Jürgen Kraus, Biodegraded &#8211; Audio Reviews

You find an INDEX of all our earphone reviews HERE.

The sound of the IE 500 PRO can be described as the slightest of a U: butter smooth, warm, organic from the low to the high end.

The low-end is absolutely gorgeous: it has a realistic speed (decay not too fast), and is well extended and well controlled right down to the lowest frequencies. Texture and resolution are superb and there is always a subtle rumble underneath the pleasantly warm bass. Mid-bass features a slight punch which my ears got used to quickly, it is not overdone, although still boosted above neutral. Some might say, the bass is not very impactful and deserves a more forceful attack, but this works out positively when turning up the volume in professional applications. Audiophiles may find the bass too strong, others too weak. Best low end I have heard in an earphone. Sugar!

Midrange is also above neutral, warm, and smooth, but it is not the most dynamic. The lower midrange is slightly recessed and male voices, while being well sculptured with nicely smoothened edges, could be firmer, denser, and with more energy and sparkle — in this class. Some people could find such male voices somewhat lifeless. The reason lies partly in the upper midrange which is somewhat dialed back. This also results in warmer and darker female voices and an overall more relaxed presentation, and it also introduces dullness. High piano notes may be affected as well as female voices, which could be richer, less veiled, and with more life. The upper midrange was probably toned down in order to avoid sharp, edgy voices and guitars, especially at higher volumes in professional use. At low volumes, the old Sennheiser veil shows at times, probably because of combined upper-bass bleed and the attenuated upper mids. Speech intelligibility is outstanding, though. Overall, the midrange deserves more body but that’s probably the tradeoff when attempting to optimize a single dynamic driver. Although it is claimed that the IE 500 PRO is a midrange-forward earphone (for vocalists and guitarists), just the opposite is the case and the midrange is actually weak — and undermines its purpose in my opinion.

Lower treble is also smooth and and never overbearing: it always remains subtle, maybe too subtle. Cymbals are clear and nicely decaying — but they lack attack. A 13-15 kHz peak adds some air and possibly some pretend resolution to compensate for the lacking upper midrange/lower treble. The overall treble with strong upper and subdued lower is therefore odd.

Timbre is a complicated topic with the Sennheir IE 500 PRO: it refers to tonal accuracy, which is not given in the suppressed midrange. Nevertheless does the sound beat any hybrid or multi I know in terms of degree of “organic”, “cohesive”, and “natural”. And here’s where my skepticism starts: at the technicalities. I can’t find the image particularly clear or even holographic as claimed elsewhere (the $116 Simgot EM2 do a better job in this respect), something I thought would set a $600 earphone apart from a $100 or $200 earphone. Spatial cues is also good but not outstanding. The soundstage is not particularly wide either and less deep (but deep enough; call it oval). Resolution, layering, separation are all good but as limited as you would expect from a single dynamic-driver earphone. Don’t get me wrong, these technicalities are all fine but simply nothing special. I would like to see a much bigger stage with a better detail resolution at this price.

PROFESSIONAL USE

Sennheiser recommend their IE 500 PRO to professional stage musicians. What works well for them is the low harmonic distortion. While the earpieces are small and inconspicuous, and the isolation is ok, the cable can tangle quite easily, in fact it tangles up all the time, and it takes patience to unwind, something a musician may not have. I also wonder why, in a sweaty environment, a white colour was chosen for the cable’s plastic coating. And I find the cable segment between earpieces and splitter somewhat flimsy. In this respect, I actually prefer the softer, more pliable, more rugged appearing, non-tangle “round” cable that comes with the IE 40 PRO.

A professional in-ear-monitor deserves a robust metal jack and not this basic rubber one. The proprietary earpiece connectors, on the other hand, are sturdy and work well but this does not leave you much of a cable choice. I speculate, most of these IE 500 PRO will not be picked up by professional musicians.

COMPARISON WITH THE ULTIMATE EARS 900s

The UE900s ($399/$179 on sale), which sports 4 Knowles balanced armature drivers, excel in their technicalities such as clarity and detail resolution. The IE 500 PRO are more cohesive, organic, natural, and smoother sounding. They have a less boosted but better resolving and more realistic low end. The UE 900s also are behind in terms of their less high soundstage, bigger dip in the lower midrange, and their larger harmonic distortion.

COMPARISON WITH THE SENNHEISER IE 40 PRO

The IE 500 PRO is marginally easier to drive with better resolution, imaging, and clarity. It features a more controlled and less boosted bass than the $99 IE 40 PRO [review], which brings its lower midrange a bit more forward in comparison. However, the IE 500 PRO lacks upper midrange/lower treble in comparison. The smoother IE 500 PRO has more depth and better rendered male and female voices (although not by much), and it lacks the IE 40 PRO’s upper treble peak that translates to high-frequency sibilance some are sensitive to. It also has a deeper stage, the IE 40 PRO’s appears more two-dimensional.

VALUE AND CONCLUSIONS

The Sennheiser IE 500 PRO (Made in Germany) lists at 599 USD/EUR. As a reference we have the smaller sibling Sennheiser IE 40 PRO (Made in China) that retails at one sixth at 99 USD/EUR. Considering that the differences in build and accessories are essentially zero [even the packaging is almost identical], the IE 500 PRO’s price justification must lie mainly in the driver, that is sound, and quality tolerances, and possibly in R&D cost. My problem is that the sound-quality differences between the two are not all that big in my opinion, certainly not by the factor of six.

