I measured the Aventho Wireless headphones using a G.R.A.S. Model 43AG ear/cheek simulator/RA0402 ear simulator, a Clio 10 FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-CAN amp. On the Model 43AG, I used the original KB0065 simulated pinna for most measurements, as well as the new KB5000 pinna for certain measurements, as noted. For measurements using a Bluetooth connection, I used my Sony HWS-BTA2W Bluetooth transmitter to send signals from the Clio 10 FW to the headphones. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed.
The Aventho Wirelesses’ frequency response (shown here in wired mode; I was unable to get consistent measurements from the left and right channels in Bluetooth mode) is a little unusual. A typical headphone response might have a mild, broad boost in the bass between about 50 and 200Hz, with a strong, distinct response peak at around 2.5 or 3kHz, and a weaker peak or two between 5 and 10kHz. The Aventhos instead have a relatively narrow peak at 150Hz, building gradually to a softer peak at about 2.6kHz. I’ve measured few headphones with such a frequency response, so it’s hard for me to predict what these will sound like based on these measurements.
This chart shows the right-channel frequency responses of the Aventho Wirelesses, measured with wired and wireless Bluetooth connections. The Bluetooth connection seems to have a few dB more average output in the bass, as well as weaker output above about 7kHz. This suggests that the Aventhos will sound softer in Bluetooth mode, but the gating required to compensate for Bluetooth’s latency does introduce some uncertainty into this measurement.
This chart shows the Aventhos’ right-channel frequency response measured with the old KB0065 pinna I’ve used for years, and with G.R.A.S.’s new KB5000 pinna, which I’ll be switching to because it more accurately reflects the structure and pliability of the human ear. I include this mostly for future reference rather than as something you should draw conclusions from; I intend to show both measurements in every review until I completely switch to the new pinna later this year.
This chart shows the Aventhos’ measured right-channel frequency response compared with those of another set of on-ear headphones of similar size (the AKG N60 NC Wirelesses, with their noise canceling activated) and a well-known reference for affordable passive headphones (the over-ear NAD Viso HP50s). Clearly, the Aventhos’ response is flatter overall, with a much less prominent peak in the 3kHz range. However, the Beyerdynamics’ bass rolloff may counteract their reduced treble response to create a subjectively flat response.
The Aventho Wirelesses’ spectral-decay (waterfall) chart looks very clean, with no significant resonances above about 600Hz, and lower-than-average resonance in the bass frequencies.
The total harmonic distortion (THD) of the Aventho Wirelesses, measured in wired mode because Bluetooth’s latency prevents my audio analyzer from doing distortion measurements, is a little on the high side, although it’s unlikely to be audible at normal listening levels. At 90dBA, the THD rises to about 1% at 100Hz and 4% at 20kHz. At the extremely loud level of 100dBA, it’s about 3% at 100Hz and 10.5% at 20Hz. That probably would be audible, but 100dBA is so loud that your ears will be strained, anyway.
In this chart, the external noise level is 85dB SPL; the numbers below that indicate the attenuation of outside sounds. The isolation of the Aventho Wirelesses is pretty good for an on-ear model with no active noise canceling, and is comparable to that of the over-ear NAD Viso HP50s. You can see from the isolation traces for the AKG N60 NC Wirelesses and Bose QC35IIs that active noise canceling will improve isolation at frequencies below about 1kHz.
The Aventhos’ impedance magnitude is the same with their power on or off, and ranges between 33 and 39 ohms. The phase response is similarly flat.
The sensitivity of the Aventho Wirelesses in wired mode, measured between 300Hz and 3kHz with a 1mW signal calculated for 32 ohms impedance (my default for internally powered headphones of no specified impedance), is 106.1dB. The Beyerdynamic Aventhos should give you plenty of volume when plugged into an airplane seat’s headphone jack, even when the battery is low.
