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Parent Category: Products

Category: Headphone Measurements

Created: 10 October 2021

Reviewed on: SoundStage! Solo, October 2021

I measured the 64 Audio Duo earphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. For most measurements, the headphones were amplified using a Musical Fidelity V-CAN amplifier; I used a Schiit Magnius amplifier for distortion measurements. I used the supplied medium-sized SpinFit silicone tips for all measurements because they fit best in the ear simulator. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

This chart shows the Duos’ frequency response. It’s pretty normal stuff. Reduce the output by a few dB at 200Hz (very difficult to do with a passive, two-way design like this) and you’d have something somewhat close to the Harman curve. There’s a big resonant peak at 17kHz. I can’t hear discrete tones at that frequency, and although I often can hear the phase effects of high-frequency peaks “leaking down” to lower frequencies, I can’t in this case. I’d guess that most females under 45, and most males under 25, will probably notice the effects of this peak—but I doubt they’re the target market for $1200 earphones.

This chart shows how the Duos’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop, some tube amps, or some professional headphone amps. Considering that the treble is handled by a balanced armature, it’s surprising to see so little difference in response when the source impedance is changed.

This chart shows the Duos’ right-channel response compared with the 64 Audio U6t, the Audeze Euclid, and the AKG N5005 earphones, the last in that list being the passive earphones that come closest to the Harman curve. You can see how the Duos’ bass is flatter than the U6t earphones’ bass, and how the treble is elevated above about 6kHz (I’d expected I’d see a peak at about 7kHz rather than shelved-up treble, but close enough). I’m very surprised to see how different the Duos and the Euclids measure, considering that I thought they sounded very similar. But with headphones and earphones, the effect of a peak in one area balancing or unbalancing the sound across the spectrum seems more extreme than it is with speakers, so weird things can happen.

The Duos’ spectral-decay plot looks very clean, with some resonance sneaking up from the bass region, but basically none above that.

Total harmonic distortion of the Duos is very low even at the extremely loud level of 100dBA.

In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. I added the U6t earphones because they’re similar in design to the Duos, but they’re not open-back—and it’s hard, from reading the marketing materials and looking at the product, to figure out exactly how “open-back” the Duos are. According to this measurement, the open-back effect seems to kick in only above about 3kHz, which I assume is where the dynamic driver starts to roll off and the Tia balanced-armature tweeter kicks in. Below 3kHz, the Duos offer only about 5dB less isolation than the U6t’s. Above 3kHz, the Duos offer 15 to 25dB less isolation than the U6t’s, so they definitely have some degree of “open-back-ness.” I included the Technics EAH-AZ70W true wireless earphones so you can see how a good set of noise-canceling earphones compare.

The Duos’ impedance curve is mostly flat at 7 ohms up to about 3kHz, and there’s only a little bit of variance once the tweeter kicks in, which is surprising because it’s a balanced armature, which would normally swing sharply upward in impedance as the frequency rises above a few kHz. Phase is flat below 3kHz, with only a very modest swing at higher frequencies.

Sensitivity, measured between 300Hz and 3kHz, using a 1mW signal calculated for 9 ohms rated impedance, is 98.7dB. That’s low for earphones, but not so low that you can’t get reasonable volume from most source devices.

Bottom line: Nothing to worry about with the 64 Audio Duos, their measurements are all safe’n’sane.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 01 October 2021

Reviewed on: SoundStage! Solo, October 2021

I measured the Sendy Audio Peacock headphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 QC audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. For most measurements, the headphones were amplified using a Musical Fidelity V-CAN amplifier; I used a Schiit Magnius amplifier for distortion measurements. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

This chart shows the Peacocks’ frequency response. This is not too crazy for headphones of this type, although with less bass output than I expected, but I guess the relatively mild 3kHz peak in the low treble balances that out. There’s more energy above 5kHz than I’m used to seeing; that combined with the low 3kHz peak might be how these headphones manage to deliver detail without seeming bright.

This chart shows how the Peacocks’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop, some tube amps, or some professional headphone amps. As usual with planar-magnetic drivers, there’s no significant difference.

This chart shows the Peacocks’ right-channel response compared with three other open-back audiophile headphones: the HiFiMan HE6se, the Audeze LCD-X, and the Dan Clark Æon 2, fitted with their optional perfed pads, which come pretty close to the Harman curve. You can see how attenuated the Peacocks’ bass response is relative to the others, and also how mild its 3kHz peak is relative to most of the others.

