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Parent Category: Products

Category: Headphone Measurements

Created: 20 January 2022

Reviewed on: SoundStage! Solo, January 2022

I measured the Soundcore Frames using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, an Audiomatica Clio 12 QC audio analyzer, and a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. I placed the Frames on the ear/cheek simulator in the same position they’d be in when used on an actual human ear. Note that because this product is physically much different from headphones or earphones, these measurements, for the most part, cannot be directly compared with our usual headphone measurements. In fact, due to the Bluetooth connection and the unusual configuration of the product, some of our usual measurements (including spectral decay and isolation) were impractical or pointless to perform. If you’d like to learn more about what our measurements mean, click here.

This chart shows the Frames’ frequency response, measured with pink noise. At first glance, this doesn’t look good. But after measuring the Frames’ response with two different real-time analyzers and with a sine sweep on the Clio 12 QC, and seeing similar results, it dawned on me that comparing this product’s frequency response with that of headphones or earphones does not reflect its performance, as the Frames do not interact with the pinnae in the same fashion. Acoustically, they work more like speakers, which is why . . .

. . . I decided to compare them with speakers, specifically a Revel Performa3 speaker (one of the flattest-measuring speakers you can buy) measured in-room at a distance of 2.5m—but using the GRAS 43AG instead of a measurement microphone. I also threw in a good set of earphones, the Meze Rai Pentas, for comparison. Now the Frames’ response doesn’t look so wacky. In fact, the Frames aren’t far off the Revels’ response, except that they don’t have any bass.

This looks different from our usual distortion chart because I couldn’t get the Clio 12 QC’s sine analyzer to track the Frames, perhaps due to the latency, or some other factor. Normally we do this measurement at 90dBA and 100dBA, but the Frames wouldn’t play that loud. Instead, I measured them at 80dBA and 75dBA. Not surprisingly considering the size of the drivers, distortion is fairly high in the bass, but I think you’d only notice it in the 200Hz range—lower than that, and the distortion harmonics are well outside the human ear’s range of maximum sensitivity, so the distortion doesn’t usually become audible until it tops about 10%. Above about 500Hz, distortion is actually pretty low.

Latency with the Frames averaged around 53ms when fed signals from a Reiyin WT-04 USB Bluetooth transmitter. That’s surprising, considering that the Frames include no low-latency Bluetooth codecs, only SBC and AAC.

One more note: I measured the Frames’ maximum volume using the same technique I use to measure max volume of kids’ headphones—with -10dBFS pink noise playing full-blast, measured in dBA. I got 86.3dBA, which is about what I typically measure from kids’ headphones that limit volume as they’re supposed to (many do not). So that means the Frames play loud enough for casual listening, but not loud enough for any kind of focused, attentive music listening.

Bottom line: I assume this is the first set of measurements published for Bluetooth glasses, so we have no paradigm by which to judge the Frames. However, they’re designed with what seems to be a theoretically appropriate response for a product like this; their glaring flaw is that the tiny speaker drivers don’t play very loud or low.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 10 January 2022

Reviewed on: SoundStage! Solo, January 2022

I measured the CCA C10 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. The headphones were amplified using a Musical Fidelity V-CAN amplifier. I used the supplied medium-sized 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 C10s’ frequency response. Nothing really remarkable here; it’s unlikely anyone would find the sound of these earphones idiosyncratic. I had worried that, given their very low price, we might see a significant mismatch in the response and sensitivity of the left and right earphones, but they match very well, never varying by more than about 1dB.

This chart shows how the C10s’ 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 balanced armatures, we see some significant differences, although in this case they’re not major—the high-impedance source produced about 1.5 to 3dB less output between 6 and 15kHz, which listeners will hear as a mild softening of the sound, but not as an unnatural coloration.