. . . Brent Butterworth
brentb@soundstagenetwork.com
I measured the PSB M4U 8s using a G.R.A.S. Model 43AG ear/cheek simulator and RA0402 ear simulator, a Clio 10 FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-CAN amp. On the Model 43AG I used the original G.R.A.S. KB0065 simulated pinna for most measurements, as well as the new KB5000 pinna for other measurements, as noted. For tests in Bluetooth mode, I used a Sony HWS-BTA2W Bluetooth transmitter to send signals from the Clio 10 FW to the headphones. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed.
The M4U 8s’ frequency response is pretty much in accordance with contemporary ideas of which headphone FR is most pleasing to most listeners: fairly close to the so-called “Harman curve.” The bass is shelved up below 120Hz, and there’s a somewhat larger-than-usual peak at 3.5kHz; normally, this peak might be centered at more like 2.5kHz, and it might be a few dB lower in magnitude. This is almost certainly why I found the treble a bit bright overall. Note that the left channel did not exhibit this effect; while it’s possible that the two channels measure differently (a common occurrence in active headphones, because the acoustics can be different due to the batteries being on only one side, etc.), this headphone’s response is tuned with digital signal processing (DSP), so I suspect that this may be a measurement anomaly. However, none of my attempts to reposition the earpiece on the ear/cheek simulator were able to match the peak in the right channel.
This chart shows the right-channel frequency response of the M4U 8s measured in some of their operating modes: wired passive, wired active, wired active with NC on, and wired Bluetooth with NC off. You can see that only the wired passive mode deviates greatly from the others, which is no surprise -- it bypasses the active circuitry and the DSP used to tune the other modes. Switching on NC seems to boost the bass by a couple dB, and the top and bottom look slightly rolled off in Bluetooth mode -- although Bluetooth’s latency can introduce measurement anomalies, so I’m not 100% confident in this measurement.
This chart shows the M4U 8s’ measured right-channel frequency response in wired mode with NC on, measured with the old KB0065 pinna (which I’ve used for years) and G.R.A.S.’s new KB5000 pinna, which I’ll eventually be switching to because it more accurately reflects the structure and pliability of the human ear. (I include this mostly for future reference rather than as something you should draw conclusions from; I intend to show both measurements in every review until I completely switch to the new pinna later this year.)
This chart shows the M4U 8s’ measured right-channel frequency response compared with those of three other NC headphones: the PSB M4U 2s, the Sony WH-1000X Mk.2s, and the Bose QC25s. The M4U 8s deviate from the norm in only one clear way -- they have less midrange response between about 150Hz and 1.8kHz. In my experience, this doesn’t mean the midrange will necessarily sound recessed, but it does make the treble peak more subjectively prominent, even if it’s not really higher relative to the 500Hz normalization point used for this graph.
This spectral decay (waterfall) chart shows the results in passive mode; the results in active mode are similar, but the latency introduced by the DSP prevented me from getting a chart comparable to those I typically publish. There’s a bit of resonance in the bass, but it’s along the lines of what I’ve measured from many other over-ear, closed-back headphones. There’s also a series extremely high-Q (i.e., narrow bandwidth), low-magnitude resonances in the treble that correspond with the M4U 8s’ measured response peaks; I see this effect in most of the open-back planar-magnetic headphones I measure, but rarely in closed-back dynamic designs. While the response peak is certainly audible, these resonances are narrow, and low enough in magnitude, that I doubt they’d be audible.
Because I had to measure the total harmonic distortion (THD) of the M4U 8s in passive mode, again because of latency problems, this measurement shows only the distortion of the driver. It’s very low, rising to just 1% at 20Hz even at extremely loud listening levels.
