes from the better portrayal of the human voice. True enough, vocals sound slightly more forward and crispier.

Imaging, focusing, instrument and vocal separation definitely improved over its predecessor. Personally, CP-145 is still my most favourite SpinFit.
Purchased from Amazon.sg (Singapore)

SpinFit CP145
Bore size: regular
Stem length: regular
Feel: soft and flexible
Bass: 3.5
Midrange: 5
Treble: 4
Soundstage: 4
Vocal presence: 3.5
For neutral tonality with emphasis in midrange and vocal
Purchased from ConnectIT (Singapore)

SpinFit CP155
Bore size: regular
Stem length: long
Feel: soft and flexible
Bass: 4
Midrange: 5
Treble: 4
Soundstage: 3.5
Vocal presence: 4.25
1 mm longer than CP-100 and CP-145, the additional length and bullet-shaped caps of the CP-155 allow deeper insertion to bring more bass and fuller vocal. 
Purchased from ConnectIT (Singapore)

SpinFit CP220
Bore size: regular
Stem length: regular (double flange)
Feel: sturdy and firm
Bass: 4
Midrange: 5
Treble: 4.5
Soundstage: 4
Vocal presence: 4
For neutral tonality with emphasis in bass, midrange and vocal. For clarity and bigger soundstage, choose CP-240.
Purchased from ConnectIT (Singapore)

SpinFit CP240
Bore size: regular
Stem length: regular (double flange)
Feel: soft and sturdy
Bass: 3.75
Midrange: 5
Treble: 5
Soundstage: 4.5
Vocal presence: 4
Exceptional clarity with good treble extension. Soundstage is one of the biggest I have heard. Vocal presentation is forward. Can get sibilant when matched with bright earphones.
Purchased from Stereo Electronics (Singapore)

SpinFit CP350
Bore size: regular
Stem length: short (shallow fit)
Feel: soft and flexible
Bass: 2.0
Midrange: 5
Treble: 5
Soundstage: 4
Vocal presence: 3.5
These eartips are originally meant for TWS wireless earpieces but a friend of mine suggested they are very good at cutting down bass and midbass. Indeed, these are the “Diffuse Field Target-equivalent” of eartips. They clean up the bass.

Reduces mid-bass bloat or muddiness. Upper-midrange is sparkly and treble extension is one of the best I have heard among universal eartips. Vocal is forward with good clarity. NOTE: SpinFit CP-350 has a very shallow fit. Make sure the earphone nozzle length is at least 5mm in order to fit securely.
Purchased from Stereo Electronics (Singapore)

SpinFit CP360
Bore size: regular
Stem length: short
Feel: soft and flexible
Bass: 3.0
Midrange: 5
Treble: 4.75
Soundstage: 4
Vocal presence’ 5
These eartips are meant for true wireless earpieces. If you find SpinFit CP-350 too short, this one fits between regular CP-145 and CP-350. Bass and low-mids are stronger than CP-350. Vocal is forward with good clarity.
Purchased from ConnectIT (Singapore)

SpinFit CP500
Bore size: regular
Stem length: regular
Feel: soft and flexible
Bass: 4.25
Midrange: 5
Treble: 4
Soundstage: 4
Vocal presence: 4.0
A lesser known SpinFit model. CP-500 gives tighter, punchier bass, better vocal presentation than the popular (and common) CP-100 and CP-145. May add sibilance and harshness to bright-sounding earphonesPurchased from MTMT Audio (Hong Kong)

Symbio W
Bore size: regular
Stem length: short
Feel: sturdy and very firm
Bass: 3.25
Midrange: 4.75
Treble: 3 75
Soundstage: 4
Vocal presence: 3.5
For good midrange, slight treble roll-off
Purchased from Symbio direct (Hungary)

Symbio Orange Peel
Bore size: regular
Stem length: short
Feel: sturdy and very firm
Bass: 4
Midrange: 3
Treble: 4.25
Soundstage: 4.25
Vocal presence: 3.5
Good midrange. Punchier bass, better treble extension and more open-sounding compare to Symbio W.
Purchased from Symbio direct (Hungary)

T

Tanchjim T-APB Air Pressure Balance Silicone Eartips T300T (Treble Enhancing)
Bore size: wide
Stem length: regular
Feel: sturdy and firm
Bass: 4.5
Midrange: 4.5
Treble: 4.5 
Soundstage: 3.75
Vocal presence: 4What’s is T-APB? Simply put it, a hexagonal-shaped internal wall of the nozzle that Tanchjim claims “enhance the comfortness (is there such a word?) by evenly balancing the air pressure inside the ear canal, thus to prevent swelling of the ear canal caused by prolonged use of earphone”

… Marketing aside, the T300T (Treble Enhancing) eartip does pushes some high frequency through but it causes the entire bass spectrum and low-mids to “muddle up”, resulting in a loss of texture and low-end details. Does not go well with “thick-sounding” IEMs but good match for leaner-sounding ones BUT be very careful as it might brighten sound too much. 
Purchased from Hifigo

Tanchjim T-APB Air Pressure Balance Silicone Eartips T300B (Bass Enhancing)
Bore size: regular
Stem length: regular
Feel: sturdy and firm
Bass: 4.0
Midrange: 4.5
Treble: 4
Soundstage: 4
Vocal presence: 3.75What’s is T-APB? Simply put it, a hexagonal-shaped internal wall of the nozzle that Tanchjim claims “enhance the comfortness (is there such a word?) by evenly balancing the air pressure inside the ear canal, thus to prevent swelling of the ear canal caused by prolonged use of earphone”

… Marketing aside, the T300T (Treble Enhancing) eartip is surprisingly neutral despite the “Treble Enhancing” name tag. I find the vocal slightly laid-back and lower-mids a tad muffled. Otherwise, a good choice for IEMs with diffused-field tuning, such as those from Tanchjim and Moondrop.
Purchased from Hifigo

Tennmak Whirlwind
Bore size: regular
Stem length: regular
Feel: sturdy and firm
Bass: 2
Midrange: 4.5
Treble: 4.25
Soundstage: 4
Vocal presence: 4.5
Reduces bass and mid-bass significantly. Let vocal shines through.
Purchased from Tennmak Store on AliExpress

TRN Silicone Eartips
Bore size: regular
Stem length: regular
Feel: flexible with firm stem
Bass: 3.5
Midrange: 3.25
Treble: 3.0
Soundstage: 2.50
Vocal presence: 3.0
Listening to these eartips is like having a thick veil covers the entire frequency spectrum. They simply muffle sound! Bass is clumpy, lacks texture and details. Midrange and upper-registers cover by a layer of haze. Vocal is lackluster and lifeless. Staging is flat and narrow. Imagining is fuzzy. One of the worst eartips I have tested so far.
Purchased from TRN Official Store on AliExpress

W

Whizzer Easytips ET100 (natural)