Sennheiser IE PRO Series Models IE 40 PRO, IE 400 PRO, IE 500 PRO – What’s The Difference?

When questioning the price difference between the models, I received the following reply from Sennheiser Germany: “…The market around the IE 40 Pro were already really overcrowded, so that we have decided to enter that price point with a much, much better sound as typical products offer at this price point…”.

I wonder whether Sennheiser pursues a market segmentation in their pricing: different strokes for different folks? The 99 USD/EUR IE 40 PRO appeals to people who want a deal and get satisfaction, because the sound differences are relatively small and the price is right. And then there are the consumers who get satisfaction for not having made compromises and don’t mind diminishing returns. Or Sennheiser wants to milk professional musicians who are used to pricey equipment.

What speaks in favour of this is the “crazy” pricing of the rather basic twisted cable [79 USD/EUR], which is almost as much as the whole IE 40 PRO. If my speculation is right, I don’t understand why the IE 500 PRO did not receive a substantial material upgrade over the IE 40 PRO — are Sennheiser not aware of their (Chinese) competition? On the other hand, Sennheiser have to be consistent with their pricing and position the IE 500 PRO somewhere between the IE 800 and IE 80, which are both enormously overpriced in my opinion.

Fun while it lasted: although it will hurt returning the IE 500 PRO to Sennheiser (I really like them), I personally would never pay the asking price (or anything above $200) but will be perfectly happy with the well-priced IE 40 PRO instead. My pain is your gain: since this rather pricey review unit was not a gift horse, I could and did have a good look in its mouth. Please keep this in mind when reading other reviews of this earphone or of the even pricier competition.

In summary, the Sennheiser IE 500 PRO is a good sounding, well fitting, but not overly elaborately built or accessorized earphone that is priced out of contention. Sennheiser may have to come down from their high horse to stay competitive.

Sennheiser IE 500 PRO Brief Second Opinion

By Biodegraded

Pros — Fit, comfort; isolation; bass (good level, good timbre); easy to drive

Cons — Tonality (upper mids & lower treble missing in action); cable (nothing special, has proprietary connectors); price.

In my earlier review of the IE 40 Pro [review], I expressed hope that the IE 500 Pro would fix some of the cheaper model’s tonal shortcomings. Well, no. Although the bass of the IE 500 PRO is toned down relative to the IE 40 PRO, the overall tonal balance is an even more extreme version of the ‘stage monitor’ pattern, with upper mids and lower treble being even more recessed.

Starting with the positives, the bass on these is the strong point: not too overdone relative to the lower mids, and having fast-enough transients while still retaining an organic smoothness. Beyond the bass, however, things start to get less satisfying. Although the lower mids are at a level commensurate with the bass, the upper mids are recessed to the point where the higher harmonics of low to mid male vocal and low-note instrument signatures are heavily suppressed, which gives the fundamentals an odd and unrealistic timbre. Moving further up the range, female vocals, piano notes, high-note strings and horns sound even less natural because of the recession in the low treble. Further up still, cymbals sound really odd because the lowered low treble combines with a lift in the mid-treble in a way that suppresses the initial hit but accentuates the shimmer, so I’d hear the latter but be left wondering where it came from.

I won’t comment on the technicalities of these, because, frankly, I found the tonality so distracting that I’m not convinced about my impressions of any of their other aspects. And I probably didn’t listen for long enough.

In conclusion, these are not earphones that will appeal to people for whom neutral tonality is high in their list of must-haves. I also think they don’t succeed well in their aim to be a high-resolution stage monitor, because the heavily suppressed upper mid / lower treble affects perception of the tone of the lower midrange so that a musician’s ability to “reliably locate themselves in the mix and hear every nuance of other voice or instrument, even on the loudest stages” (from Sennheiser’s marketing material), would seem to me to be compromised. If you’re a drummer, a bass player, or Leonard Cohen this might be ok, but otherwise the $99 IE 40 Pro does a better job at this.

Contact us!

DISCLAIMER

This 30-day loaner of the Sennheiser IE 500 PRO was supplied by Sennheiser USA for our independent reviews. Sennheiser Germany were responsive to JK’s questions. We thank them very much.

The post Sennheiser IE 500 PRO Review – Flagship! appeared first on Audio Reviews.

Kinboofi MK4 Review – Famous Soon?

Jürgen Kraus, Biodegraded — Fri, 07 Jun 2019 06:01:01 +0000

by Jürgen Kraus

Pros — Audiophile tuning; good tonal accuracy; very easy to drive at 22 Ω ; hand-crafted shells; high-quality MMCX connectors; great cable.

Cons — Large earpieces; meager accessories.

You find a series of detailed photos showing the anatomy of the Kinboofi MK4 on our blog HERE.

EXECUTIVE SUMMARY

A well-resolving, mostly neutral (but never sterile) sounding earphone with a tepid low end.

INTRODUCTION

Kinboofi is a Chinese junior company with an unusual sounding name so cryptic that even Kinboofi could not tell me much about themselves in their humbleness. I contacted them via their amazon store to get some basic information, but all they had to say was that they didn’t have a “famous history” and that they wanted to be as well known as Knowledge Zenith. Quite frankly, Knowledge Zenith likely do presently not offer a model that can sonically compete with the MK4.