In this chart the external noise level is 85dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. (Note that I recently switched from measuring at a level of 75dB to 85dB; this doesn’t change the way the isolation curves look, but an 85dB level allows me to get better measurements of NC headphones, which demand a lower noise floor.) The isolation of the M4U 8s isn’t exceptional, but it does get down into the ballpark of some of the better NC headphones; Sony’s WH-1000X Mk.2s beat it by a hair, and the Bose QC35 IIs by a few dB more, though the Boses (which have the best NC performance I’ve measured from over-ear headphones) are clearly much better -- at the cost of the “eardrum suck” noted in the review.
The M4U 8s’ impedance magnitude in wired passive mode averages about 38 ohms, with a nearly flat phase response. The impedance in the wired active mode was above the Clio 10 FW’s 1500-ohm limit for impedance measurements.
The sensitivity of the M4U 8s, measured between 300Hz and 3kHz with a 1mW signal calculated for the specified 32 ohms impedance, is 108.2dB in wired passive mode, or 110.8dB in wired active mode with NC on. The M4U 8s should deliver ample volume from any source device.
. . . Brent Butterworth
brentb@soundstagenetwork.com
I measured the Massdrop x NuForce EDC3 in-ear headphones using a G.R.A.S. Model 43AG ear/cheek simulator (including the RA0402 high-resolution ear simulator), a Clio 10 FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-CAN amplifier. On the Model 43AG, I used the original KB0065 simulated pinna for most measurements as well as the new KB5000 pinna for certain measurements, as noted. These measurements used the medium-sized silicone eartips; for isolation measurements, I tried both the silicone tips and the largest of the included foam tips. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed.
I can’t recall measuring a set of earphones with a response like that of the EDC3s. It looks more like the response of a set of large, open-back, planar-magnetic headphones: essentially flat up to about 1kHz, then rising to a broad peak between 1.4 and 3.2kHz, then to a couple of smaller peaks between 4 and 10kHz. That’s not necessarily to say that the EDC3s will sound like big planar-magnetic headphones -- they’re inserted into the ear canals, and thus bypass the acoustical effects of the pinna and the outer portion of the ear canal, which of course affect the sound quality of over-ear headphones.
This chart shows the EDC3s’ right-channel frequency response measured using only the RA0402 coupler (which has a stainless-steel tube into which an earphone fits), and measured using the Model 43AG ear/cheek simulator with G.R.A.S.’s new KB5000 pinna (which I’ll eventually switch to for my earphone measurements because it’s a more realistic representation of the acoustical environment presented by the human ear). I include this for future reference; I intend to show both measurements until I begin using only the new pinna.
This chart shows the results of adding 70 ohms output impedance to the V-CAN’s 5-ohm output impedance, to simulate the effects of using a typical low-quality headphone amp. As with every set of balanced-armature earphones I’ve measured, the EDC3s’ large swings in impedance (see impedance graph below) interact with the output impedance of the source device to change the response. Here, however, the effect is more subtle than I usually see -- you’ll get just a little less bass and a little more treble if you use a lower-quality headphone amp with a relatively high output impedance.
This chart compares the EDC3s’ measured right-channel frequency response with that of three other multidriver earphones: the 1More Quad Drivers, the PSB M4U 4s, and the Shure SE215s. Note how, compared with the EDC3s, all three competitors exhibit a large bump in the bass and a higher, more pronounced peak in the lower treble.
The ECD3s’ spectral-decay (waterfall) chart shows very low resonance overall.
The ECD3s’ total harmonic distortion (THD) is pretty low, and a bit unusual. At the testing levels I use (both are high relative to normal listening levels), there seems to be a flat 1% THD below 1kHz -- yet even at the very high testing level of 100dBA, the distortion doesn’t significantly rise. THD of 1% is common in transducers and generally not noticeable, but this test provides yet another indication that something a bit different is going on in the EDC3s.
In this chart, the external noise level is 85dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. (Note that I recently switched to measuring at a level of 85dB instead of 75dB; this doesn’t change the way the isolation curves look, but an 85dB level lets me get better measurements of noise-canceling headphones, which demand a lower noise floor.) The EDC3s deliver excellent isolation, especially when their included foam eartips are used. Even by the generally high standards of earphones with over-ear cable routing, this is an excellent result.