Bore size: regular
Stem length: regular
Feel: soft and firm
Bass: 3.75
Midrange: 4.0
Treble: 4.0
Soundstage: 4.5
Vocal presence: 3.5

A very interesting eartip that looks like a toilet plunger. The shape may be odd but the sound isn’t. Balanced, clean and clear tonality that is neither too bright nor too bassy. Seals and isolates well too.
Purchased from OperaFactory Taobao Official Store

Whizzer Easytips SS20 (soundstage)

Bore size: wide
Stem length: regular
Feel: soft and pliable
Bass: 3.5
Midrange: 4.25
Treble: 4.25
Soundstage: 5.0
Vocal presence: 3.5

As the title implies, this eartip improves soundstage, and this isn’t a gimmick. It really adds dimension to sound, giving it a more spacious presentation.
Purchased from OperaFactory Taobao Official Store

Whizzer Easytips VC20 (vocal)

Bore size: regular
Stem length: regular
Feel: soft and firm
Bass: 4.0
Midrange: 3.75
Treble: 4.0
Soundstage: 2.5
Vocal presence: 2.5

Not very good. This eartip clouds midrange and boosts low-mid a bit too much for my taste. Resolution is poor as well. Everything just sounds stuffy and dull. Perfect for bright-sounding IEMs though.
Purchased from OperaFactory Taobao Official Store

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RELATED…

The Iconic AZLA SednaEarfit Silicon Tips – Is Their Price Justified? by Jürgen Kraus (2019-12-22)

Announcing The Premium Eartips Project by Jürgen Kraus (2019-10-01)

The Flip Tip: Creating Big Widebore Tips From Reversing Starlines by Slater (2019-09-16)

The post Tweaking Tips – A Simplified Guide To IEM Silicone Eartips UPDATED 2022-05-27 appeared first on Audio Reviews.

We pursue a different approach and have “built” this “Wall of Excellence” brick by brick to list portable audio gear of all types that has been doing a great job for us. And “us” means eight authors. Reconciling such a large number of informed opinions means rigorous and effective filtering. Our selections are therefore relatively safe. We do not compare on our WoE and therefore do not rank. If is’s on it’s on.

This is not a shopping list either and we will not accept requests for additions from third parties. Our wall is strictly personal. Info on all contributors is appended below.

It should be noted that we cannot know every product and therefore our list has holes. But we always strive to keep these as small as possible.

Please bookmark our dynamic Wall of Excellence and keep checking back as it will always be work in progress. You find it easily in the top toolbar.

Now it is time to dip in. Please enjoy yourself.

And don’t forget: If it ain’t here, WE don’t want it :). Check out your eight “bricklayers” below.

Until next time…keep on listening!

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Executive Summary

Not all (premium) dongles are equal – and not all are equally useful for the consumer. A real dilemma. This note discusses the applicability of the different kinds for everybody’s unique needs.

Introduction

There have been hot discussions of dongles (battery-less, source-driven DAC/amps) lately. Two principal endmembers exist, the AudioQuest DragonFly type that minimizes current draw, and the Luxury & Precision W2 type, that draws multiple times the DragonFly’s current, but maximizes power output.

All dongles have their small form factor in common, which is aiming for portable use. Computer applications are not considered in this article (there are additional choices), neither are sound qualities of the individual models, and we focus on the more upscale models.

Technical Aspects

I had already discussed the limitations of low-current-draw dongles in detail in this article.

Co-blogger Alberto Pittaluga writes: price aside, it technically boils down to…little power/current draw = limited output power & quality. 

So pick your poison:

a) If low power/battery preservation is your top priority (i.e.: don’t want to buy a different phone, want minuscule size, etc. —> you have to accept sound and/or pairing compromises)

b) If output power/quality is your top priority (“need” to drive cans, low sensitivity IEMs, planars, etc.) you need phones with bigger batteries.

Both together is *not* (technically) possible, whatever marketing says. And – let’s face it, any device that is limited by its small form factor and without a battery can only be a compromise.

Little current draw/power = limited output power/quality but longer battery life

Which User Type are You?

The participants in the discussion come from three principal groups and therefore from different angles: Android users, iPhone users, and DAP users. All phone users use dongles to improve their device’s sound quality and/or to run iems/headphones not driven by the integrated audio circuits or the basic stock dongles.

iPhone Users

These have the least choice as iPhones throttle current consumption to 100 mA. They are limited to low-current dongles of the DragonFly type. They are also restricted in their pairings but get lots of use between charges.

Android Users

These phones have typically no current-draw limitations and host large batteries as big as 5000 mAh. They can therefore operate the W2-type dongles, too. And whereas these W2-types are the most powerful dongles, they still do not drive power-hungry headphones perfectly well, according to Headphonesty. The price to pay is much higher battery consumption.

DAP Users (downgrading to phone)

Whereas dongles are upgrades for all phone users, they are damage limitation for the sonically indulged DAP crowd. Some people sold their DAPs to go with the powerful W2-type dongle which comes sonically closest to their DAP.

Concluding Remarks

Since no dongle does everything we want, it comes down to need of what it should do for us, depending on our perspective. And all the points of the different user groups are valid. But what works for the goose may not work for the gander in this case, for technical reasons.

The consumer has choices: some want small and powerful, some small and low current, others don’t mind strapping an internally powered monster to their phone, and the rest wants DAPs. Before buying, we may want to define our requirements in order to get full enjoyment out of our new device.

Until next time…keep on listening!

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Disclaimer

This article is a summary of discussions with co-bloggers Kazi Muhbab Mutakabbir, Alberto Pittaluga, and members of our marvellous Facebook Group https://www.facebook.com/groups/audioreviews.

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You find an INDEX of our most relevant technical articles HERE.

The post The #1Dongle Dilemma – Power Vs. Compatiblity appeared first on Audio Reviews.

What Is…

“Dongle” is the casual term for a tiny portable USB DAC/amp that is sourced by its host device (phone/tablet, dap, computer). It is derived from software keys of this kind of shape.

Early Steps

The idea of a small, portable DAC/amp in the shape of a USB “thumb drive” goes back to a conversation between some industry reps and consulting audio engineer Gordon Rankin at the Rocky Mountain Audio Fest 2010. Gordon had been designing DACs since the early 2000s and had lots of experience with asynchronous code, needed to minimize timing errors (“jitter”) that compromise an USB-audio signal. You find details of the dongle inception in my AudioQuest Dragonfly Red review.

The device was designed for larger headphones and with iPhone portability in mind – but iPhone limits the current draw to 100 mA to protect battery life. One of the challenges was therefore to minimize current draw, which, unfortunately, limits performance as we will see below.

In 2015, Apogee released their famous “Groove“, a very powerful and large device that draws 340 mA, and it has an output impedance of 20 Ω. This is not a dongle sensu stricto as it only works with computers and mainly with high-impedance headphones (with some exceptions).