SPECIFICATIONS

Product Name: Kinboofi MK4 4BA In-ear Earphone
Type: In-ear
Drive Unit: 4BA Balanced Armature drive unit each side
Impedance: 22 Ω
Headphone Sensitivity: 116 db
Frequency Range: 20-20 kHz
Interface: 3.5mm
Cable Length: 1.2 m ± 5 cm
Color: blue
Cable: Silver-Plated, no mic
Earphone Interface Type: MMCX connector
Price: $259 (at the time of this review)
Product Link: Wooeasy Earphones Store

IN THE BOX…

…are two identical (but differently coloured) sets of eartips (S, M, L), cable, earpieces, and a small case.

PHYSICAL APPEARANCE, HAPTIC, AND BUILD QUALITY

The beautifully and sturdily built resin earpieces are rather large but fortunately also quite light. The included pearly white six-core silver-plated copper cable is extremely soft and flexible and has zero microphonics (but also no chin slider). It feels silky smooth between the fingers. I usually don’t care much about cables but this one is great. The MMCX connectors are robust and of a higher grade than the ones I had experienced previously. They were tight to begin with so that I had problems getting the cable connected for the first time. And after numerous forced dis-/re-connections, the connectors remained tight and precise.

ERGONOMICS, COMFORT, ISOLATION, AND FIT

Despite their large size, the earpieces are comfortable and, depending on insertion depth, isolate well.

SOURCE AND EARTIPS

The Kinboofi MK4 were very easily driven by my iPhone SE at their 22 Ω impedance. In fact, adding the Audioquest Dragonfly dac/amp created amplification overkill. The largest relatively long and slim included green-and-grey eartips worked well for me.

TONALITY

The low end has a flavour somewhat between a BA and DD in terms of composition and speed. It is not particularly textured but rather linear and adds a bit of warmth to the otherwise more neutral overall image. Call it tepid. The low-end is definitely above neutral, though not by much. It is well extended and stays reasonably well composed all the way down. Luckily, the mid-bass hump of so many dynamic drivers is missing and the slam of a more or less realistic magnitude comes from the lower-bass/sub-bass transition. The low-end is quite pleasant to my ears and develops sufficient impact to please — without being “too much”. Nevertheless, changing tips can generate a different bass perception. For example, the largest tips included with the Moondrop Kanas Pro [review] created an almost boomy bass. Results may vary from ear to ear.

The lower midrange is slightly recessed, close to neutral, and therefore not at the upper end of the “richness” spectrum. Male voices are rendered realistically but are not particularly warm. Female voices are well sculptured and with good air, and they can be still slightly back to reasonably intimate. The upper midrange is relatively smooth and does not develop a general harshness but it can be a bit overwhelming at times. The whole midrange is characterized as close-to-neutral with great speech intelligibility and resolution. I find the transition from the low-end (from warm to neutral) could be a bit smoother.

Treble can be somewhat inconspicuous. Cymbals and snares can sound realistic in some pieces and plasticky and grainy in others. The Kinboofi is certainly not a treble-forward earphone but also none with unpleasant peaks. Nevertheless do the upper treble peaks create some air and possibly some fake resolution.

Soundstage has a good width with some depth and it is rather high. As a difference to cheaper earphones I have tested, the stage is simply bigger with better spatial cues. Resolution is excellent and better than in any of my $100-150 earphones tested: high and low notes are separated well (e.g. Rammstein’s rhythm guitar on the low end and keyboard at the high end). Micro-resolution in the treble may be lacking a bit. Violins develop great micro detail I can’t hear in cheaper models.

Timbre is good albeit not quite as organic as it could be. The Kinboofi MK4 does sound like a BA earphone, which is less organic than, for example, the new Sennheiser IE 500 Pro single DD. In comparison to $100 earphones, the Kinboofi have a more substantial image and more of a concert hall feeling to them. I also find that the MK4 as well as my Ultimate Ears 900s start distorting at relatively low volumes, whereas I can turn up the single DD Sennheiser IE 40 PRO ad infinite, but this is a general BA issue.

CAN THE KINBOOFI MK4 BEAT MY ULITMATE EARS 900s?

I don’t have many earphones in the Kinboofi MK4’s price range to compare them to, but coincidently the $399 Ultimate 900s [occasionally $179 at Massdrop] are one of my go-tos. The UE900s also sport 4 BA drivers (all by Knowles] stuffed into much smaller earpieces than the Kinboofi MK4’s, which are connected by a selection of two terrible-quality cables. The more neutral MK4 present a more natural midrange against the smoother, more coherent but also more coloured UE900s. The MK4 also have a better build, a higher soundstage, whereas the UE900s have superior imaging, separation, and resolution. Bass is of a more BA-type for the UE900s, but very well executed…very dry…and more textured than the Kinboofi MK4’s, but also more boosted. Both earphones don’t have any part of their frequncecy spectrum overly exaggerated, which makes each of them good a non-fatiguing listen that should appeal to both the fun crowd and the analytical crowd alike. The MK4 work for me for many genres from classical, jazz, through rock and pop.

But to answer the question: there is no clear winner, both earphones, the UE900s and Kinboofi MK4 are certainly in a similar sonic league imo.

CONCLUDING REMARKS

The Kinboofi MK4 have passed my test. Who may think the name Kinboofi rhymes on goofy will stop laughing soon when the company will be a household name. Kinboofi may not be as big as Knowledge Zenith but they certainly have a product in the MK4 that is arguably superior. In today’s world, where a $200 earphone has become as disposable as a bottle of wine, the beautifully handmade Kinboofi MK4 could be a good candidate for a go-to earphone with a long shelf life.