The EDC3s’ impedance, like that of all the balanced-armature earphones I can remember measuring, has a large swing, rising from 16 ohms in the bass to 53 ohms in the treble. The phase shift, too, is considerable, going from 0° in the bass to +72° at 20kHz. This is the reason for the change in sound quality when you switch from a low-impedance source (such as an iPhone or a typical good headphone amp) to a high-impedance source (e.g., the headphone amps built into most cheap laptops).
The sensitivity of the Massdrop x NuForce EDC3s, measured between 300Hz and 3kHz with a 1mW signal at their specified impedance of 20 ohms, is 109.1dB. This means that you should get plenty of volume from any source device.
. . . Brent Butterworth
brentb@soundstagenetwork.com
I measured the effects of Sonarworks’ True-Fi processing using a G.R.A.S. Model 43AG ear/cheek simulator (including the RA040X high-resolution ear simulator and KB5000 pinna), a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-CAN amplifier. Because the test files had to be processed through the Sonarworks app, I had to play a pink-noise file as the stimulus and use TrueRTA, instead of generating and analyzing signals using my usual Audiomatica Clio 10 FW analyzer. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed.
This chart shows the frequency response of the Audeze LCD-X headphones measured with and without True-Fi processing. True-Fi introduces a bass boost of about 7dB centered at 35Hz, and a treble boost of about 5dB maximum and centered at 3kHz, as well as a 4dB boost centered at 7.5kHz.
This chart shows the frequency response of the Bose QC20 earphones with noise canceling on, measured with and without True-Fi processing. True-Fi cuts the bass by about 7dB centered at 40Hz, and introduces treble cuts of about 4dB maximum centered at 3.1kHz, and 9dB centered at 8kHz.
This chart shows the frequency response of the Sony MDR-7506 headphones, measured with and without True-Fi processing. Here the effect is more subtle than with the above headphones and earphones. True-Fi cuts the bass by about 2dB centered at 60Hz, boosts the lower mids by about 4dB centered at 200Hz, and reduces the treble response by about 2dB on average between 4 and 7kHz.
Here you can compare the responses of the Audeze LCD-4, Sony MDR-7506, and Status Audio CB-1 headphones after True-Fi processing. It seems the target response is different for each design; if it were the same, the traces would overlap except for a few spurious variances caused by differences in the physical design of the headphones and the fit of their earpieces on the ear/cheek simulator.
In this chart you can see the effects of True-Fi’s Adjust for Age feature, with the intensity set to 50%, and the correction set for 55-year-old males and females and a 35-year-old man. Interestingly, this control introduces not only a treble rolloff, but also some effects on the bass and on the overall listening level.
What constitutes a “correct” measurement for the results above is very much a matter of debate, but these measurements do indicate that True-Fi’s corrections are not (at least in the cases of these headphone models) extreme or unexpected, and that Sonarworks does seem to have put some serious thought and work into each of the correction curves, rather than merely making each headphone model conform to the same curve.
. . . Brent Butterworth
brentb@soundstagenetwork.com
I measured the Bowers & Wilkins PXes using a G.R.A.S. Model 43AG ear/cheek simulator/RA0402 ear simulator, a Clio 10 FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-CAN amp. On the Model 43AG, I used the original KB0065 simulated pinna for most measurements as well as the new KB5000 pinna for certain measurements, as noted. Because I was unable to get the PXes to connect to my Sony HWS-BTA2W Bluetooth transmitter to send signals from the Clio 10 FW to the headphones, I had to use a wired connection; I couldn’t test with Bluetooth signals. However, this shouldn’t matter -- these headphones work only when powered on, so their internal amplifier (and, presumably, digital signal processing) are in the signal chain just as they would be when the headphones are fed a Bluetooth signal. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed.