This chart shows the C10s’ right-channel response compared with various earphones, including the AKG N5005s, which are said to be the passive earphones that come closest to the Harman curve. The C10s are safely in the ballpark of “normal,” and in the mids and treble, they’re close to the Harman curve. They’re a little different in the bass, though, with 2 or 3dB more energy in the upper bass, between about 80 and 250Hz, and about 2 or 3dB less energy in the lower bass, below about 70Hz.

The C10s’ spectral-decay plot looks pretty clean, with no significant resonances in the mids and treble, and just a bit of bass resonance from the dynamic driver.

The C10s’ total harmonic distortion is pretty close to zip.

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. In the 43AG ear/cheek simulator, the C10s didn’t offer quite as much isolation as some similar models with over-ear cable routing, but they still did fine, and better than most earphones with conventional, “hang from the earphone” cable routing.

The C10s are a little unusual for earphones with balanced armatures. Normally with balanced armatures, we’d see a rise in impedance in the treble, but above about 5kHz, the impedance falls quite a bit, which is why we see the treble reduction with high-impedance sources. (The electrical phase swing is pretty mild, though.) Interestingly, the impedance is just about dead-flat up to a little over 1kHz, which leads me to guess that the dynamic driver is active up to at least 1kHz, maybe higher.

Sensitivity, measured between 300Hz and 3kHz, using a 1mW signal calculated for 32 ohms rated impedance, is 115.8dB, which means the C10s will deliver loud volume from any source device.

Bottom line: No red flags here, which is rather shocking considering the complexity and low price of this design.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 01 January 2022

Reviewed on: SoundStage! Solo, January 2022

I measured the Campfire Audio Holocene 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. The headphones were amplified using a Musical Fidelity V-CAN amplifier. I used the supplied medium-sized 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 Holocenes’ frequency response. It’s definitely idiosyncratic, especially for earphones—mainly in that it’s much flatter than we normally see. Instead of a rise in the bass response below about 200Hz, the bass gradually rolls off. Instead of a strong, octave-wide, 10dB-ish peak somewhere between 2 and 4kHz, there’s a two-octave-wide bump of just 2 to 4dB. The strongest response is in a peak centered at about 9.5kHz.

This chart shows how the Holocenes’ 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 expected with balanced armatures, which have very non-flat impedance curves, there’s a big difference in tonal balance with the high-impedance source—it gets a lot more trebly. So I wouldn’t use these earphones with, say, a tube amp, and if I used them in the studio, I’d only do so with a headphone amp that has an output impedance of 1 ohm or lower (sadly, though, the output impedance of headphone amps is rarely specified).

This chart shows the Holocenes’ right-channel response compared with the Campfire Mammoth and the AKG N5005 earphones, which are said to be the passive earphones that come closest to the Harman curve. You can see how idiosyncratic the Holocenes’ response looks, and how “normal” the Mammoths’ response looks.

This chart shows the Holocenes’ right-channel response compared again with the AKG N5005 earphones, plus the Meze Rai Pentas and the Audeze Euclids—two high-end earphones I like a lot. It’s easy to see how idiosyncratic the Holocenes’ response is. The only earphones I can recall that measure anything like the Holocenes are the Sennheiser IE 300 earphones, which I thought were pretty great for their price. Because I didn’t bring my lab computer with me on my holiday travels, I couldn’t include that measurement here, but you can see it by clicking here. As you’ll see, the IE 300s’ curve looks much like the Holocenes’ curve, but with a lot more bass.

The Holocenes’ spectral-decay plot looks clean, with no significant resonances.

The Holocenes’ total harmonic distortion is very low, especially for balanced armatures—it never rises to even 1%.

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. With the foam tips installed, the Holocenes deliver outstanding isolation, so good that I had to lower the floor of the chart from 40dB SPL to 30dB to show the curve. Even in the upper bass, where many earphones deliver little or no isolation, the Holocenes averaged about a 20dB noise reduction. If you’re on a plane, you’ll still hear some low-frequency rumble, but this is actually better isolation than most noise-canceling headphones offer—and without the boost in noise above 1kHz that many noise-canceling headphones suffer.