As with most planar-magnetic headphones, the Peacocks’ right-channel spectral-decay plot shows super-high-Q hash in the upper mids, in this case between about 1 and 3.5kHz—which I suspect gives most planars a greater sense of “air” and spaciousness. There is a very strong resonance around 7.3kHz, which corresponds with a cancellation/reinforcement peak in the frequency-response measurement, but the frequency and Q are so high that I doubt it’ll be troublesome.

Here’s the THD vs. frequency chart, measured at 90dBA and 100dBA (both levels set with pink noise). Distortion is negligible—a couple percent in the bass, but it’d need to be more like 10% to be audible at those low frequencies.

In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. I compared them with some other high-end models, and the Peacocks’ isolation is typical for their product category. I threw in the Audeze LCD-2 Closed-Back headphones so you could see how this compares with a closed-back design.

As is the norm with planar-magnetic headphones, the impedance magnitude is essentially flat, averaging 48 ohms, and the phase response is similarly flat.

Sensitivity, measured between 300Hz and 3kHz, using a 1mW signal calculated for 32 ohms rated impedance, is 101.1dB. That should be enough to get the Peacocks playing pretty loud with almost any source device.

Bottom line: The Sendy Audio Peacock headphones measure just fine. I see no technical concerns here.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 20 September 2021

Reviewed on: SoundStage! Solo, September 2021

I measured the Meze Audio Elite headphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 QC audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. For most measurements, the headphones were amplified using a Musical Fidelity V-CAN amplifier; I used a Schiit Magnius amplifier for distortion measurements. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

Because of the unusual nature of these headphones, and because I know readers may want a little more technical detail in this case, I’ve added some extra charts. Enjoy (I hope).

This chart shows the Elites’ frequency response with the part-leather/part Alcantara earpads. This is very much within the norm for open-back planar-magnetic headphones, although usually that big peak centered at about 3.5kHz would be shifted down by about 1kHz.

Here we can see the effects of the different earpads. Switching from the leather/Alcantara pads to the Alcantara pads has a big effect. Output below 800Hz is reduced by 2 to 12dB. Between about 2 and 9kHz, lower treble and mid-treble output is reduced by about 1.5dB on average. Above 10kHz, the top octave of treble is boosted by about 1.5dB on average.

This chart shows how the Elites’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop, some tube amps, or some professional headphone amps. As with almost all planar-magnetic headphones, there’s no significant difference.

This chart shows the Elites’ right-channel response (measured with the leather/Alcantara pads) compared with three other open-back audiophile headphone models: the HiFiMan HE6se, the Focal Utopia, and the Meze Empyrean. Other than a mild reduction in midrange energy from 800Hz to 2.2kHz, the Elites are similar to typical headphones of this genre.

Above is a comparison of the Elites with two headphones that come very close to the Harman curve: the Dan Clark Audio Æon 2 Closeds (fitted with the optional perforated pads) and the AKG K371s.

The Elites’ right-channel spectral-decay plot (measured with the leather/Alcantara pads) shows a strong resonance at about 330Hz, which may be the cause of the extra-punchy bass I noticed with these pads. That super-high-Q hash between 2.5 and 5kHz is typical with planar-magnetics, although there’s less of it than we normally see. My hunch is that this lends the headphones a greater sense of “air” and spaciousness.

Here’s the THD vs. frequency chart, measured at 90dBA and 100dBA (both levels set with pink noise). Basically, there’s no distortion, which is typical of planar-magnetics.

In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. I compared them with some other high-end models, and the Elites’ isolation is typical for their product category. I threw in the Dan Clark Audio Æon 2 Closed headphones so you could see how these compare with a closed-back design.

As we almost always see with planar-magnetic headphones, the impedance magnitude is nearly flat (averaging about 34 ohms) and the phase response is similarly flat.

Sensitivity, measured between 300Hz and 3kHz, using a 1mW signal calculated for 32 ohms rated impedance, is 96.3dB with the Alcantara pads and 97.7dB with the leather/Alcantara pads. So the Elites won’t really get cranking in the unlikely event you plug them straight into a smartphone, but they should perform well with any decent amplifier.

Bottom line: No red flags here—the Elites’ measurements correspond very well with my listening notes, and those were very positive.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 10 September 2021

Reviewed on: SoundStage! Solo, September 2021

I measured the Focal Celestee headphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 QC audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. For most measurements, the headphones were amplified using a Musical Fidelity V-CAN amplifier; I used a Schiit Magnius amplifier for distortion measurements. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

This chart shows the Celestees’ frequency response. While this is a little flatter than normal—which, with headphones, means they have a little more midrange energy relative to the bass and treble—I see no red flags here.