It took until 2016 until the first USB devices had a current draw small enough to work with iPhone: AudioQuest’s DragonFly Black v.1.5 and DragonFly Red. Timing was right as Apple removed the headphone jack in the same year, as of iPhone 7. And most Android phones followed suit.

Apple offers a decent low-priced dongle of their own that is good value but is limited in power. My review of the “Apple Audio Adapter” is one of the evergreens of our blog.

The DragonFlys have an output impedance of <1 Ω, which makes them work well with headphones and iems alike. They do not have any physical controls and are operated through their host devices.

DragonFlys Black and Red still lead the pack in terms of low-current drain (if exempting the Apple Audio Adapter). You find drain comparisons between some models here.

Most dongles need a Windows driver, but all of them are plug’n’play with phones , tablets, and Apple computers.

From Thumb Drive to Dongle

The very first external iPhone DAC/amp, the Apple Audio Adapter, was physically a true dongle, and a seamless headphone/earphone cable extension.

The first non-Apple devices (the AudioQuest DragonFlys) had/have a USB-A plug and resemble a thumb drive. The USB-A pug works seamlessly with the Apple camera adapter and any computer. Android phones had no preference with developers as they had no standardized socket at the time and still do not produce music bit perfect (they resample a 44.1 kHz signal to 48 kHz).

Most of the Android devices had micro-USB ports until the USB-C port (finalized in 2014) was slowly spreading starting in 2015. Today, there are more than 100 dongles on the market, most of them featuring a USB-C port. And so do the latest Macs.

DAC/amp and music/power source are connected by a short USB-C to USB-C cable, most of them coming with an additional USB-A adapter. None of these has a USB-C plug, probably for the purpose of stability (the USB-C plug could break off easily). But the need for this additional cable turned the original thumb-drive into a true “dongle”.

Some devices have a fixed USB-C cable, and iPhone users are horrified by the snakes they produce when connected to the Apple camera adapter. Third-party USB-C to lightning cables may come in handy, but their MFI chip draws “healthy” additional current.

Technology – What makes a Dongle’s Sound?

There are many variables that contribute to the sound, such as the dac implementation which includes software coding and filtering, the analog output stage, and the amp design and implementation.

Therefore, same dac chip does not mean same sound in different devices. In my case, The Khadas Tone2 Pro, EarMen TR-amp, Hizids S9 Pro, Shanling UA2, and DragonFly Cobalt feature the ESS ES9038Q2M dac chip – and they do not sound even remotely close.

So it does not surprise that some high-end dacs and some budget dongles have the same dac chip, which are a relatively cheap ingredient. Some high-end manufacturers therefore do not disclose the dac-chip used in their specifications.

Characteristic Chip Sound?

Since buyers cannot audition dongles in most cases, many buying decisions are based on chip brand and model. Descriptions of characteristic sonic signatures based on chips by certain manufacturers echo through the blogosphere. Co-audioreviewer KopiOkaya summarizes them for us:

1. ESS Sabre (US/China) – neutral to neutral-cool, analytical, detailed, fast punchy bass, great dynamics, impressive soundstage and separation. Modern sound. “ESS glare”.

2. AKM (Japan) – neutral to neutral-warm, vocal-centric, laid-back/mellow, bodied. Can sound forward on some models. Some dislike the “AKM Velvet Sound” claiming that it sounds flat and lifeless. Modern sound with a classic twist.

3. Burr Brown/Texas Instruments (US): Natural tone with very good music texture. Generally sound neutral to neutral-warm. Their earlier multibit models (for example: PCM1704UK, PCM63P, etc.) sound extremely musical and dynamic at the same time. Can sound forward with average soundstage on some models. Traditional analog “solid-state” sound.

4. Cirrus-Logic/Wolfson (US/India/UK) – A staple of Apple products since their first generation iPod. Natural tone with warmth and body. Vocal-centric with good dynamics and music texture. Earlier Wolfson DACs can sound wooly and lacks resolution. Traditional analog “tube” sound.

As KopiOkaya points out to me, this does not consider the jitter-reduction and error-correction clock, LPF/IV stages, and power supply.

DragonFly creator (and therefore “dongle inventor”) Gordon Rankin told me that these four points are “totally off“, and “you could not classify these brands that way. There is too many factors to pigeon hole a sound for any DAC: power, filters, analog design, digital design, software etc.”. And that’s what I experienced with my devices featuring the ESS ES9038Q2M dac chip.

According to Gordon, “the difference [for example] between DragonFly Red and Cobalt is more than the dac chip. Power, filtering and new controller make up a big part of the difference in sound. More so than the dac chip itself“.

So, maybe the four points above apply to poorly implement dac chips?

Technical Limitations and Realistic Expectations

The dongle DAC/amps are limited by their (portable) source – and by Ohm’s law. Transducers are moved by current. Such devices that are optimized for low current drain/little battery consumption do not work well with low impedance/low sensitivity iems/headphones, as such require a lot of current.

Dongles optimized for low-current draw lack certain features: for example high-speed USB and balanced circuits that would add to the current draw.

If the required current cannot be provided, the iems/headphones start distorting, which first becomes evident at the low end as it needs the most current. The right pairing is therefore important and I am surprised that some experienced testers ignore this.

It’s the current, stupid (and not the power)!

Such dongles that draw lots of current from the host device may provide more amplification power and less distortion (and balanced outputs etc.), but they will drain your phone’s battery in no time – or don’t work with some phones at all.

Examples of popular powerful dongles are the Shanling UA2 and Hidizs S9 Pro, that consume twice as much battery as the DragonFly Red – which defies the idea of portability. You find a power drain comparison between selected models here.

The real current hogs are limited to operation with a computer, but what is the point of a small form factor for stationary use?

Not every small device is portable!

Decoding Acrobatics

Most dongles decode MQA, which is apparently a useless format. And even the cheaper models manage sample rates up to PCM 32-bit 384 kHz and DSD128 (DoP), as offered by some streaming services.

This may be interesting for $$$$ desktop DAC/amps, but why does anybody need such sample rates in a $50-100 device with limited sound quality to begin with – while forking out that monthly subscription fee? Sounds like a “gimmick” to me.

Most renowned reviewers such as Steve Guttenberg are perfectly happy with CD quality, even on their $$$$ devices. Works for me, too.

Rigour in Dongle Evaluations

Dongles underlie the same standard evaluation criteria as self-powered DAC/amps when it comes to sound quality, but there are some special considerations adherent to their lack of battery. As they were designed to drive headphones from smartphones on the go, portability is the main criterium. And portability is defined by size/weight and synergy with the host device. Not every small device is portable.

There are compromises between:

• small size and performance
• source’s battery consumption and dongle performance

The small form factor limits the size of the logic board and therefore the space for electrical components – which requires shortcuts that take away from performance (but add to the price).

The other compromise comes from the aforementioned current limitation that restricts technical features, amplification power, and headphone pairing.