As usual with balanced armatures, the Holocenes show a big impedance swing—from 3 ohms in the bass up to about 18 ohms at 7.2kHz. The electrical phase shows a correspondingly large swing, which is why the Holocenes are sensitive to the output impedance of the source device. Stick to a low-impedance source device with these; I’d seek out something with 0.5-ohm output impedance or lower.

Sensitivity, measured between 300Hz and 3kHz, using a 1mW signal calculated for 5.4-ohms rated impedance, is 111.9dB. That’s very high, so the Holocenes will deliver loud volume from any source device.

Bottom line: I liked these earphones a lot, and I liked the somewhat similar-sounding, similar-measuring Sennheiser IE 300 earphones, too, so maybe this type of frequency response is a viable alternative to more typical earphone responses? Tough to say without a lot more research. Other than their idiosyncratic frequency response and their sensitivity to the output impedance of the source device (which is common with balanced armatures), the Holocene earphones appear to conform to standard engineering practice and show no technical flaws.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 20 December 2021

Reviewed on: SoundStage! Solo, December 2021

I measured the Monoprice Monolith AMT 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 AMTs’ frequency response. It’s definitely idiosyncratic. Had you shown me this curve and not told me what kind of product it is, I’d have guessed it’s a single-driver speaker with a whizzer cone, rather than headphones, because it’s essentially flat up to about 1.2kHz, gets a little ragged in the mids, and gets very hashy in the treble. With open-back headphones, we’d typically see a similarly flat response to about 1kHz, then a large peak, roughly +10dB centered somewhere between 2 and 4kHz. It’s the lack of this peak that causes the de-emphasis of vocals I heard in the AMTs.

Here we can see the difference in the headphones’ response when a high-impedance (75 ohms) source is substituted for a typical low-impedance source (5 ohms). As is almost always the case with ribbon drivers, there’s no difference because the load is almost purely resistive. So other than needing a lot of power (which we’ll discuss below), the AMTs will sound consistent no matter what source device you choose.

This chart shows the AMTs’ right-channel response compared with a couple of other open-back models (including the HEDD Audio HEDDphones, which also have AMT drivers) and the AKG K371 headphones, which are said to be very close to the Harman curve. It’s clear that the AMTs are far off the norm, with much less upper-mid and lower-treble energy—although they are fairly close to the Audeze LCD-X headphones, but the LCD-Xes are also somewhat idiosyncratic.

The AMTs’ right-channel spectral-decay plot looks messy. There’s a bit of upper-bass resonance, but an unusual and strong resonance peak at 1kHz. We also see the “hash” between 2 and 6kHz that’s typical of open-back headphones, especially planar-magnetics (which use a different type of ribbon driver)—and even some hash way down around 1kHz, where I can’t remember ever seeing it before. I associate this hash with spaciousness rather than a specific tonal coloration; perhaps the extra hash in the mids is what makes these headphones sound so spacious.

Here’s the THD vs. frequency chart, measured at 90dBA and 100dBA (both levels set with pink noise). There’s no audible distortion here—I’d guess that the few little bumps that you see in the curves are just external noise and vibration leaking through the driver.

In this chart, the external noise level is 85dB SPL (the red trace), and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. You can see that the AMTs’ isolation is typical for large, open-back headphones. I included the Monoprice Monolith M565C headphones so you can see how a closed-back design compares.

The impedance magnitude, rated at 32 ohms nominal, is as flat as I’ve ever seen, right on 30.5 ohms through the whole audioband. Electrical phase is similarly flat.

Sensitivity of the AMTs, calculated for 32 ohms impedance and averaged from 300Hz to 3kHz, is just 89.9dB—so you’d better have a pretty strong amp to drive these.