KINBOOFI MK4 QUICK SECOND THOUGHTS

by Biodegraded

Pros: Build, cable, even tonality, easy to drive

Cons: Bulk, incoherent timbre, sensitivity to amplifier impedance

The tonal balance of these is good, without the overemphasized bass or elevated treble of many Chinese earphones. The treble though can tend to hissiness and sibilance on revealing recordings. The quick-decaying BA timbre is very noticeable, particularly in the highs, and it seems that the multiple drivers don’t play together very well, giving a sense of incoherence. I couldn’t decide if it was that or if it was true distortion that gave rise to a fuzz that I know isn’t there in certain mid-centric guitar riffs, but the effect was disconcerting.

Also disconcerting was the impedance profile. With impedance varying >5x from a low of 5 ohms around 10 kHz to a high of 56 ohms in the midrange, these will react strongly to the output impedance of the amplifier they’re driven with. In the plot below, compared to an assumed zero impedance reference in red, the frequency responses with amps of >3 ohms (blue; ‘iEMatch’ output of ifi Nano BL), 5 ohms (purple; older iPhones), 10 ohms (teal; some Topping amps) and 23.5 ohms (tan; SE output of Loxjie P20) show increasingly darker tilts: bass and lower mids up, treble down. I spent most time listening to these with the Audioquest DragonFly Black (< 0.5 ohms) and my phone (1.2 ohms).

Despite their bulk, I found these comfortable to wear for extended periods and with the stock tips I found they isolated well. Like a lot of recent ‘budget’ and ‘mid-range’ Chinese-made IEMs, the supplied cable is excellent and together with the solid construction gives the impression that these are serious iems.

In conclusion: I liked the tonal balance, but not the BA treble timbre and the multi-driver lack of coherence, and whatever was causing the midrange guitar fuzz. I worry too that people with different amps (or phones) will hear these differently; on the other hand, if you have amps with rather different impedances, you might enjoy the differences in tonality they’ll provide.

DISCLAIMER

The pair of Kinboofi MK4 was supplied by Wooeasy Earphones Store for our independent reviews. Thank you very much.

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

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Calibrating and Using a DIY Rig for Measuring Frequency Responses

Jürgen Kraus, Biodegraded — Mon, 20 May 2019 06:01:51 +0000

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:

A computer with external speaker(s).
The REW software (free download: https://www.roomeqwizard.com).
A USB microphone OR a calibrated measurement microphone (like this Dayton imm-6).
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).
A TRS to TRRS adapter for connecting Dayton with usb audio adapter.
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).
A sound meter like this one…there may be phone apps, too.
A 3.5 mm male-to-male audio cable.
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)

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

Measurements Setup

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

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

What if your graphs lack bass?

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.
Likewise, your tips are too small.

How to strive for precision between R and L earpieces

Precision is a measure of reproducibility.

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.
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?

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

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

Sennheiser IE 40 PRO Review – Instant Classic

Jürgen Kraus, Biodegraded — Fri, 26 Apr 2019 04:04:17 +0000

REVIEW BY JÜRGEN KRAUS

Pros — Exceptional sound quality: cohesion, balance, and timbre; high-quality build; smooth, robust, full sound; great isolation and fit; outstanding value.

Cons — Grainy upper treble; flimsy pouch.

EXECUTIVE SUMMARY

The Sennheiser IE 40 PRO is a warm and cohesive sounding single dynamic driver (DD) monitor earphone that excels by its natural tonal quality. The image is built on a solid but never overpowering low end.

INTRODUCTION

My first headphone was a Sennheiser: I picked up the HD414 with its bright yellow pads from a flea market in Germany in the late 1970s — and listened to the Clash and Graham Parker & the Rumour, of course on vinyl. Heavenly! And since then, I have acquired another 7 pairs of Sennheiser headphones and as many earbuds and earphones.

Sennheiser HD414

Sennheiser is a company based in lower Saxony, Germany, that rose from the ashes of WWII. Founded in 1945 by Prof. Fritz Sennheiser out of Hanover University, they have been innovative mainly in headphone and microphone technology since. The very competent Tyll Hertsens of innerfidelity.com once ranked Sennheiser as the world’s best headphone maker (“despite the odd screwup”).

Sennheiser certainly did well with their headphones; for example, the HD600 has been a perennial favourite since 1998. With the appearance of smartphones, Sennheiser introduced the CX300 earphones as an alternative to the buds that came with the phones. I saw their follow-up, the CX300B MKII, ranked somewhere as one of the 10 best headphone/earphone buys below $500 back in 2013. These CX300s had great speech intelligibility but an overly muddy bass. The next generation of Sennheiser budget earphones included the very popular and praised Momentum in-ear, which disappointed me somewhat by its rather recessed midrange. In recent years, Sennheiser had been a bit complacent for my taste, missing the rapid developments in the in-ear sector. For example, they have never produced a balanced armature (BA) driver (earphone). Sennheiser claim that a single wideband transducer produces a more natural sound than an array of BAs that introduce a crossover effect…and they may actually be right.

And while holding on to the single dynamic driver designed in-house, the Sennheiser IE 40 PRO is the lowest priced one out of a series of three: the IE 400 PRO and IE 500 PRO [review] are due to release in May 2019. These are true monitors aiming to musicians but they work equally well for recreational listening.