The PXes’ frequency response looks pretty standard, with a mild boost in the bass and a strong peak centered at about 2.4kHz. This curve aligns with what is generally considered to be the proper curve for making headphones sound more like real speakers in a real room. Note that this is the best match I was able to get between the left and right channels in about a dozen attempts; note also that the narrow earpads made positioning the earpieces on the ear/cheek simulator far fussier -- the pads leave less margin for error in positioning. Not shown here is the result with a 75-ohm source impedance, which mimics the electrical effect of using the cheap headphone amp built into typical PC laptops and inexpensive MP3 players; because of these headphones’ high input impedance, using a higher-impedance source has almost no effect on frequency response.
This chart shows the right-channel frequency response of the PXes measured with noise canceling (NC) off, and with NC in the default settings of the three NC modes: Office, City, and Flight. (Adjusting the NC to the full Amplified setting did not affect frequency response.) The frequency response in Office mode is practically the same as with NC off, but clearly, the City and Flight modes will make these headphones sound substantially different.
This chart shows the PXes’ measured right-channel frequency response (NC off), measured with the old KB0065 pinna (which I’ve used for years) and with G.R.A.S.’s new KB5000 pinna, which I’ll be switching to because it more accurately reflects the structure and pliability of the human ear. (I include this mostly for future reference rather than as something you should draw conclusions from; I intend to show both measurements in every review until later this year, when I start using only the new pinna.) The difference here is far greater than I usually see, because it was so difficult to get the PXes consistently well seated on the ear/cheek simulator. This was the closest match I could get in more than a dozen tries.
This chart shows the PXes’ measured right-channel frequency response compared with three other NC headphone models: the Bose QC35 II, the PSB M4U 2 (generally considered to rank among the best-sounding NC headphones), and the Sennheiser HD 4.50 BTNC. You can see that the PXes’ response differs considerably from the others; it’s more of what’s often called a smiley-face curve, with pronounced bass and treble and a dip in the midrange.
The spectral-decay (waterfall) chart has an artifact I’ve never seen -- an apparent “echo” at about 6ms at frequencies below 1kHz. I don’t know what to make of it, but it showed up in repeated measurement attempts. The result shown is with NC off; activating the Flight NC mode somewhat reduced the artifact. Otherwise, this waterfall plot looks reasonably clean. The only resonance above 1kHz that lingers past 10ms is the one at 2kHz, which corresponds with the distortion peak seen below; still, it’s down about 40dB and so should be only negligibly audible.
The PXes’ total harmonic distortion (THD) is generally low except for the peak at 2kHz, which corresponds with the resonance shown in the waterfall plot. Note that switching NC on increases distortion, although it’s measurable only at what would be an extremely loud listening level.
In this chart, the external noise level is 85dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. (Note that I recently switched to measuring at a level of 85dB instead of 75dB; this doesn’t change the way the isolation curves look, but an 85dB level lets me get better measurements of NC headphones, which demand a lower noise floor.) The PXes’ isolation, shown here in Flight mode at the default setting, is perhaps a little above average for an over-ear NC model, and somewhere between the class-leading Bose QC35 II headphones and the more average PSB M4U 2 headphones in the critical “airplane cabin noise band” of 50-1200Hz.
This chart shows the isolation of the PXes in their various NC modes. Office mode provides a mild amount of NC, comparable to that of typical cheap NC headphones. City and Flight modes offer far stronger and more useful NC, although City mode passes along much more sound between 800Hz and 5kHz, presumably to allow the wearer to hear voices and approaching vehicles. The chart also shows the effect of pushing the NC-level adjustment to the maximum Amplified setting in Flight mode, which appears simply to reduce the level of NC.
The PXes’ impedance magnitude is very high at an average of 910 ohms, which is to be expected, considering that the headphones can’t be used in passive mode with the power off. This means that the input impedance you see is that of the internal drive electronics rather than of the headphone driver. It also means that, in wired mode, the sound will not vary significantly depending on the source device, because the headphones’ impedance will dominate the circuit. Phase shift is negligible, as is to be expected from the nearly flat impedance.