Bottom line: The frequency response and spectral-decay plots indicate that the AMTs are definitely going to have their own sonic vibe.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 10 December 2021

Reviewed on: SoundStage! Solo, December 2021

I measured the Apos Audio Caspian 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 Caspians’ frequency response. This isn’t far out of the ordinary; the only unusual thing I see is either the elevated upper bass/lower mids between 200 and 700Hz, or the dip in the mids at 1kHz—depending on how you look at it. There’s about a 2.5-octave-wide bump in the bass centered at about 50Hz; I’d expected to see this bump from my listening, but more around 100Hz, so I’m guessing I was thrown off by the elevated upper bass.

Here we can see the difference in the headphones’ response when a high-impedance (75 ohms) source is substituted for a typical low-impedance source (5 ohms). The high-impedance source bumps the bass up about 1dB, so with high-impedance sources (most tube amps, some cheap or older laptops, and some professional headphone amps), the Caspians will sound very slightly warmer.

This chart shows the Caspians’ right-channel response compared with a couple of other open-back models and the AKG K371 headphones, which are said to be very close to the Harman curve. Despite the designer’s disdain for the Harman curve, the Caspians aren’t far off it. The big difference is (again, depending on how you look at it) the elevated upper bass/lower mids or the dip at 1kHz. There’s also a couple dB less treble energy above 4kHz, relative to the 3kHz peak, in the Caspians versus the K371s.

The Caspians’ right-channel spectral-decay plot looks pretty good—there’s a bit of the super-high-Q “hash” we usually see with open-back models up in the 2kHz range, and perhaps a little more resonance around 200Hz than we normally see (and which corresponds with the elevated upper bass), but nothing really out of the ordinary.

Here’s the THD vs. frequency chart, measured at 90dBA and 100dBA (both levels set with pink noise). This looks clean—yes, at the extremely loud level of 100dBA, distortion hits about 6.5% in the bass, but at such low frequencies, it’d need to be about 10% to be audible.

In this chart, the external noise level is 85dB SPL (the red trace), and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. You can see that the Caspians are somewhat less open to outside sounds than most other open-back models. I included the AKG K371 headphones so you can see how a closed-back design compares.

The impedance magnitude, rated at 33 ohms nominal, runs about 33 ohms through most of the audio range, except for a resonant peak at about 65Hz, all of which is common for a dynamic driver. Electrical phase shift is pretty mild.

Sensitivity of the Caspians, calculated for 33 ohms impedance and averaged from 300Hz to 3kHz, is 103.6dB—much lower than the rated 116 (Apos Audio doesn’t specify the frequency on that), but plenty enough to get satisfying volume from pretty much any source device.

Bottom line: Other than that excess energy in the upper bass and lower mids—which is easy to EQ out—no red flags here.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 01 December 2021

Reviewed on: SoundStage! Solo, December 2021

I measured the Etymotic Evo 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. The headphones were amplified using a Musical Fidelity V-CAN amplifier. I used the supplied medium-sized double-flange 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 Evos’ frequency response. The basic shape of the curve looks pretty normal; what’s unusual is the amount of overall treble energy. What we see here is a large-magnitude, broadband peak covering about 2 1/2 octaves of the upper mids and lower treble; what we’d more commonly see is something like a lower-magnitude, octave-wide peak centered at about 2.5kHz, and another, smaller peak centered at about 5 or 6kHz. The good news is that the response is smooth overall, which is why I didn’t hear any colorations other than the trebly tonal-balance tilt.

This chart shows how the Evos’ 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 pretty big difference: a boost of 2 to 4dB below about 150Hz—although based on my listening notes, I expect I’d like the sound better that way.

This chart shows the Evos’ right-channel response compared with the Etymotic ER3SE (a single-driver design tuned for a fuller response than most Etymotic models), Campfire Satsuma (a single-driver balanced-armature design), and AKG N5005 earphones, which are said to be the passive earphones that come closest to the Harman curve. The Evos definitely have a lot more bass than the ER3SEs—but they also have a lot more treble energy than the other earphones. But if you brought the bass up about 2dB and the treble down about 3dB, you’d have a response pretty close to that of the Harmon curve—good news for those who like to EQ their earphones.

