I measured the RBH Sound EP3s using a G.R.A.S. Model RA0045 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 headphone amplifier. I primarily used one of the smaller Comply foam eartips supplied with the EP3s because it fit the simulator well, and I figure it’s what most listeners will prefer. For comparison, I also include a measurement taken with one of the supplied silicone tips. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.
This is the frequency response of the EP3s using the smaller of the supplied Comply foam eartips. There’s a little more bass and treble output (or a little less midrange output) than I’m used to seeing.
This chart shows the EP3s’ frequency response with the Comply foam tip (green trace) and the medium-size silicone tip (purple trace). The slight difference is perhaps enough to cause the EP3s to sound slightly brighter with the silicone tip. Because the shapes and sizes of ear canals vary, so may the actual results you get with these tips.
Adding 70 ohms output impedance to the V-Can’s 5 ohms to simulate the effects of using a typical low-quality headphone amp has zero audible effect on the sound of the EP3s.
You can see from this chart that the EP3s (blue trace) have stronger bass and treble output than RBH’s EP1s (red trace), and that both have much less midrange energy than the PSB M4U 4s (green trace). The Sennheiser IE 800s -- which I included because they’re well-regarded earphones that also have ceramic enclosures -- have much less lower-treble response, but a stronger 10kHz response than any of the other headphones measured here.
Resonance in the EP3s is mild and well damped, other than the bass resonances that have shown up in almost every set of earphones I’ve measured.
The EP3s’ total harmonic distortion (THD) is low. At the loud listening level of 90dBA, the distortion will almost certainly be inaudible. A narrow THD peak at 2.7kHz rises to about 3.5% at 100dBA, but it’s probably not troublesome, considering that: 100dBA is way louder than most people would ever listen; the peak is narrow; and the first three distortion products will be at the high frequencies of 5.4, 8.1, and 10.8kHz.
In this chart, the external noise level is 75dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. The EP3s’ isolation is fantastic with the supplied eartips of Comply (shown) or silicone (not shown, but almost exactly the same result). They reduce ambient noise in the “jet-engine band” of 100-200Hz by 17-20dB -- better, even, than most noise-canceling headphones can achieve.
The EP3s’ impedance magnitude is essentially flat at 16 ohms, as is the phase.
The sensitivity of the EP3s, measured between 300Hz and 3kHz with a 1mW signal calculated for the rated 16 ohms impedance, is 105.2dB, which is above average; the EP3s should play quite loudly, regardless of the source device used.
. . . Brent Butterworth
brentb@soundstagenetwork.com
I measured the Viso HP30s using a G.R.A.S. Model 43AG ear/cheek 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 headphone amplifier. I used the clamping mechanism on the ear/cheek simulator to ensure a good seal (as I always do with on-ear models), and moved the headphone around to several different locations on the simulator plate to find the one with the most bass and the best average of midrange and treble responses. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.
This chart shows the HP30s’ frequency response, which is fairly flat. There’s a mild dip in the midrange, which I believe has something to do with the RoomFeel voicing (and anyway isn’t uncommon in headphones), plus a broad, relatively mild peak centered at 3.5kHz. In most of the headphones I measure, this peak -- which is intended to make headphones sound more like speakers in a room -- is narrower, higher in magnitude, and a little lower in frequency.
Adding 70 ohms of output impedance to the V-Can’s 5 ohms to simulate the effects of using a typical low-quality headphone amp shows a broad boost below 80Hz that maxes out at +1.5dB. It might barely be audible, but certainly wouldn’t be objectionable.
This chart compares the HP30s (blue trace) with NAD’s Viso HP50 over-ear (red) and Beyerdyamic’s T 51 p (green) and Bowers & Wilkins’ P3 (orange) on-ear models. These curves are normalized to 500Hz, which is near where the HP30s’ response is weakest; while it looks as if the HP30s have a lot more bass and treble than the others, they’re actually fairly close to what I measured from the HP50s.
The HP30s’ waterfall plot shows less bass resonance than usual (not so surprising, considering there’s not much enclosure to resonate), and only a few extremely narrow and almost certainly inaudible resonances at a few higher frequencies.