The sensitivity of the PXes in wired mode with NC off, measured between 300Hz and 3kHz with a 1mW signal and calculated for the specified 22 ohms impedance in wired mode, is 105.3dB. You should have no problem getting adequate volume when you plug the Bowers & Wilkins PXes into an airplane seat’s headphone jack.
. . . Brent Butterworth
brentb@soundstagenetwork.com
I measured the Heritage HP-3s using a G.R.A.S. Model 43AG ear/cheek simulator (including the RA040X high-resolution ear simulator), a Clio 10 FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and Musical Fidelity V-CAN and Audio-gd NFB1-AMP headphone amplifiers. On the G.R.A.S. 43AG I used the original KB0065 simulated pinna for most measurements, as well as the new KB5000 pinna for some measurements, as noted. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed.
The HP-3s’ frequency response is well within the norm for what researchers generally consider the most appropriate and realistic-sounding response curve for headphones. However, their bass response is quite different from that of most open-back audiophile headphones, which are often more or less flat up to about 1kHz.
This chart shows the HP-3s’ right-channel frequency response, measured with the old KB0065 pinna I’ve used for years and with G.R.A.S.’s new KB5000 pinna, which I’ll be switching to because it more accurately reflects the structure and pliability of the human ear. I include this mostly for future reference, rather than as something you should draw conclusions from; I intend to show both measurements until I begin using only the new pinna, probably sometime this spring.
This chart shows the results of adding 70 ohms output impedance to the V-CAN’s 5-ohm output impedance to simulate the effects of using a typical low-quality headphone amp. There’s effectively no difference in response, which means the headphones’ tonal balance shouldn’t change when you switch from driving them with a good headphone amp to driving them with a cheap laptop.
This chart shows the HP-3s’ measured right-channel frequency response compared with the Audeze LCD-X open-back planar-magnetic headphones and the Focal Clear dynamic open-back headphones. The HP-3s, despite their measured midrange dip, actually appear to be closer to what’s typically considered the most appropriate response curve for headphones, though they certainly produce more bass than most large, open-back audiophile headphones.
The spectral decay (waterfall) chart shows very low resonance overall, particularly in the bass, where most headphones are nowhere near as well controlled. There’s a resonance centered at 1.8kHz, but it’s down about 40dB, and its Q is so high (i.e., its resonance bandwidth is so narrow) that I can’t imagine it would be audible.
The HP-3s’ total harmonic distortion is a hair on the high side compared with the THD of large planar-magnetic headphones, but it’s typical for large dynamics, and in fact is similar to what I measured from the Focal Clear dynamic headphones. THD is negligible above 100Hz, but rises to 2.7% at 20Hz at 90dBA, which is a very loud listening level. The THD rises to 8.2% at 20Hz at the even louder level of 100dBA, but that’s extremely loud -- I’d never listen at that level for more than a second or two.
In this chart, the external noise level is 85dB SPL; the numbers below that indicate the attenuation of outside sounds. (Note that I recently switched to measuring at a level of 85dB instead of 75dB; this doesn’t change the way the isolation curves look, but an 85dB level allows me to get better measurements of noise-canceling headphones, which demand a lower noise floor.) This is an impressive result for semi-open-back headphones. The HP-3s deliver far better isolation than open-back models; their isolation curve looks more like that of large, closed-back models such as the Audeze LCD-XC than like that of an open-back model.
The HP-3s’ impedance magnitude stays mostly around the specified 25 ohms, with a slight bump to 28 ohms centered at 55Hz. Phase shift is negligible. This basically flat, relatively low impedance plays a big part in making the HP-3s sound good with smartphones.
The sensitivity of the HP-3s, measured between 300Hz and 3kHz with a 1mW signal at the specified 25 ohms impedance, is 97.1dB. This sensitivity, relatively high for a large audiophile headphone, means you should get a comfortable listening level from practically any source device.