The Evos’ spectral-decay plot looks clean, although there seems to be a bit of resonance sneaking up from the bass region.

At extreme crank, the Evos show a little bit of distortion in the midrange, but still, it’s below 2%, and with transducers, that level of distortion is unlikely to be 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. It’s clear that the Evos don’t isolate as well as somewhat similar designs like the Shure Aonic 5 and Campfire Satsuma earphones, and I’m sure that’s because the long sound tubes don’t allow the earphones to nestle securely into the pinnae; the fact that the bodies of the earpieces fill so much of the ears is what gives other earphones of similar design such excellent isolation.

Normally with balanced armatures, we can expect to see a sharp rise in impedance above about 2kHz, but with the Evos, there’s instead a big upswing in the bass. This is why we see such a large change in frequency response when the earphones are used with high-impedance sources. Phase is pretty flat, though.

Sensitivity, measured between 300Hz and 3kHz, using a 1mW signal calculated for 47 ohms rated impedance, is 106.4dB. That’s pretty high, so you won’t have any problem getting loud volume from the Evos no matter what source device you use.

Bottom line: These are definitely going to be trebly sounding earphones, and they’re unlikely to offer the kind of isolation you can get with most other earphones using over-the-ear cable routing, but from a purely engineering standpoint, the measurements show nothing to be concerned about.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 20 November 2021

Reviewed on: SoundStage! Solo, November 2021

I measured the Beyerdynamic DT 900 Pro X 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 DT 900 Pro Xes’ frequency response. If you showed me this chart without knowing what brand the product is, I’d guess it was from HiFiMan—because it has that brand’s characteristic flat response below 1kHz, and lots of energy in the upper mids and lower treble, between 2 and 8kHz.

Here we can see the difference in the headphones’ response when a high-impedance (75 ohms) source is substituted for a typical low-impedance source (5 ohms). This is a significant shift in tonal balance—the high-impedance source bumps the bass up about 2dB and dials the treble down about 1dB, so with high-impedance sources (most tube amps, and some cheap or older laptops, and some professional headphone amps), the DT 900 Pro Xes will sound even warmer.

This chart shows the DT 900 Pro Xes’ right-channel response compared with a couple of other open-back models and the AKG K371s, which are said to be very close to the Harman curve. So the DT 900 Pro Xes could be said to be Harman curve headphones but with less bass, or very similar to the HiFiMan HE400se headphones, which are among the fuller-sounding HiFiMan models.

Here’s how the DT 900 Pro Xes compare with the closed-back DT 700 Pro X headphones, which I borrowed from another reviewer. The frequency response measures almost the same, although I found they sound a little more different than would appear to be the case.

The DT 900 Pro X headphones’ right-channel spectral-decay plot looks about as clean as they get—there’s essentially no resonance here. That fancy three-layer driver seems to work as advertised.

Here’s the THD vs. frequency chart, measured at 90dBA and 100dBA (both levels set with pink noise). It may look a little high in the bass, but keep in mind that all the distortion is in the bass; that the generally accepted rough guideline for audibility of subwoofer distortion is 10%, and the DT 900 Pro Xes hit that level only at 20Hz; and that this is at the unrealistically loud listening level of 100dBA.

In this chart, the external noise level is 85dB SPL (the red trace), and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. Like the Austrian Audio Hi-X65s, the DT 900 Pro Xes would most accurately be considered “semi-open back,” because they block a lot more high-frequency sound than models such as the HiFiMan HE400se headphones do.

The impedance magnitude, rated at 48 ohms nominal, bottoms out at 45 ohms and swings up to 115 ohms at 50Hz, which isn’t unexpected for a dynamic driver. Phase shift is surprisingly mild for such a big impedance swing, though.