SPECIFICATIONS (from the Sennheiser website)

IN THE BOX…

..are the earpieces, a cable with proprietary connectors similar to MMCX that actually work (patent pending); 3 sets of quality rubber earth and 1 pair of foams, a cleaning tool (!) and a pouch that is too small for my liking.

PHYSICAL APPEARANCE, HAPTIC, AND BUILD QUALITY

The earpieces of my black review unit are made of softish plastic, similar to the material used in Sennheiser headphones. It feels smooth and so does the cable that has just the right tension not to be springy. The ear mold (“memory wire”) around the ears is thick and soft and sturdy. The cable is detachable (bonus) but the connectors are proprietary (patent pending) — and as opposed to MMCX connectors they are reliable. The eartips are made of the usual thick high-grade rubbers offered in Sennheiser iems. Overall, all plastics and rubbers use are of good quality and I trust the Sennheiser engineers that the materials have the usual longevity. These monitors offer a truly functional design.

ERGONOMICS, COMFORT, ISOLATION, AND FIT

The earpieces are small and rather shallow so that they fit perfectly into my ears without sticking out. The fit is terrific and the thick ear mold is not intrusive while holding the shell firmly in place. The cable has zero microphonics. Isolation is outstanding: if you don’t need these for your band, they will also work well on the city bus or a plane.

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Sennheiser IE PRO Series Models IE 40 PRO, IE 400 PRO, IE 500 PRO – What’s The Difference?

SOURCE AND EARTIPS

I did my listening with the iPhone SE and used the largest included rubber tips. At 20 ohm, the IE 40 PRO are very easy to drive.

TONALITY

You find an INDEX of all our earphone reviews HERE.

The big picture: The IE 40 PRO are warm and mildly bassy earphones characterized by their great tonal quality (timbre) and homogeneity. Gone are the dreaded Sennheiser veil and the associated darkness. The overall sound is extremely pleasant without any significant aberations.

The details: What stands out is the strongly reduced bass compared to previous Sennheiser budget models such as the Momentum in-ear, CX 5.00, and CX 300B Mk II. The IE 40 PRO’s low end has its biggest slam rather deep down between 40 and 100 Hz, and the frequency response remains almost linear and a bit forward inclined between 100 Hz through the complete midrange into the lower treble, where it starts dipping at 6 kHz but and it reaches its biggest peaks between 12 and 15 kHz.

The slightly elevated sub-bass and bass form the solid foundation of the tonal image (“Klangbild”). This healthy but never thick low-end adds the volume that makes the IE 40 PRO sound like a headphone. The bass is medium-fast decaying which contributes to the natural timbre and it adds warmth to the image. It stays focused at this level into the sub-bass. The upper bass enhances and colours the lower midrange (male vocals) but at the expense of some clarity and transparency. For the listener, the bass appears to creep up subtly without the classic mid-bass hump. Very pleasant to my ears.

The midrange is not recessed. Both male and female voices sound full and natural. The upper midrange is actually below neutral at the expense of brightness and energy in guitars and female voices. Speech intelligibility is outstanding.

The lower treble is well-dosed and yet well extended without any peaks that could introduce sibilance, harshness, or hardness. The sound is smooth right into the upper treble that compensate for the flat upper midrange and lower treble by introducing some but not too much sparkle and air. The 12-15 kHz area is rather emphasized compared to other single DDs (including the ones mentioned below), which brings cymbals forward — they can sound a bit grainy in some cases. Several others reported this “upper” sibilance” that affects notes high above the voices. But because the treble did not pierce and the bass does not thump, I could turn the volume up on the IE 40 PRO without regret.

The soundstage is average in width but has a good depth and height. Instrument separation and layering are great – but, quite frankly, I don’t really care that much as the timbre is the delightful part: a saxophone sounds like a saxophone, a cello like a cello, and an acoustic guitar sounds like a…you got it.

In summary, the sound is like “aus einem Guss” (extremely homogenous), never fatiguing, and in the end addictive for me.

SELECT COMPARISONS

Sennheiser Momentum In-Ear ($99): This highly praised and by no-means bad single DD model has an overcooked, thicker bass that pushes its quality vocals into the back and produces a somewhat veiled and muffled sound. A simple mod [instructions] brings the midrange forward, recovers some transparency, and reveals its true quality, but still does not produce the depth of the IE 40 PRO. Midrange and treble are similar between the two models with the upper treble being more forward on the IE 40 PRO. Fit of the IE 40 PRO is also better. Overall, the IE 40 PRO are a good step up from the Momentum in-ear.

Brainwavz B200 v1 ($120; discontinued): The original black B200 with their 2 BAs are an underappreciated jewel and one of my all-time favourites. Although both are tuned very similarly up to 3 kHz the B200’s midrange and treble (and therefore the overall sound) is much leaner than that of the IE 40 PRO and their low end is more focused on the mid bass. Where they differ substantially is from the upper midrange up, where the B200 starts dropping off at 3 kHz. Cymbals are less forward and voices are less full, more fragile, less three-dimensional and less natural in the B200 v1. The IE 40 PRO sounds fuller at higher volumes, where the B200 v1 get tinny. It lacks the full sound that makes the IE 40 PRO sound like a headphone. The Senns also handle dense instrumentations better. Nevertheless is the lean sound of the B200 v1. appealing. If asked which of the two I’d surrender, I’d say: none. Both are excellent and it is needless to rank them against each other (considering that one is off the market)!