. . . Brent Butterworth
brentb@soundstagenetwork.com
I measured the Focal Clears using a G.R.A.S. Model 43AG ear/cheek simulator (including the RA040X high-resolution ear simulator), a Clio 10 FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and Musical Fidelity V-CAN and Audio-gd NFB1-AMP amplifiers. On the Model 43AG I used the original KB0065 simulated pinna for most measurements, as well as the new KB5000 pinna for certain measurements, as noted. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed.
The Clears’ frequency response is not far outside the norm for open-back headphones, with a few anomalies worth noting. First, these headphones have a strong response peak centered at about 1.5kHz; with most headphones, this peak is somewhere between 2 and 3kHz, and is generally thought to make headphones sound more like loudspeakers in a room. Second, some small wrinkles in the response curves between 1.3 and 3.3kHz correspond with the resonances I note below. (This is an unsmoothed measurement; smoothing to 1/12 octave, which many technicians do when measuring headphones, conceals these tiny anomalies.) Third, the left and right earpieces don’t match very well between 1.7 and 4kHz. Channel mismatches are common due to the differences between the left and right simulated pinnae, and because it’s practically impossible to get precisely the same fit every time you place a headphone on the ear/cheek simulator, but this was a larger mismatch than I usually see -- and a more consistent one, as I confirmed by measuring each earpiece six times.
This chart shows the Clears’ measured right-channel frequency response measured with the old KB0065 pinna (which I’ve used for years) and G.R.A.S.’s new KB5000 pinna, which I’ll be switching to because it more accurately reflects the structure and pliability of the human ear. (I include this more for future reference than as something you should draw conclusions from; I intend to show both measurements until I completely switch to the new pinna, probably sometime this spring.)
This chart shows the results of adding 70 ohms output impedance to the V-CAN’s 5-ohm output impedance, to simulate the effects of using a typical low-quality headphone amp. Obviously, there’s a large difference, due to the big impedance swing in the bass (see below) -- the Clears will sound a lot bassier, and probably duller, if plugged into a headphone amp with high output impedance, such as some of those built into laptop computers as well as some professional amps. I recommend using a good-quality amp with a low output impedance, preferably under 5 ohms.
This chart shows the Clears’ measured right-channel frequency response compared with the responses of the Audeze LCD-X and Oppo Digital PM-1 open-back planar-magnetic headphones and Sennheiser’s HD 800 S dynamic open-back model. The Clears had somewhat less response above 4kHz than the other three, and stronger response between 800Hz and 2kHz, which perhaps explains my perception of hearing more midrange detail with the Clears.
The spectral decay (waterfall) chart shows many very high-Q (narrow), low-magnitude resonances between 1.3 and 7kHz. This is something I often see with open-back models, even some of the most highly regarded headphones on the market. (When I do this measurement, I cover the back of the headphone with 4” of denim insulation so that the measurement doesn’t include environmental noise, or echoes of the sound leaking from the earpiece’s open back.)
The Clears’ total harmonic distortion (THD) was generally low, rising to 1.3% at 20Hz at 90dBA, a very loud listening level. At 100dBA, the THD did rise below 30Hz, to 8.8% at 20Hz, but considering that 100dBA is extremely loud and that music has almost no content below 30Hz, this shouldn’t be significant.
In this chart, the external noise level is 85dB SPL; the numbers below that indicate the level of attenuation of exterior sounds. (Note that I recently switched to measuring at a level of 85dB instead of 75dB; this doesn’t change the way the isolation curves look, but 85dB lets me get more accurate measurements of noise-canceling headphones, which demand a lower noise floor.) Like other open-back models, the Clears offer negligible isolation; I include the closed-back Audeze LCD-XC ’phones to illustrate the isolation of a similarly constructed closed-back model.