Sensitivity of the DT 900 Pro Xes, calculated for 48 ohms impedance and averaged from 300Hz to 3kHz, is 103dB—better than the rated 100dB, and enough to get satisfying volume from most source devices.

Bottom line: The only red flag here is that the DT 900 Pro X headphones’ tonal balance may get too soft when they’re used with a high-impedance source—so I’d be cautious about recommending them for use with tube amps.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 10 November 2021

Reviewed on: SoundStage! Solo, November 2021

I measured the Shure Aonic 215 Gen 2 earphones using laboratory-grade equipment: a GRAS RA0402 ear simulator 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, and added the KB5000/KB5001 simulated pinnae with the full 43AG ear/cheek simulator. For reasons I wasn’t able to figure out, using my Reiyin WT-04 USB Bluetooth transmitter to send signals from the Clio 12 QC to the headphones resulted in frequency-response measurements with a sharp downturn above 5kHz, but using my Mpow BH259A Bluetooth transmitter worked fine. For wired measurements, the headphones were amplified using a Musical Fidelity V-CAN amplifier. 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.

In the discussion and chart legends below, I’ll refer to Aonic 215 earphones for the wired measurements, and Aonic 215 Gen 2 earphones for the Bluetooth measurements.

This chart shows the Aonic 215s’ frequency response with a wired connection. (The cable is not included, but a standard MMCX cable works, and I felt this was probably a more precise representation of what these earphones do than the rather troublesome Bluetooth tests I did.) This is a fairly standard-looking response for good-quality earphones. The one characteristic I’ll point out is the relative lack of energy between 5 and 10kHz, which suggests the Aonic 215s won’t sound as spacious and airy as earphones with stronger response in this octave.

Here we can see the difference in response between the Bluetooth connection and the wired connection. It’s almost a perfect match, suggesting that Shure doesn’t employ any sort of DSP or EQ in its wireless adapters. The only difference is a little less bass response with the Bluetooth connection, and I’ve sometimes seen this anomaly in other measurements with the Mpow BH259A, so I wouldn’t put much stock in that result.

This chart shows the right-channel response of the Aonic 215 Gen 2s (with the Bluetooth connection), compared with a couple of other true wireless models, and with the AKG N5005, which closely tracks the Harman curve. The most important characteristic is the Shures’ strong midbass, compared with the weaker midbass and stronger low bass of the AKG and KEF models. The Shure curve is rather old-school, and tends to result in somewhat bloated bass—although in my listening tests, something in the treble seemed to balanced that out psychoacoustically.

The Aonic 215s’ right-channel spectral-decay plot (measured with the wired connection) shows only one very high-Q resonance, at 4.8kHz, and while it lasts about 20ms, it’s at -40dB, so the low level and the very narrow bandwidth make it extremely unlikely that this resonance would be audible.

Here’s the THD vs. frequency chart, measured using the wired connection at 90dBA and 100dBA (both levels set with pink noise). Distortion’s too low to bother commenting on.

In this chart, the external noise level is 85dB SPL (the red trace), and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. Like most earphones of the “cable-over-ear” type, the Aonic 215 Gen 2s offer excellent passive isolation—but I threw in the Bose QC earbuds so you could see how a true wireless model with top-notch noise canceling compares.

With the Reiyin transmitter, latency was typically around 30ms—a very low result, but I’ve seen comparable results with a few other aptX-equipped headphones and earphones that don’t claim to have low latency, but do nonetheless. With the Mpow transmitter, using a standard SBC connection, latency was typically around 320ms, which is not uncommon for true wireless models when a low-latency technology is not used in the source device.

Bottom line: Nothing much to be concerned about here—the Aonic 215 Gen 2s measure just fine with Bluetooth or with a wired connection.

. . . Brent Butterworth
brentb@soundstagenetwork.com