Such devices that are not designed with energy conservation (and hence portability) in mind do not work well or not at all with phones. They are not (very) portable and essentially restricted to computers.

In this case, their small form factor is pointless and even disadvantageous, as these dongles have to stand comparison with self-powered, larger DAC/amps that offer better performance at similar prices – and therefore better value.

Since dongles have limited power, much of their value lies in the sound quality.

In summary, when evaluating dongles, the analyst must have a good understanding of what these devices are supposed to do and how they achieve it.

Consumer Choices

As elaborated on above, the user has choices: either low-battery drain or high power and additional features – but not both. Many popular powerful dongles with lots of features are rather useless with a phone, and many low-current dongles are problematic with current-hungry transducers.

The choice is yours, but my dongles have to be as portable as possible.

Concluding Remarks

OK, “1001 Facts” may be an exaggeration, but now you probably have a better idea what dongles are about. I personally use a phone with dongle as I do not want to carry a dap, and because the small DAC/amp can be swapped between my current and future devices.

Over time, my dongles may have a higher life expectancy than my phone and also battery-operated DAC-amps such as the hip-dac or ifi Nano BL.

Until next time…keep on listening!

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Disclaimer

My knowledge of these devices benefitted greatly from discussions with the USB-audio pioneer Gordon Rankin of Wavelength Audio Ltd., co-bloggers Alberto Pittaluga & KopiOkaya & Kazi Mahbub Mutakabbir & Biodegraded, and Chiqui Vásquez from hiendportable.com. AudioQuest’s Stephen Mejias provided the historical details. I thank them all.

Our generic standard disclaimer.

You find an INDEX of our most relevant technical articles HERE.

The post 1001 Critical Facts About Dongles (Source-Powered Portable DAC/Amps) appeared first on Audio Reviews.

Nozzle mesh screens sometimes look like a decorative piece or something just to keep the ear juice out. They can create problems though when they wick up too much moisture or modders decide to remove them completely. Below you can see up close images of various nozzle mesh screens serving a vital function – to dampen unwanted resonances. The screen openings themselves (number of holes + diameter of holes) can also factor into the tuning of the earphone, but this was not included as part of this investigation. Below are samples of certain earphones where nozzle screens were discussed in more than passing on certain forums, as well as a popular modder tool otherwise known by the name of micropore tape or paper tape.

KZ ZS3

It was quite the rage to remove these screens and I see why. Mine was actually two plastic screens stuck together. Was this a mistake or on purpose?

SONY MH755

Reviewed here. Modders like to remove the foam plug, but do not remove the black mesh screen. It tames the peaks at 2.8kHz and 5.3khz giving it almost a textbook Harman curve. Very much important noted by certain modders like Slater.

BQEYZ SPRING 1

Our takes on the Spring 1 here. Modders claimed by removing the screen it would get rid of the woolly bass. I removed mine and the quality of the bass did not change, but treble peaks were turned up giving the illusion of improved bass. The bass was just masked by the extra treble punch. Again, I do not recommend removing unless there wasn’t enough upper midrange in the stock tuning. I have heard that other BQEYZ models employ tuning filters directly on the BA units, so this might explain why the screen only has a minor impact.

MOONDROP KANAS PRO

We covered the KPE exhaustively here. Notorious for clogging with moisture in high humidity areas or sweaty ears, Moondrop eventually started selling replacement nozzle screens and included them in subsequent models like the Starfield. They have an interesting arrangement of a small rectangular area with extra damping coverage. Similar to using a partial piece of micropore tape. Again removing it introduces peakiness. Not recommended.

MICROPORE TAPE (3M NEXCARE PAPER TAPE)

Micropore tape has a very irregular pattern. Not much to say about it other than it doesn’t seem to target any specific frequency. All the other filters are uniform and tend to dampen certain frequencies. Useful as a butter knife, not a scalpel.

SUMMARY

So personally, I do not recommend removing nozzle mesh screens unless planning to replace or mod with something else. There might be exceptions such as pure balanced armature IEM’s that utilize resistance damper filter plugs on the end of the balanced armature itself. Therefore the nozzle screen is not like putting a screen door on a submarine, most appear to be used as resistive dampers to tame the frequency response. I’m not suggesting it is wrong to remove the filters, but be aware of the consequences. If there are other earphone modding materials you would like to see up close and personal, leave a comment below or feel free to get in touch with us and we will see what we can do to expand this article.

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DISCLAIMER

Sometimes I stare blankly at walls.

Our generic standard disclaimer.

About my measurements.

You find an INDEX of our most relevant technical articles HERE.

The post Nozzle Screen Filter Impact on Frequency Response appeared first on Audio Reviews.

A note on Beryllium drivers in earphones.

The upcoming US Presidential Election, the ongoing COVID-19 pandemic and the frequent AliExpress packages delay aside, 2020 is a great year for the audiophile community. The technology of beryllium diaphragm is currently in its matured state. Several headphone manufacturers have re-ignited the interest in the material by bringing more affordable beryllium driver-based products to the masses. Beryllium is renowned for its low density, high tensile strength and high flexural rigidity – an ideal material for transducers. This article will explore beryllium as a high performance material in audio applications.

Beryllium is a material with the symbol Be and its atomic number is 4 on the Periodic Table of the Elements, atomic weight 9.012182, is the lightest alkaline earth metal. As a free element, it is a steel-grey, strong, lightweight metal; lighter than commonly used aluminum and titanium, and its strength is 4 times that of steel. An indispensable and precious material with applications ranging from x-ray tubes to scientific instruments and precision components. It is also widely-used extensively in aerospace, telecommunications and metallurgical industries.

Beryllium has a reputation for being brittle. At room temperature, beryllium is inherently a “hard” metal with closely-packed hexagonal crystal structure. However, the level of brittleness is process related. There are two processes that are currently used to manufacture beryllium transducers – Physical Vapor Deposition (PVD) and Powder Metallurgy (Powdered Metal).

Beryllium has exceptional stiffness of a Young’s modulus 287 GPA. The modulus of elasticity of beryllium is approximately 50% greater than that of steel. The combination of its stiffness and a relatively low density results in an unusually fast sound conduction speed in beryllium at about 12.6km/s under ambient conditions.

The advantages  of beryllium as a diaphragm material have long been acknowledged. Its exceptionally high stiffness-to-mass ratio is far beyond that of polymer or carbon-based materials, allowing beryllium to deliver even tighter, faster and cleaner bass response. A midrange that is natural-sounding, fuller with exceptional details and texture. With the rigidity and elasticity of beryllium, the treble can be extend even further without harshness or grain, resulting in a transparent, crisp sound that is comfortable for long listening sessions.

A diaphragm, for example, should move in a perfect pistonic motion (like a piston), with all points moving in uniform and only in the desired direction. Breakup occurs when the forces acting upon the diaphragm overpower its structural integrity and different points on the surface begin moving in different times relative to one another. Because beryllium is extremely light and stiff, it does a better job of maintaining its structural integrity under load, avoiding breakups when compared to conventional diaphragm materials. Beryllium stays pistonic throughout the same frequency range which tracks signal more accurately when an equalisation is applied. Thus making it more responsive to tone adjustments.