Focal Sphear ($129): This single DD has a similarly great natural sound, a thicker, less extended and less focused bass bleeding into the slightly recessed and thinner mids, and also more modest treble. The somewhat V-shaped Sphear is less dynamic and darker. Nevertheless are the differences not gigantic and the Sphear’s timbre makes it a great earphone.

iBasso IT01 ($100): The single DD IT01 has a more extended bass, which is nicely textured, but also a tad too strong for my liking. It smears into the lower midrange at the expense of clarity – which bugs me every time I use them (as they are very competent earphones in most other aspects). The vocals department of the Senns is cleaner, richer, and more homogenous wheras the iBasso’s may have more depth but it is also more recessed. In terms of natural sound, there is not much between them. The iBasso’s shells are much bigger and its fancy braided however heavy cable may be more appealing to some. Again, the Senns are more streamlined and pragmatic in this respect: everything works well together.

CONCLUDING REMARKS

I have rarely had a product come through my hands that was so well thought out and balanced as the Sennheiser IE 40 PRO, from the haptic, isolation, comfort, and fit to the sound. The IE 40 PRO’s strength is that it is just really good in most respects — and it hits a sweet spot, price wise. This is the rare case where I consider going out and buy myself a pair for the commute.

Es lebe das dynamische Treibersystem | Long live the dynamic driver!

DISCLAIMER

The review unit was a loaner sent upon my request with Sennheiser Electronic GmbH & Co KG in Wedemark, Germany, through Sennheiser USA. Dankesehr and thank you everybody involved! The sole purpose of this review was our independent evaluation of the IE 40 PRO’s technical and sonic qualities. Biodegraded used the same unit for his second opinion.

SECOND OPINION BY BIODEGRADED

Pros — Fit, comfort, isolation, cable (strong, flexible, quiet); bass (over-emphasized, but done well).

Cons — A bit recessed in the upper mids, treble spike (highs are grainy/scratchy); connectors are proprietary.

In the marketing material for these, Sennheiser pushes the ‘stage monitor’ focus, and stresses their ‘expanded sound spectrum’ vs alternatives with ‘multi-way drivers’ (presumably meaning the multi-balanced-armature units more typically targeted at performers). These two aspects are evident in the IE 40 PROs’ tonality: a downward-sloping frequency profile reminiscent of other ‘pro’ IEMs like Westones, but with the addition of a spike in the treble to complement the elevated bass (see JK’s measurements above).

People used to a stage-monitor style presentation might initially be impressed: coming from a dynamic driver, the elevated bass has good punch and timbre and goes deep, and the treble spike might initially give the impression of resolution. However…

Ok, the bass IS good. For me, it’s the highlight of these. It’s boosted a few dB, but it also extends deep, doesn’t seem to overwhelm the lower mids too much, and has dynamics and transients that sound natural. This, together with the isolation (good, but being rear-vented not quite as good as non-vented BA competitors) would be good in the noisy environments of a stage or a plane. The treble, though, is a let-down. The narrow peak (around 12 kHz in JK’s measurements) is too high and its timbre is unrealistic, rendering a grainy or scratchy texture to cymbals and high violin notes. For me, this is a deal-breaker.

The upper mids are also a bit low. People sensitive to emphasis in the 3-5k area (JK’s ‘ChiFi chainsaw’) might not mind this, but I found the suppression in this region coupled with the treble exaggeration to negatively affect my perception of instrument separation and imaging – for me, another minus.

If you can get over the treble, construction, fit, and as noted above, isolation, are very good. The cable is a particular highlight: strong, flexible, and almost completely non-microphonic. The connectors, while easy to plug in and out, also seem strong and flexible (they’re recessed into the bodies of the earphones for extra protection). Unfortunately the connectors are proprietary. I don’t know if after-market versions are available, but replacements direct from Sennheiser are $CAD 39.95; not too bad.

In conclusion, if you like (or thanks to background noise, need) a bit of bass boost and don’t mind or can’t hear the spiked and scratchy treble, these could be worth considering – and to repeat, the bass is good. Serious musicians who are considering replacements for or alternatives to multi-balanced-armature monitors in the few-hundred-dollar range, or studio buffs looking for a more neutral sound signature, however, should look elsewhere – perhaps at Sennheiser’s upcoming IE 400 & IE 500 models. These are also of single-dynamic construction, and at ~3.5x & ~5.5x the price they’ll hopefully address the IE 40 PROs’ shortcomings (audition before buying, of course!).

The post Sennheiser IE 40 PRO Review – Instant Classic appeared first on Audio Reviews.

Brainwavz Koel Review – Rip It Up

Jürgen Kraus, Biodegraded — Sun, 17 Mar 2019 15:48:12 +0000

This is a double review of the Brainwavz Koel: the first one by Jürgen Kraus followed by Biodegraded’s second opinion. Jürgen writes:

Pros — Great midrange and detail resolution; smooth sound.

Cons — Bass is light and ergonomics may not be for everyone; hard to drive; lacks dynamics.

INTRODUCTION

A bit over a year ago, I read an article on the latest balanced armature earphones from Brainwavz and ordered the now discontinued B100. It had been lauded by headflux.de for its tuning details: for its good cohesion, slight warmth, relaxed sound, and particularly for his lack of a grossly exaggerated bass (rather rare in this price segment at the time). Apart from that, it is small and comfortable. I ordered them and found all to be true. A few days ago, I used them on a Transatlantic flight for watching movies and listening to music, and I still like them a lot.