The Clears’ impedance magnitude ran higher than its specified 55 ohms, averaging about 70 ohms above 200Hz and rising to a peak of 420 ohms (the driver’s resonance) at 42Hz. Phase shift is a little on the high side, running +/-25% from 250Hz to 20kHz, with a bigger swing in the bass that corresponds with the driver resonance.
The sensitivity of the Clears, measured between 300Hz and 3kHz with a 1mW signal at the specified 55 ohms impedance, was 101.6dB. You should be able to get adequate listening volume from practically any portable device, although, as my other measurements show, the tonal balance may tilt in a way that doesn’t sound great.
. . . Brent Butterworth
brentb@soundstagenetwork.com
Reviewed on: SoundStage! Solo, October 2018
I measured the Anandas using a G.R.A.S. Model 43AG ear/cheek simulator/RA0402 ear simulator, a Clio 10 FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-CAN amp, with an Audio-gd NFB-1AMP used for distortion measurements. On the Model 43AG, I used the new KB5000 and KB5001 anthropomorphic simulated pinnae for most measurements, and the original KB0065 pinna for certain other measurements as noted. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed.
The above chart shows the Anandas’ frequency response measured with the new KB5000 and KB5001 anthropomorphic simulated pinnae. This is a fairly typical response for large, open-back planar-magnetic headphones. While the response is flatter than I measure in most headphones, this doesn’t necessarily translate to a flat perceived response.
This chart shows the Anandas’ right-channel frequency response measured with the old KB0065 pinna (which I’ve used for years) and the new KB5000 pinna, which I recently switched to because it more accurately reflects the structure and pliability of the human ear. This is just for sake of comparison with older measurements of mine.
Here you can see how the Anandas’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop or some cheap professional headphone amps. As with all the planar-magnetic headphones I can remember measuring, the output impedance of the source device has no audible effect on the tonal balance of the headphones.
This chart shows the Anandas’ right-channel response compared with two other high-end closed-back headphones (the Acoustic Research AR-H1s and Audeze LCD-Xes), as well as the Sony MDR-7506es, a standard fixture in audio production work that generally conform to the “Harman curve,” shown in research by Harman International to be the preferred over-ear headphone response for most listeners. These measurements use the older KB0065 pinna, because that’s the only measurement I have for the LCD-Xes. Clearly, the Anandas’ response is flatter than average, but in this measurement, that suggests that the sound may be somewhat midrange-focused.
The Anandas’ spectral decay (waterfall) chart shows the very-low-level midrange hash I often see with open-back planar-magnetic headphones, but after about 3 milliseconds, most of it’s down to -40dB, so I don’t see this as a problem -- especially since I generally like the sound of this headphone type. The bass resonance is nearly non-existent.
As usual with planar-magnetic headphones, the measured total harmonic distortion (THD) of the Anandas is almost non-existent even at very loud levels. Note that I’ve increased the resolution of this chart by reducing the range from 50% THD to 20%, which makes the Anandas’ distortion look higher relative to previous charts I’ve published. I initially chose 50% as my range many years ago, when I was measuring a lot of cheap, mass-market headphones, but few of the headphones I review now exceed 10% distortion.
In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The Anandas’ isolation is near zero, although for open-back headphones that may be a good thing, because it shows that the grille behind the driver offers very low acoustical impedance.
The Anandas’ impedance response is not quite as dead-flat as I’m used to seeing with open-back planar-magnetics; there are little bumps at 70 and 120Hz. However, these are far too small to affect the headphones’ performance. Electrical phase is almost perfectly flat.
Sensitivity of the Anandas, measured between 300Hz and 3kHz using a 1mW signal calculated for 25 ohms impedance, is 92.5dB. Although it should deliver a useable volume with most source devices, it won’t achieve natural dynamics and volume unless it’s used with a high-quality portable music player or an external amp.
. . . Brent Butterworth
brentb@soundstagenetwork.com
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