Even more critical, however, is the efficiency at which sound travels through beryllium. This is important because the frequency at which the first breakup occurs in any metal, is analogous to the speed of sound through that metal. The speed of sound through beryllium is nearly 2.5 times faster than that of aluminum or titanium. This means the first breakup will occur at a much higher frequency – well outside the audible range in most cases. What is more, when breakup does occur, beryllium’s greater stiffness ultimately reduces the amplitude of those breakups, resulting in very low harmonic distortion.

High frequency breakups cause rough and “peaky” frequency response that typically resulting in a long decay in the time domain (also referred to as ringing). This effect is particularly evident in the top octave response and decay differences between the smooth, fast-decaying beryllium driver and the peaky, long-ringing ribbed titanium driver.

Over the years, companies such as Focal, Periodic Audio, Dunu, Campfire Audio, Final Audio and Master & Dynamic, etc, have offered beryllium-based headphones. Despite its many benefits, beryllium has never been adopted as widely as polymer or carbon-based drivers, and has mostly been relegated to esoteric head-fi components. This is due largely to expense and complexity, since beryllium is rarer and traditionally more difficult to isolate and refine. But modern day refining and manufacturing techniques are reducing the cost of beryllium, while at the same time further enhancing its performance and reliability.

With recent launches such as Dunu Luna and Final Audio A8000, as well as the-soon-to-release KBEAR BElieve, audiophiles will have more choices for affordable beryllium-based earphones. Indeed, 2020 is a year to rejoice! 

References

Article & Graphics:

Adams, Michael., & Berger, Ken. (2012). Growing The Loudspeaker Ecosystem: A discussion of the use of beryllium in transducers. Live Sound International, 56-60. www.ProSoundWeb.com

Other sources:

D.W., Jr., and Burke, J.E. (Editors) (1955), The Metal Beryllium, The American Society of Metals.

Hausner, H.H. (Editor) (1965), Beryllium – Its Metallurgy and Properties, University of California Press.

Schetky, L. M. and Johnson, H.A. (Editors) (1966), Beryllium Technology, Vol. I and II, Gordon and Beach Science Publishers, Inc.

Hausner, H.H. (Editor) (1967), The Beryllium Metals Handbook, General Astrometals Corporation (1967).

The post Believing in Beryllium – A Sound Belief appeared first on Audio Reviews.

This subject came to me one day when I was replying Sunil’s comment on “Tuning The KBEAR Diamond – A Killer Earphone Ready To Go!” on Audioreviews.org. What set me thinking was the fact that many audiophiles are still vastly unfamiliar with Chi-Fi (China Hifi) tuning. Why are Chi-Fi earphones tuned in a certain way? Is there anything a tuner could do to tweak the sound to suit the western ears more? Without going too technical, I will try my best to explain the rationale behind them.

First of all, we must understand the cultural differences. You see, the term “audiophile” or fever enthusiast (“发烧友” in Chinese) did not exist until the end of last millennium. Before that, most Mainlanders were still very poor. Many were labourers, factory workers, miners and farmers, etc. High-fidelity audio enjoyment was the last thing in their minds. Trying to make ends meet in their livelihoods was top priority. Even if the Mainlanders have access to a decent piece of audio equipment, it would cost them an arm and leg, or worst – got thrown into jail. You see, the equipment acquired were probably smuggled from Hong Kong, costing 4 to 5 times its original retail price in the former British colony. Only the very wealthy land-owners, factory-owners, traders, merchants and high government officials could afford such luxury and avoid prosecution.

So, what has this got to do with Chi-Fi tuning? Plenty! You see, most Mainlanders who grew up in that era had never experienced or heard a decent-sounding piece of audio equipment. Foreign Hi-Fi gears were extremely rare. Their domestic “HiFi” products were still largely based on circuitry cloned from well-known foreign brands (such as vintage Western Electric, RCA, Telefunken, Marantz, etc), using inferior components that were poorly implemented and heavily compromised (off-specs).

Loudspeakers from those days were based on front-loaded horn designs, using horn transducers dated back to the 50s and 70s (yes, many of those horn speakers were previously used in public address systems or emergency warning systems). Folks who have experienced or have used horn speakers in the past can relate their blaring sound to Chi-Fi tuning (both eerily similar).

Besides equipment, one of the most obvious reason is recorded music. Mainland China then did not have access to music from other Chinese-speaking territories such as Hong Kong or Taiwan. In fact, many songs were banned because the lyrics were deemed inappropriate to the communist doctrine and ideology. If you have ever heard Mainland Chinese recordings dated back 30-40 years ago, they were shouty, harsh and ear-piercing (plenty examples on YouTube). Why such tonality? The idea is high-pitched sound brings attention and awareness effectively. Imagine the loud shriek from your wife, girlfriend, sister or mother, etc, trying to capture your attention.

Today, the age demographics of many Chi-Fi bosses are in their late 20s, early 30s. Owners of KZ and Yinyoo are in their early 30s. Owner of TRN in his late 20s. That means these folks had their childhood in the 1980s and 1990s, which matches our earlier observations perfectly. They grew up listening to equipment that was less than optimum, with sound that resembles those playing from front-loaded horn loudspeakers. Many of them cannot relate to warm and mellow tones. In fact, they consider such tonality muddy and lacks clarity.

As a tuner for Chi-Fi earphone manufacturers, I often encounter difficulties and frustrations trying to convince their management and engineers to accept a certain tone or sound characteristics. They are judging my tuning based on their own experiences of how “good sound” should be represented. They cannot understand why “blurry and unclear” (in their own vocabulary – “模糊不清”) sound would appeal to the westerners. For earphones that are both sold domestically and exported, I have to tune for both the Mainland and western consumers. Therefore it isn’t easy striking a balance between the two audiences.

Do take note that Chi-Fi earphone manufacturers will ALWAYS place top priority on domestic and territories sales (which includes Hong Kong and Taiwan). Next comes Japan, Korea, Russia and Southeast Asia. North America and Europe are at the bottom of their priority list. Ironically, both western markets have the most influence on the buying decisions of many earphone enthusiasts around the world. Trying to convince Chi-Fi manufacturers to accept tuning that suits the western ears is never an easy task. Often times they will partially tweak or simply proceed with their own tuning preferences without acknowledging the tuner.

Can tuners do anything to change or improve the situation? Frankly no… Their management and engineers have the ultimate say to how their earphones should sound. Do tuners care? Yes, of course we care. Imagine tuners as teachers. When students don’t do well in their exams, it upsets the teachers. Same sentiment…

Back to Sunil’s comment. He wrote – “It is only the good ear that is able to catch good audio quality and it does not depend on whether it is western or eastern…” – I have to disagree. I am sure these Chi-Fi manufacturers have exceptional “ears”, but whether their “ears” could agree with western interpretation of “good sound” is another chapter. What constitute as “good sound” is subjected to cultural background, individual upbringing and personal experience. As tuners, we can only try our best bring out the best from the available drivers to make them sound as appealing to every human ears as possible, regardless of race, culture or locality.