The measured total harmonic distortion (THD) of the HP30s is a little on the high side in the bass, although I didn’t notice it in my listening tests. (I could, however, hear the distortion when I cranked up Mötley Crüe’s “Kickstart My Heart” to a level louder than I’d ordinarily listen.) The THD is about 2% at 100Hz, measured at the high listening level of 90dBA measured with pink noise. At the extremely high level of 100dBA, which I use only for measurement purposes, it hits 3% at 100Hz, rising to 11% at 20kHz.
In this chart, the external noise level is 75dB SPL; the numbers below that indicate the level of attenuation of outside sounds. The HP30s don’t offer much isolation, but few passive on-ear models do. There’s little or no attenuation below 600Hz, and attenuation of only 5 to 7dB from 600Hz to 2kHz. The HP30s wouldn’t be a good choice for air travel.
The HP30s’ impedance magnitude is fairly flat, running at or near the specified 32 ohms, except for a peak at 37 ohms right around 50Hz. The impedance phase is also mostly flat.
The sensitivity of the HP30s, measured between 300Hz and 3kHz with a 1mW signal calculated for the specified 32-ohm impedance, averages 109.2dB, which means they’ll play loud from any source device.
. . . Brent Butterworth
brentb@soundstagenetwork.com
I measured the HiFiMan HE1000s using a G.R.A.S. Model 43AG ear/cheek 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 headphone amplifier. I moved the headphones around to several different locations on the ear/cheek simulator to find the one that produced the most bass and the most characteristic response. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.
This chart shows the HE1000s’ frequency response, which is flat up to 1.5kHz, and rises sharply above that from 2 to 9kHz.
Adding 70 ohms output impedance to the V-Can’s 5 ohms to simulate the effects of using a typical low-quality headphone amp has no audible effect on the HE1000s’ frequency response.
This chart compares the HE1000s (blue trace) with HiFiMan’s HE560s (red trace) and Audeze’s LCD-3s (green trace). The HE1000s have a similar response to the HE560s, with about 5dB more energy between 5 and 9kHz, and a little more bass to help balance out that treble peak. The LCD-3s have much less treble energy above 2.5kHz, and a flatter measured response, than either HiFiMan model. Note that, unlike with most speakers, a flat measured response in headphones does not necessarily equate with a flat perceived response.
The HE1000s’ waterfall plot may not look very clean at first glance, but if you look close you’ll see that all those little blue streaks are resonances of very narrow bandwidth about -40dB below the test signal. The only resonance shown here that might be audible is the combination of two adjacent -20dB resonances near 5kHz.
The total harmonic distortion (THD) of the HE1000s is well below audible levels, even at the extremely high level of 100dBA, measured with pink noise.
In this chart, the external noise level is 75dB SPL; the numbers below that indicate attenuation of outside sounds. As is almost always the case with open-back headphones, the HiFiMan HE1000s provide essentially no noise isolation; any sounds from outside them will come right through.
The impedance magnitude of the HE1000s is nearly dead flat at 37 ohms; the impedance phase, too, is nearly flat.
The sensitivity of the HE1000s, measured between 300Hz and 3kHz with a 1mW signal calculated for the specified impedance of 35 ohms, is 88.1dB. Although that’s relatively low, as I say in the review, it was enough for me to get a fairly comfortable volume level from my smartphone.
. . . Brent Butterworth
brentb@soundstagenetwork.com
I measured the NightHawks using a G.R.A.S. Model 43AG ear/cheek 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 headphone amplifier. I moved the NightHawk earpiece around to several different locations on the ear/cheek simulator to find the position that gave the most bass and the best average of midrange and treble responses. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.
This chart shows the NightHawks’ frequency response, which is most notable for being fairly flat, with little to none of the usual peak between 2 and 4kHz. There’s a dip centered at 1.2kHz, and a gradual bass rolloff.
Adding 70 ohms of output impedance to the V-Can’s 5 ohms to simulate the effects of using a typical low-quality headphone amp has no audible effect on the NightHawks’ frequency response.