This chart shows how the Celestees’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop, some tube amps, or some professional headphone amps. It’s a significant change, with the high-impedance source increasing bass by 2 to 2.5dB between about 40 and 200Hz. This is due to the impedance swing you can see in the impedance chart below.

This chart shows the Celestees’ right-channel response compared with three other audiophile headphones: two closed-back, one open-back. Clearly, this response isn’t out of the ordinary for this product category. The Dan Clark Audio Æon 2 Closed headphones’ response is pretty close to that of the Celestees’, and both are not far off from the Harman curve.

The Celestees’ right-channel spectral-decay plot shows a strong resonance at about 3kHz, but it’s well-damped and likely below the noise floor within about 7ms.

Here’s the THD vs. frequency chart, measured at 90dBA and 100dBA (both levels set with pink noise). The distortion is low, maxing out at about 2% in the bass.

In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. I compared them with several high-end closed-back models, and as you can see, the Celestees’ isolation is typical for their product category.

The Celestees impedance magnitude curve has the bass resonance hump (in this case centered at about 90Hz) we usually see with dynamic drivers; phase is nearly flat.

Sensitivity, measured between 300Hz and 3kHz, using a 1mW signal calculated for 35 ohms rated impedance, is 104.1dB. Thus, the Celestees can deliver loud volume from almost any mobile devices that have headphone jacks.

Bottom line: The Celestees measure fine, and are well-suited for use with portable (and non-portable) devices. They’ll sound bassier with a tube amp.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 01 September 2021

Reviewed on: SoundStage! Solo, September 2021

I measured the Campfire Audio Honeydew earphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. For most measurements, the headphones were amplified using a Musical Fidelity V-CAN amplifier; I used a Schiit Magnius amplifier for distortion measurements. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

This chart shows the Honeydews’ frequency response. This is an unusual result in that the bass is substantially elevated relative to the treble, and instead of the usual big peak around 3kHz, there’s a dip. These earphones are definitely not going to sound trebly.

This chart shows how the Honeydews’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop, some tube amps, or some professional headphone amps. There’s no difference at all, because the impedance of the driver is unusually flat even for a dynamic driver.

This chart shows the Honeydews’ right-channel response compared with two other Campfire Audio products: the Satsuma and the Comet earphones, both of which use a single balanced-armature driver per earpiece, along with a stainless-steel sound tube similar to the one used with the Honeydews. The Honeydews are definitely the odd duck of this family.

This chart shows the Honeydews’ right-channel response compared with models from other brands: the dynamic-driver Sennheiser IE 300s, the Shure Aonic5s (a triple balanced-armature design), and the AKG N5005s, which are said to be the earphones that come closest to the basic Harman curve target response for earphones. The Honeydews have bass response similar to that of the AKGs, but the treble is down 10 to 13dB relative to the AKGs. Clearly, this is a very warm, bassy-sounding set of earphones.

The Honeydews’ spectral-decay plot looks clean, with just a bit of resonance in the bass and nothing of significance in the mids and treble.

Total harmonic distortion of the Honeydews is exceptionally low at the very loud level of 90dBA (measured with pink noise), but at the extremely loud level of 100dBA, it rises dramatically below 120Hz, up to about 13.5% in the deep bass. However, distortion at low frequencies isn’t very audible, thanks to the ear’s relatively low sensitivity at those frequencies; 10% is considered a good general guideline for the threshold of audibility of subwoofer distortion. Having measured distortion of a few hundred subwoofers, I can confirm that the Honeydews’ bass distortion would be only barely, and probably fleetingly, audible.

In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. As with the Satsuma earphones, the Honeydew earphones offer only average isolation when used with the included silicone tips. But the Honeydews are based on the Comets, which have some of the best passive isolation I’ve ever measured when used with their supplied foam tips, so out of curiosity, I tried the Honeydews with some similar foam tips, and the result was about as good as passive isolation gets with earphones.

The Honeydews’ impedance curve is effectively flat at 19 ohms, and there’s near-zero phase shift, which means the Honeydews’ sound won’t change with the input impedance of the source device.

Sensitivity, measured between 300Hz and 3kHz, using a 1mW signal calculated for 17.4 ohms rated impedance, is 112.3dB. That’s exceptionally high, so any source device can get high volume from the Honeydews.