On a positive note, I have personally witnessed tremendous improvement in the tuning of many Chi-Fi products (not just earphones) in the past 2-3 years. This is due to an increased wealth among middle-class Mainlanders, thus more of them are exposed to top-tier, high-quality foreign brand audio products. Slowly but gradually, they have got the opportunity to experience audio gears from around the world. This makes it a bit easier for tuners to convince Chi-Fi manufacturers to accept western tuning. As a result, more Chi-Fi products suitable for western ears are released (such as BLON, Tanchjim, Moondrop, Fearless and Tansio Mirai, etc). This is an ongoing trend I have observed. Expect more exciting Chi-Fi products in 2020 and beyond! 

Further Reading

Our Year 2019 In Review

Our Favourite Earphones of 2019

Tuning The KBEAR Diamond

The Principles Of Reversible Modding

The post Chi-Fi Tuning – Why It Sounds So Damn Piercing To Western Ears? appeared first on Audio Reviews.

KopiOkaya (more) and I (less) recently started helping manufacturers Blon and KBEAR with tuning earphones (we reported) – for free. This came from cumulative frustration with purchases and review units of models that did not appeal to the western ear (including KopiOkaya’s). The idea was to help with generating a product that is universally liked and that works right out of the box, at an attractive price.

Our first project was the KBEAR Diamond (name suggested by co-blogger and Head-Fier Slater). It sports a “Diamond-Like Carbon” (DLC) coated dynamic driver, one that reacts very sensibly to the smallest changes. Not an easy task keeping balance across the frequency spectrum. Therefore, much of the tuning was done by applying different filters. One thing we recognized right away was the potential of this earphone.

What the heck is a DLC coated driver?

KopiOkaya and I received two Betas, we listened, measured, and communicated via Facebook Messenger, often both testing simultaneously. This was not always easy, considering the 15 hour time difference between Singapore and Calgary.

You may wonder why we did not choose a FR that plots between red and blue. I would have preferred this but the tuning filters did not allow it.

The first iteration (green) was too bassy, the second (red) was not bassy enough (that is: good for jazz, classical, but not “fun” enough for most other genres). In no case was the cable particularly attractive. We also had to pick our own eartips and recommend them to the manufacturer. We wanted to make sure this iem works right away and that no upgrades are required.

One of the last steps was deciding on the cable entirely based on sound!!! I am not a believer in cable sound differences (you know they cannot be measured) but HOW WRONG I WAS. We had two cables available, the pink OCC (Ohno Continuous Cast) cable in the title photo above and the grey OFC (oxygen-free copper) cable (see below).

What the heck is Ohno Continuous Cast?

The KBEAR Diamond’s sound with the pink OCC cable was disappointing to both of us: way too bassy, which congested the low end. Also too punchy. No, that can’t have been it. KopiOkaya and I were equally horrified…such a poor result after all this work?

Plugging in the grey 8-core OFC cable created a totally different and much more balanced, more appealing sound. Smoother and more homogeneous throughout the frequency spectrum with a way more articulate bass. Done! Bingo! And it is obvious that, if the sound with one cable is perceived as awful but attractive with another, that there MUST be a difference. The KBEAR Diamond is obviously sensitive to such cable differences and is therefore a good object for testing your cables with. The culprit cannot be the impedance profile, which is usually flat in a single DD so that cables with different impedances would still result in the same frequency response. Beats me why these differences.

We also decided on a quality leather case to complete the package, and not a soft baggie or a pleather case. This earphone is worth it. In the end, we are very happy with the result: a well-built, great sounding earphone with good accessories at an attractive price. Let’s see how it will be received by both consumers and reviewers. Not sure whether I will write a full review of the final product or just a detailed characterization. We also hope our contribution will inspire other manufacturers to follow suit and put more emphasis on the small details that usually make the big difference.

The KBEAR Diamond has been available since 15 December 2019, initially limited to 500 pairs, at ca. $79. KopiOkaya and I will not receive any compensation for our work. After all it is our hobby. And on to the next project…

Keep on listening!

The post Tuning The KBEAR Diamond – A Killer Earphone Ready To Go! appeared first on Audio Reviews.

Reading time: approx 10 minutes] 

With recent introduction of Diamond-Like Carbon (DLC) and Carbon Nanotube (CNT) coatings to earphones and in-ear monitors, such as Campfire Audio Solaris, Moondrop KXXS, Tanchjim Oxygen, iBasso IT01S and BLON BL-03, etc, we are witnessing an on-going “carbon war” to capture consumers’ attention. So, what is carbon-coated transducer? Let me walk you through this art and science.

Today, many earphones manufacturers promote their products equipped with carbon-coated transducers, some claiming the use of proprietary “black magic” drivers as a core selling point. So what is the impact of carbon-coated drivers on the sound?

First of all… what is a transducer? 

If you can remember your high school physics lessons, you probably vaguely recall how a moving-coil loudspeaker works. An earphone driver shares the same working principles as a loudspeaker. The structure may be different but operation-wise, both are identical. Both need to input an analog signal. Electrical signal passes through a magnet to drive a coil, which in turn vibrate the diaphragm to produce sound. 

What is a good diaphragm?

Before we look at materials, let’s understand how a diaphragm directly affects the sound. An ideal earphone diaphragm should have relatively low mass and good rigidity. In addition, it must have good damping properties to absorb the unnecessary flutter generated by the diaphragm during vibration.

Unfortunately, low mass and rigid do not always occur simultaneously. Earphones manufacturers and designers have to take into account these two requirements as much as possible. Manufacturers will start with two ideas: the mechanical design of the diaphragm and material properties of the diaphragm.

Many diaphragms are reinforced with “ribs” around the circumference to increase its rigidity. Different rib design and shape of the dome affect sound. Development of high-performance transducers require a lot of testing, mathematical models, assembly pairing, etc, which inevitably increases the cost of the driver.

The current development in moving coil transducer technology has entered a bottleneck that forces manufacturers to experiment with various materials. Different material gives different performances and sound signatures. Materials range from plant-base pulps, animal skins, polymers, alloys to composites. For example, earlier versions of Apple EarPods adopted wool-infused paper cone and polymer composite diaphragm. Generally, paper diaphragm offers low cost options and gives reasonable midrange to low frequency responses. However its disadvantages in rigidity and weight, which limits its performance, also means that paper is rarely used in higher tier earphone models. Today, the most common diaphragm material is polyethylene terephthalate (PET), a kind of polymer film.