I also purchased the now discontinued B200 v1. which is optically indistinguishable from the B100 but it sounds a bit rounder at the low end and has a better resolution. In fact, I find the B200 v1, so well tuned that I claim it is the almost perfect earphone for meminus the resolution of the >$1000 models. I also tested the slightly ”fatter” sounding B400, which is technically even better but has a different tuning: it is warmer through a prominent bass hump and may have a broader appeal. All Brainwavz models belong to the best my collection can offer and I was therefore keen on trying out the Brainwavz Koel, which follows the B400 and revised B200 in that it features a 3-D printed shell.

SPECIFICATIONS

Model: Brainwavz Koel

Driver: Single Balanced Armature

Rated Impedance: 30 Ω

Frequency Range: 16 Hz ~ 22 kHz

Sensitivity: 105 dB at 1 mW

Cable: Detachable

Cable Connector: MMCX

Plug: 3.5 mm, Gold plated

Warranty: 24 months

Price: $69.50

IN THE BOX…

The content is Brainwavz standard: earpieces, six pairs of silicone tips, one pair of Comply foam tips, standard cable, cable tie, shirt clip, and a sturdy hard case. Note: three pairs of tips (S,M,L) should have narrow bores and the other three wide bores according to the included manual; however all tips had the same narrow bores.

PHYSICAL APPEARANCE, HAPTIC, AND BUILD QUALITY

Brainwavz claims that the shells are “state of the art liquid resin 3D printed”. Their general build is the same as the current B200 and B400 models. The translucent housings are optically reminiscent of cough lozenges and have received a mixed reception: some find them downmarket and others a novelty. To me they are barely adequate considering the competition’s fine CNC-machined housings. The detachable MMCX cable is also standard Brainwavz and of good, proven quality. I like the connector angled at 45°.

ERGONOMICS, COMFORT, ISOLATION, AND FIT

I was initially struggling with the shallow insertion depth paired with the light bass (see tonality). I frequently thought I could achieve a better seal and therefore more bass (extension) by pushing the tips deeper into my ear canals…thereby only pushing the earpieces senselessly against my outer ear generating discomfort – but I had always reached a good seal before doing so. In the end I got used to the ergonomics, and comfort and isolation are actually quite good. Nevertheless do I question the size of the earpieces that only host a single balanced armature driver. I am not sure whether this is a requirement of the 3-D printer or a gimmick to make the Brainwavz Koel equally flashy as the numerous multi-driver competitors in its price class. The discontinued B100/150/200 v1. all had the same tiny and light shells which make them still favourites in my daily earphone choices.

SOURCE AND EARTIPS

I used my iphone SE and the largest included eartips – which are identical to the ones included in all B-series models. The Brainwavz Koel needs some power – it is not the easiest earphone to drive.

TONALITY

JK’s Test tracks

The big picture: The Brainwavz Koel is a slightly warm and smooth sounding earphone, characterized by a mature and refined midrange and an overly light bass and treble. It lacks major flaws such as unwanted peaks above the lower midrange but also dynamics. And it is hard to drive. The tuning is characterized by an inverted U-shape of the frequency response curve, which is unusual and therefore interesting in this price range. The Koel is tuned to sound more expensive than its class peers – and Brainwavz did a decent job with this. Its most outstanding characteristics is its excellent detail resolution. Midrange and resolution are a step up from the discontinued Brainwavz B100.

The nitty gritty: Yes, the midrange is the shining star of the Brainwavz Koel. Voices are clear and well defined, and they are reasonably intimate but never overwhelming. They are not the thickest but that is in most cases not needed in the context of bass and treble. The midrange is emphasized by a wide but shallow soundstage, the sonic equivalent of a wide-screen movie…the image is stretched in the horizontal with a linear frequency response across the upper bass and lower midrange. This midrange also provides for a very pleasant timbre and an enjoyable overall image. The little peak at 3 kHz, similar to the B200 v1., helps shape the vocals, which shows the good quality of the driver.

The bass is nicely controlled with a realistic decay, but way to subtle and light and not well enough extended for my taste. It starts rolling off at 200 Hz and more dramatically so at below 100 Hz. This removes both dynamics and depth from the soundstage for the benefit of the vocals, which somewhat make up for it. As a result, the low end lacks slam and punch and registers as “below neutral”.

The roll-off at the upper end starts already in the upper midrange at just above 3 kHz, and a mini-peak at 14 kHz adds sparkle and fake clarity and resolution. This early rolloff is similar to the praised B400. The Koel renders high piano notes reasonably well, although they could be a bit more forward. I also found some cymbals deserved a bit more volume and a slower decay. I take it the roll-offs at either end are the price to pay for “tickling” this terrific midrange out of a single BA driver.

What I found outstanding was the Brainwavz Koel’s detail resolution, separation, and layering. Typically, budget single-driver earphones have problems with dense instrumentations such as a symphony orchestra, which can result in a congested midrange. Not so the Koel which mastered classical ensembles quite well.

I was working with two pairs of the Koel and each of them had a pronounced channel imbalance in that each right channel was lacking 3-5 dB compared to each left channel between 20 Hz and 3.5 kHz. I repeated the measurements multiple times and Biodegraded remeasured the first pair on his rig — and arrived at the same result. Considering our similar experience with three units of the B400 I wonder whether this is a systematic production issue. It is in no case acceptable and should be fixed instantly.