Bottom line: The Honeydew earphones have a measured response that suggests a big, fat, warm sound. It’s a substantially different response than you’ll hear from most earphones. Whether that works for you is very much a matter of personal taste.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 10 August 2021

Reviewed on: SoundStage! Solo, August 2021

I measured the Sivga P-II headphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 QC audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. For most measurements, the headphones were amplified using a Musical Fidelity V-CAN amplifier; I used a Schiit Magnius amplifier for distortion measurements. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

This chart shows the P-IIs’ frequency response. Normally with open-back planar-magnetics, we see a more or less flat line up to about 1.5kHz, then a peak centered at about 3kHz, and another peak around 6 or 8kHz. The P-IIs have those characteristics, but they also have a reinforcement peak at 600Hz in the left channel and 725Hz in the right channel, with a corresponding cancellation dip. (I’m not sure if this difference in frequencies is due to a channel mismatch, or to the differences between the left and right ears on the 43AG.) I can’t recall seeing an artifact like this, and don’t know what it would sound like. The midrange rise at around 1.5kHz is unusual, although not unheard-of. There’s also an unusually strong peak around 11kHz, although I doubt this bothered my 59-year-old ears much.

This chart shows how the P-IIs’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop, some tube amps, or some professional headphone amps. As usual with planar-magnetics, there’s no difference—except at extremely high frequencies, where headphone measurements aren’t accurate or meaningful, and that might be a measurement artifact of some sort.

This chart shows the P-IIs’ right-channel response compared with three other affordable, open-back planar-magnetic models. It’s clear that the midrange artifacts of the P-IIs are something out of the ordinary, but what to my ears was more notable is the extra couple dB of energy at 3kHz, which is surely the cause of the subtle treble emphasis I sometimes heard. You can also see how unusual that 11kHz peak is; as I noted before, I doubt I heard it, but it seems quite possible that younger listeners might find it gives the P-IIs a somewhat bright sound. Or maybe it’ll make them sound airier.

More weirdness can be seen in the P-IIs’ right-channel spectral-decay plot. That is a very, very strong resonance at about 700Hz, which corresponds to what I measured in the frequency response. The Q of this resonance is very high, which would make it less audible, and I sure didn’t seem to hear any problems in this part of the audioband. The “hash” of high-Q resonances you see between 1 and 5kHz are common with planar magnetics, and probably caused by reflections between the flat-panel driver and the metal plate of the ear/cheek simulator; I’m not sure how much, if anything, they contribute to the headphones’ sound, but I speculate they might add a sense of air and spaciousness.

Here’s the THD vs. frequency chart, measured at 90dBA and 100dBA (both levels set with pink noise). As with most planar-magnetic headphones, distortion is extremely low.

In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. I threw in a couple of open-back models and one closed-back model (the Dan Clark Æon RT Closed headphones). As you can see, the P-IIs have the least isolation of any of the open-back models, which means you’ll hear more external sounds intruding on your music—so use them in a quiet place.

As with, I think, all the planar-magnetic models I’ve measured, the P-II headphones’ impedance magnitude and phase are both essentially flat.

Sensitivity, measured between 300Hz and 3kHz, using a 1mW signal calculated for 32 ohms rated impedance, is 97.6dB. That’s efficient enough that the P-IIs can deliver reasonably loud volume from mobile devices that have headphone jacks.

Bottom line: Except for some pretty wacky—but probably inconsequential—high-Q artifacts in the midrange frequency response, the Sivga P-II headphones measure fine.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 10 August 2021

Reviewed on: SoundStage! Solo, August 2021

I measured the Campfire Audio Satsuma earphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. For most measurements, the headphones were amplified using a Musical Fidelity V-CAN amplifier; I used a Schiit Magnius amplifier for distortion measurements. These are “flat” measurements; no diffuse-field nor free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

This chart shows the Satsumas’ frequency response. You could say this is similar to the historical norm for earphones, with the broad rise below about 800Hz, although the peaks centered at 3.2 and 7 are greater in magnitude and higher in Q (i.e., narrower) than usual. This suggests these earphones will sound bright.

This chart shows how the Satsumas’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop, some tube amps, or some professional headphone amps. There’s a big difference here, which is what I’d expect to see with single-driver balanced armature earphones. So the Satsumas’ sound will vary significantly depending on the impedance of the source device—when used with an amp that has a tube output stage, the sound will get even brighter.

This chart shows the Satsumas’ right-channel response compared two other Campfire Audio models: the dynamic-driver Honeydews and the Comets, which are earphones that the Satsumas are based on. You can see how close the Satsumas are to the Comets, and how much treblier they are than the Honeydews.

This chart shows the Satsumas’ right-channel response compared with models from other brands: the dynamic-driver Sennheiser IE 300s, the Shure Aonic5s (a triple balanced-armature design), and the AKG N5005s, which are said to be the earphones that come closest to the basic Harman curve target response for earphones. Although the AKGs have a lot more overall treble energy, it’s balanced out by the bass, so the Satsumas will sound brighter.

The Satsumas’ spectral decay plot looks very clean, with no significant resonances.