With the advancement in material sciences and production methodology, medium and high-end earphones often use composite diaphragms. Such diaphragms usually consist of at least with two materials. For example, PET for low frequency rumble and titanium for high frequency transient and detail. In some cases, the diaphragm is made entirely of alloy. Such is known as “metal diaphragm”. Examples are titanium and beryllium, which have excellent weight to strength ratio but are costly. Besides titanium and beryllium, carbon materials such as graphene, CNT and DLC has gradually emerged. Such materials have a much higher stiffness than metal. For example, DLC has a Young’s modulus 1050 GPa compared to 287 GPa for beryllium.

Come, Meet the “Carbon Family”… Due to the “deformable” nature of carbon atoms, different substances will be formed under different atomic structures, such as graphene, CNT and DLC – all of which are allotropes of carbon (structurally different forms of the same element). 

Invented in the early 1970s, Diamond-Like Carbon, or DLC, is a hydrogen-containing amorphous carbon material. Its atomic structure is between H (hydrogen atom) and SP3 (diamond). As the name suggests, its properties are similar to natural diamonds, which includes extreme hardness, high corrosion and wear resistant, and very low friction.

The ultra-low mass of DLC-coated diaphragm achieves a perfect balance between acoustic velocity and internal resistance. Its high sensitivity gives excellent transient response for precise sound reproduction. Transducers using DLC-coated diaphragm are characterised by distinctively clear tonality that is crisp and transparent, especially in the midrange and treble regions. Details clearly defined. Bass transients and attacks are fast and precise. Distortion is vastly minimised.

Compared to other member of the “Carbon Family”, DLC is more difficult to process. The traditional approach requires a high temperature, high pressure environment, which resulted in very high energy consumption. Fortunately, the production of DLC has gone “green” in recent years. Companies such as DB Digital Technology Co., Ltd in Dongguan (parent company of BLON) uses low-energy production methods and much simplified manufacturing procedures, production capacity of DLC has improved by 3~4 times. More importantly, the reliability of DLC-coated diaphragm has improved as well. In addition to their BLON line of earphones, DB Digital Technology has been supplying DLC-coated transducers to several domestic and international earphone manufacturers under various brand names.

With decreasing production costs and increasing quality, DLC has become the ideal coating material for earphones manufacturers in the last decade. This “wonder” material has even captured the attention of Grammy award-winning recording engineer/music producer Luca Bignardi, who set the tone for some of the earlier DLC-coated earphones. Therefore good material still has to couple with good tuning to produce exceptional sound in earphones.

In the past two months, Jürgen and I have been working closely with KBEAR and BLON to co-tune two highly-anticipated earphone models – one uses DLC-coated driver, another based on CNT-coated driver. Both earphones are tuned to suit “western ears”. So far, we are progressing well with early-betas sounded extremely promising. We hope to bring music artistry to the next level, offering fellow audiophiles the best possible audio experience and enjoyment by adopting this truly advanced driver technology – thus fulfilling the perfect marriage of art and science.  

You find an INDEX of our most relevant technical articles HERE.

The post Lucy In The Sky With Diamonds – The Euphoric Effects Of Carbon-Based Drivers appeared first on Audio Reviews.

Purpose: this cookbook aims to clarify and streamline the information in REW’s original help file in order to save time and frustration with the setup…and the measuring process.

This is work in progress, don’t expect it to be perfect right away. If there is something wrong, please point it out to us. We are also happy to help: if something has not been explained properly and you are hanging, feel free to send Jürgen an email asking for clarification.

The original REW help index (read as often as possible): https://www.roomeqwizard.com/help/help_en-GB/html/

What you need: 

1. A computer with external speaker(s).
2. The REW software (free download: https://www.roomeqwizard.com).
3. A USB microphone OR a calibrated measurement microphone (like this Dayton imm-6).
4. If you don’t have a USB microphone but the second kind (“Dayton”), you need an USB audio adapter such as this one between the mic and the computer’s usb. Port. It is technically an ADC (Analog Digital Converter).
5. A TRS to TRRS adapter   for connecting Dayton with usb audio adapter.
6. An external dac/amp with volume control connected to another one of your computer’s usb ports (I use the Schiit Fulla or Audioquest Dragonfly with a volume-wheel added, but could also use the Shanling M0, for example).
7. A sound meter like this one…there may be phone apps, too.
8. A 3.5 mm male-to-male audio cable.
9. A coupler.

Here the specs of our coupler:

Disclaimer: The measuring coupler is two pieces of plastic tubing on the end of a Dayton iMM-6 microphone. No compensation or smoothing is applied. Our measurements should not be directly compared to other measurements except those done on the same device. 

• Inner tube: 10 mm long clear vinyl water pipe tubing, 5/16″ inside diameter, 7/16″ outside diameter
• Outer tube: 20 mm long PVC pipe, 7/16″ inside diameter, 1/2″ outside diameter
• Slide 5 mm of inner tube over end of Dayton IMM-6 mic (it helps to mark the tube at the correct position)
• Slide 5 mm of outer tube over end of inner tube.
• The internal volume of this ‘stepped’ coupler is 1.68 cc. ‘Medium’ tip sizes fit best.

You get the coupler ingredients from your local hardware store.

We typically insert the tips until the ends of the skirts are flush with the end of the coupler. This results in variable nozzle insertion depths with different tip/nozzle combinations – and therefore different driver-to-mic distances and remaining internal coupler volumes.  It is intended to mimic the effects of shallow- or deep-fitting IEM designs.

This is Our Setup Workflow:

1. Setting up preferences

2. Soundcard calibration, step I:  calibrating REW’s internal SPL  (SoundPressureLevel) 

3. Soundcard calibration, step II:  calibrating dac/amp and usb audio adapter 

If you purchase a USB microphone, you can skip steps 2 and 3. And that’s all, folks…always good to get the big picture right away. So let’s start with the preferences…

1. Setting up preferences

This is easy. You just copy the settings provided. Biodegraded has extracted them from discussion forums. And they work.

When you open the “Preference” panel you see the following tabs.

Only the two underlined tabs “Soundcard” and “Analysis” need to be modified by you – the other five tabs remain untouched.

This is the Soundcard preference panel. All you have to do is inputting the numbers and input/output devices seen in this screenshot. The input volume should be 0.9. “Output device” is whatever dac/amp you have plugged in, and “input device” is whatever your computer calls the USB audio adapter. 

This is the Analysis preference panel. Just fill in these settings into your own window.

Note: the greyed-out Control output mixer/volume should be set at 0.500. We had some initial problems doing that.

And we are done with the Preference setup – close the pane. Wasn’t all that bad, was it?

But hey, why did we ignore the mic/meter tab? After all, our Dayton mic comes with a calibration file…shouldn’ we input it there? Well, no, apparently the measurement results are better without the calibration file.