JK’s frequency response of the first pair of Koels.

JK’s frequency response of the second pair of Koels.

And whereas all of the above may be grey theory, the Koel performed well with most of my test songs.

Queen’s Bohemian Rhapsody live at Live Aid Wembley was rendered with a good sense of space; you feel you are there. This was hard to achieve with other budget earphones.

Impressive was the vocal separation between the King’s Singers and Albrecht Mayer’s oboe reproduction in Humperdinck’s “Abends wenn ich schlafen geh” (from the opera “Hänsel und Gretel”). Most of my earphones, independent of price, have problems with this, not so the Koel.

Louis Spohr’s nonet in F, Op. 31, confirmed the great detail resolution, layering, and instrument separation as well as the timbre of natural instruments.

Toto’s “Africa” is a good test for a bloated bass, and “99” has a built-in filter for identifying a shouty upper midrange. The Koel mastered both very well.

David Byrne’s hard to reproduce “everyday is a miracle (live)” was finally bringing the Koel to it limits: Byrne’s voice could have been somewhat denser and the chorus revealed a bottleneck (instrument crowding) in the upper midrange, which is handled smoother by more expensive models.

But any music that required some punch and energy from the low end such as by the Pixies or Metallica came across as much too polite for my taste. BTO’s “Four Wheel Drive”, a gritty piece of hard rock representing the famous “Winnipeg sound” with Garnet amps and Randy Bachman’s Gretsch guitar was being refined to créme mousse lacking any pizzaz.

CONCLUDING REMARKS

The Brainwavz Koel shines in some aspects but completely fails in others. It excels by its cohesive however little dynamic sound generated by its single balanced-armature driver. Nevertheless, its sound is not balanced in that particularly the low end suffers greatly from the lack of life. The Koel does a good job with classical or vocal music but may not reproduce rock music convincingly for many.

The Koel also fails to take ergonomic advantage by not featuring a substantially smaller shell than their driver-loaded competitors. With the Koel, you also get an earful, literally. I am missing the B100/150 design in this respect.

In summary, with the Koel, Brainwavz have refined and moved their budget BA segment into line with their higher-end models such as the B200 and B400. However this step forward was accompanied by at least one step back. The ergonomically better but technically less capable B100 may have had a less sophisticated midrange but it had the right dose of punch and depth above a robust low end — something that is crucial for everyday listening.

On the other hand, Brainwavz have done a clever job by offering an earphone that essentially has no competitor in its class as it sounds unique. It is a pretender in that it mimics more expensive earphones – and it does it well while not being a universal earphone for everyone.

SECOND OPINION BY BIODEGRADED

Pros — Resolving mids, isolation; comfort (but the fit is odd).

Cons — ~3dB channel imbalance (systematic?); rolled off in bass and treble; poor dynamics; harder to drive than the impedance and sensitivity specs would suggest; odd fit (in my ears at least); tips not as advertised.

The first noticeable thing about these is the mid-centric frequency response. Together with the detail/resolution of the midrange this is pleasant, but when listening to music with a lot of bass and treble content, what’s missing is obvious. And while the resolution is good, the dynamics are slow, again making music with punch sound limp. Vocal/acoustic dominated material comes across well, however. Along with the rolloff, the timbre at both ends of the range is also unsatisfying. Bass is soft, and what treble is there has overly-rapid decay (which I think some people refer to as ‘plasticky’ texture), both characteristics likely reflecting the handicap of using a single BA driver.

Biodegraded’s frequency response and impedance of the first set of Koels. Note the good match with JK’s graph above.

Also obvious, and distracting, is the channel imbalance. My measurements mirror JK’s, with the right side being down ~3 dB from the left all the way through the bass and mids. That he found the same on a second pair raises suspicions of a systematic manufacturing problem – possibly different internal volumes of the 3D-printed shells.

Upper mids and treble will be influenced by the output impedance of whatever is used to drive these. The specifications give the Koel’s impedance as 30 ohms My measurement puts this around 500 Hz, with a rapid climb to about 150 ohms at 2.5 kHz, then a sharp drop, then a steady climb through the treble to more than 300 ohms. Higher impedance sources (e.g., some iPhones at around 5 ohms) will noticeably boost the ~2 kHz area and the mid- to upper treble. On brief comparison I thought I heard a bit of difference using the ‘iEMatch’ output of the ifi Nano BL (>3 ohm) vs the ‘Direct’ output (<1 ohm), but owing to the difficulty of matching levels I couldn’t be certain.

In conclusion: if you want something for vocal/acoustic music you might like these; BUT I wouldn’t buy them myself until I was sure that Brainwavz have improved their manufacturing process to deal with the channel imbalance. This was also an issue with the B400, measurements of 3 different pairs showing different bass responses and different degrees of imbalance there. This possibly reflects inconsistencies in the 3D printing process leading to enclosures having different volumes. It would also be nice if the right sets of tips were included. In short, there are QC problems here. I’d recommend buying from Amazon or another retailer that offers a full cash refund rather than exchange so you can get your money back if you find a problem and decide you don’t want to try another pair.

DISCLAIMER

The two review units were provided by Brainwavz as part of their Koel marketing campaign. The fast communication with Brainwavz is appreciated. The sole purpose of this double review was to independently test the Koel’s technical and practical capabilities. Following this review, we returned the two units to Brainwavz for their own analysis on 2019-03-27.