Total harmonic distortion of the Satsumas is a little on the high side relative to most earphones, but still, even at the extremely loud level of 100dBA (measured with pink noise), it doesn’t break 5% until you get below 80Hz, where harmonic distortion isn’t very audible, anyway.

In this chart, the external noise level is 85dB SPL, and numbers below that indicate attenuation of outside sounds. The lower the lines, the better the isolation. As you can see, the Satsumas, with their silicone tips, offer isolation that’s fairly typical for passive earphones. The Comets, on which the Satsumas are based, include foam tips, and they have some of the best passive isolation I’ve ever measured, so out of curiosity, I tried the Satsumas with some similar foam tips, and got isolation similar to what I measured from the Comets.

The Satsuma earphones’ impedance curve shows a huge swing from about 23 ohms at 20Hz to 350 ohms at 20kHz. The phase shift is likewise huge: +69 degrees above about 7kHz. This is why we see so much difference in frequency response with high- and low-impedance sources.

Sensitivity, measured between 300Hz and 3kHz, using a 1mW signal calculated for 46.4 ohms rated impedance, is 109.5dB. That’s very high, so the Satsumas should be able to deliver reasonably loud volume from any mobile device with a headphone jack.

Bottom line: The Satsuma earphones are clearly going to sound bright relative to typical earphones—and especially if you use them with a high-impedance source. Their treble will also have a bit different of a sound than that of most earphones, with specific and narrow emphasis in the lower and middle treble regions. But this is pretty much the way the Campfire Comets measured, and they were a very popular set of earphones among audiophiles.

. . . Brent Butterworth
brentb@soundstagenetwork.com

Details

Parent Category: Products

Category: Headphone Measurements

Created: 01 August 2021

Reviewed on: SoundStage! Solo, August 2021

I measured the Sony WF-1000XM4 earphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator with the RA0402 high-resolution ear simulator with KB5000/KB5001 simulated pinnae, and a Audiomatica Clio 12 QC audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. A Reiyin WT-04 USB Bluetooth transmitter was used to send signals from the Clio 12 QC to the earphones. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. Note that my usual impedance and sensitivity measurements are irrelevant for wireless earphones, and impossible to do without disassembling them, and are thus not included here. If you’d like to learn more about what our measurements mean, click here.

The above chart shows the WF-1000XM4s’ frequency response measured with the RA0402 ear simulator, with noise canceling off. It’s fairly normal except the midrange is more prominent than usual—or the bass and the lower treble peak between 2 and 4kHz are less prominent than usual.

Here we can compare the frequency response with noise canceling on and off. There’s almost no difference. As it should be.

This chart shows the WF-1000XM4s’ right-channel response (again, with noise canceling off) compared with other true wireless earphones: the KEF Mu3s (which are the true wireless earphones I’ve found come closest to the Harman curve), the Technics EAH-AZ70s, and the AKG N5005s, which are the passive earphones said to come closest to the Harman curve. You can see how much flatter the Sonys measure than the others, but in headphone measurements, flat is not the norm.

I had a lot of artifacts in my spectral-decay (waterfall) measurement, probably related to a Bluetooth artifact or noise, so I had to smooth it to 1/6th octave to be able to make sense of it. You can see some small resonances around 4 and 5kHz, but they are well-damped and gone within a few milliseconds.

The WF-1000XM4s’ distortion is very low at 90dBA (measured with pink noise), which is a pretty loud listening level. At 100dBA, the distortion gets very high, but at 98dBA (not shown), it’s only a little higher than at 90dBA. So if you turn the earphones and your source device all the way up, with material that has a lot of peaks close to 0dBFS, you might hear a few notes break up—but listening at such an extremely loud level is very unwise.

This chart shows the WF-1000XM4s’ isolation in Ambient Sound mode, and with noise canceling on and off. I compared these results with the KEF Mu3 earphones (which have lousy noise canceling) and the Technics EAH-AZ70s (which have excellent noise canceling). The Sonys don’t offer the best noise canceling I’ve seen in this product category, but they’re well above-average.

Latency with the WF-1000XM4s connected to the Reiyin WT-04 Bluetooth transmitter typically measures about 233ms. That’s decent for true wireless earphones, although you’ll do better if you can use aptX Adaptive or aptX Low Latency—and probably with LDAC, too, but I don’t have a Bluetooth transmitter that includes LDAC.

Bottom line: The Sony WF-1000XM4 earphones combine very good noise canceling with a frequency response that’s a bit midrange-heavy (or bass- and treble-light), but still well within the range of normal.

. . . Brent Butterworth
brentb@soundstagenetwork.com