2.Soundcard calibration, step I (of II):  calibrating REW’s internal SPL (SoundPressureLevel) 

https://www.roomeqwizard.com/help/help_en-GB/html/inputcal.html – top

Hardware setup:

Input: microphone -> TRS to TRRS adapter ->USB audio adapter -> computer’s usb port

Output: computer’s headphone jack and external speaker

The idea of this step is to tell the internal SPL what 85 dBs in real life is. For this, we need an external sound source. An 85 dB sound from the computer’s loudspeakers is recorded by the (in our case) Dayton imm-6 microphone. 85 dB is an arbitrary number that has proven to work well for measurements. The sound is generated with the REW software and output to an external speaker via the headphone jack and recorded by the microphone. When you hold your hand held sound meterside-by-side with the microphone, you can adjust the volume of the sound so that both sound meter and microphone record the desired 85 dB. 

1. After having connected all devices, open the SPLin REW. Select “Calibrate” and choose Signal Source “Use an external signal”. 

2. Next, select “Generator” to produce the sound.  Make sure, you got the right settings:

RMS level: -3.0

1000 Hz sine wave

Speaker: can be left or right, doesn’t matter

3.Now run the sine wave and adjust the volume on your amplifier (Fulla or whatever) until you measure 85 dB with the hand held sound meter. Place the microphone at the location where the sound meter reads 85 dB, adjust the internal SPL to 85 dB,  and then push “Calibrate” on the SPL meter windowto use external signal. 

Done! Now we have calibrated the internal SPL as part of the soundcard calibration. And you never will have to do this again for this hardware.

3.Soundcard calibration, step II (of II):  calibrating dac/amp and usb audio adapter

Hardware Loop:

First USB port (output) -> dac/amp à3.5 mm audio cable -> usb audio adapter -> second computer USB port (input)

We don’t need the TRS to TRRS adapter for this step.

This step produces a calibration file to be used in your soundcard preferences. For this we need an internal sound source. This calibration file is specific for this hardware arrangement and can be used each time you perform measurement. If you decide, for example, to use another amp/dac, you will have to create another calibration file.

1. Carefully double-check your soundcard preferences.

This is the same screenshot as the first one above.

There is a “Calibrate” and a “Make Cal” button in the Soundcard preference pane. What is the difference? 

The ”Calibration” is used first to apply the calibration file to the soundcard. “Make Cal” is the important one — used thereafter to create our calibration file. It is essentially the “save to file” button.

There is also a “Calibrate” button in the SPL window. NEVER EVER touch this one again  as you erase your microphone calibration of step 1.

And so it goes: Open Generator and SPL: produce a sine wave with the same settings as before:

RMS level: -6.0

1000 Hz sine wave

Press the “Calibrate” button in the sound preference pane and follow the steps that come up in the help window at the bottom. Choose -6 dB in the generator.

Adjust the volume of the dac/amp so that the SPL meter shows 85 dB (you remember that number from before). Let it run.

At one point, an automatic measurement will start and create a graph called “Soundcard”.

Push the “Make Cal” button in the soundcard, preference pane to save this curve to a file. At one point you will have to name this newly generated file. Give it a sensible name such as “amp name and audio adapter name”. For example, one of my calibration files is called “Audioquest Dragonfly and Trond.cal”. 

Congratulations, your soundcard is now calibrated and will never have to be recalibrated again for this hardware setup.

And if you exchange your Dayton microphone for another one, you will also NOT have to recalibrate the SPL meter again – as the error of any specimen of this model has more variation than our calibration error.

And now some window dressing…fine-tune your display window that will host your frequency response curves. 

Set axis limits for your coordinated system to 50 to105 [dB] and 20 to 20000 [Hz]: 

And done. Now we can focus on the measurements.

Performing Measurements

After performing the SPL and ‘soundcard’ calibrations described above (including loading your newly generated hardware calibration file in the soundcard preference pane: see image below), you’re ready to make some measurements. Because different headphones have different sensitivities, you’ll need to play with the volume on your output device (amp) to get the same level (85 dB SPL at 1 kHz) for each headphone being investigated. To do this:

1) Put the headphone/earphone on/in your microphone measurement coupler (e.g., our highly sophisticated plastic double-tube) and connect it to your output device (amp).
2) Open the Generator and adjust it to RMS Level dBFS -3; choose Sine Wave & 1000 Hz for the inputs and Speaker, L or R (corresponding to whichever ‘phone you’re measuring); and hit the ‘play’ button. 
3) Open the SPL Meter, hit the big red ‘record’ button, and adjust the volume on your amp until the dB screen reads 85.0.
4) DO NOT HIT THE ‘CALIBRATE’ BUTTON on the SPL Meter, or you’ll ruin all the good work you did in calibration step 1 above and will have to repeat it. Exit the SPL Meter and Generator.

Note that a common standard for headphone measurements is 90 dB at 1 kHz rather than 85 dB. We use the latter because we find with our setup that peaks in the frequency response (commonly the ones around 3kHz) any higher can result in clipping (overloading of the input), leading to the FR curve at the offending frequency being blunted or flattened (and the sound being distorted). Occasionally (e.g. with ‘Chifi chainsaws’) this also happens at 85 db. REW will warn you if it does. If so, use a lower level (e.g. 80 dB) at step 3 and try again. If you still get clipping at 80 we suggest there’s no need for any more measurements and recommend throwing the offending earphones away or using them to punish evil children rather than putting them in your own ears.

Result: the graphs of all measured earphones must intersect at 85 dB at 1 kHz.

Epilogue: Tips, Tricks, Techniques, Troubleshooting, and Pitfalls

Use the right tips correctly

1. Use medium-sized tips for this particular coupler.
2. Always use the same tips for your measurements. There is also room for measuring with the supplied tips. Compare the results of the two.
3. If measuring with narrow-bore and wide-bore tips, superimpose the graphs and record the differences. Try to find the general trend.
4. Before inserting, add a THIN layer of spit on the rubber to achieve better seal (slide works for ear canals).
5. Annotate your file with the tips used and other technical particularities.
6. Superimpose graphs of the earphones you compare: it is a very effective visualization.

What if your graphs lack bass?

1. If your measured graph turns out lacking bass, you may have inserted the rubber tip to deep into the coupler or the tips are too large.
2. Likewise, your tips are too small.

How to strive for precision between R and L earpieces

Precision is a measure of reproducibility.

1. I always measure the left earpiece first, then leave the amp volume unaltered, and insert the right earpiece into the coupler for the next measurement.
2. I alternate between left and right earpiece several times to make sure the measurements can be reproduced.

Why are my peaks clipped?

…because I measured above 85 dB at 1 kHz.

Why do I get this huge channel imbalance whereby both curves are parallel along the entire spectrum?

That’s a channel imbalance in your amplifier. Get another amp but don’t forget to create another calibration file for it (=repeat step II above).

Why do others get a different looking frequency graph for the same earphone?

1. They use a different coupler.
2. They use different software and/or settings.

The post Calibrating and Using a DIY Rig for Measuring Frequency Responses appeared first on Audio Reviews.