This chart compares the NightHawks (blue trace) with the Oppo Digital PM-3s (red trace) and the NAD Viso HP50s (green trace); both of the latter have received generally positive reviews. The NightHawks are clearly very different, with a more resonant (less flat) bass response and about 10dB less treble energy on average.
The NightHawks’ waterfall plot looks clean, with no major resonances, and very low resonance in the bass frequencies compared with most over-ear headphones I’ve measured.
The total harmonic distortion (THD) of the NightHawks is, as claimed by AQ, very low, even at the extremely high level of 100dBA, measured with pink noise. Even at 10Hz/100dB, there is only 1% THD. Note that because of the AQs’ semi-open-back design and the fact that I measure distortion in a very quiet room but not in an anechoic chamber, even the slight distortion seen in this chart may be mostly noise leaking in. (To improve the signal/noise ratio of this measurement, I use denim insulation on the back of open-back and semi-open-back headphones, but it’s not perfect.)
In this chart, the external noise level is 75dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. The NightHawks’ isolation is roughly what I’ve measured from typical closed-back designs -- remarkable for a semi-open-back model. Consider AudioQuest’s claims for their diffuser confirmed.
The impedance magnitude of the NightHawks is basically flat, but my test gear measured it as 13 ohms -- much less than the specified 25 ohms. (I checked the test setup with a couple of other headphones; it was working properly.) The impedance phase, too, is basically flat.
The NightHawks’ sensitivity, measured between 300Hz and 3kHz with a 1mW signal calculated for the claimed 25-ohm impedance, averages 100.4dB -- enough to get plenty of volume from almost any source device.
. . . Brent Butterworth
brentb@soundstagenetwork.com
I measured the PSB M4U 4s using a G.R.A.S. Model RA0045 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 headphone amplifier. I used one of the supplied Comply foam eartips because that’s what designer Paul Barton used when voicing this model. For comparison, I also include a measurement taken with one of the supplied silicone eartips. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.
Here is the frequency response of the M4U 4s using a supplied Comply foam eartip. It’s fairly similar to the responses we measure with most high-quality earphones, the only aspects of note being a little more energy than usual around 1.5kHz, and a little less than usual from 8 to 10kHz.
This chart shows the M4U 4s’ frequency response with the Comply foam eartip (red trace), and with the smallest of the supplied silicone tips (purple trace). The silicone tip causes a boost of 2-3dB in upper-midrange/lower-treble energy, a deep dip at 7kHz, and a 3-10dB increase in output between 8 and 12kHz. PSB’s silicone eartips will likely sound significantly brighter.
Adding 70 ohms of output impedance to the V-Can’s 5 ohms to simulate the effects of using a typical low-quality headphone amp has only a very slight effect on the M4U 4s, boosting the bass by 0.8dB at 20Hz (this will be inaudible), and reducing the output between 2 and 3kHz by 0.5-1dB (might be barely audible). Most balanced-armatures headphone show a much bigger and more significant frequency-response swing in this test.
You can see from this chart that the M4U 4s (blue trace) have more bass and treble output than do NAD’s Viso HP20 earphones (green trace), also designed by Paul Barton, or Sony’s XBA-H1s (red trace), a well-regarded hybrid design.
Other than the bass resonances seen in almost every spectral-decay measurement of headphones, the M4U 4s are essentially resonance-free.
The M4U 4s’ total harmonic distortion (THD) is very low, with just a couple of slight, narrow peaks at 1 and 4kHz, where the THD rises to 2.5-5% -- and that’s only at the extremely loud level of 100dBA, measured with pink noise.
In this chart, the sound-pressure level (SPL) of external noise is 75dB; the numbers below that indicate the degree of attenuation of external sounds. With either the Comply (green trace) or the silicone (purple trace) eartips, the M4U 4s’ isolation is outstanding for passive earphones. In fact, I had to expand this chart’s Y axis to accommodate the traces; normally, the lowest number along the Y axis is 30dB.
Here’s why, unlike with almost all other headphones using balanced-armature drivers, the M4U 4s’ response doesn’t really change when the user switches to a high-impedance source device. The impedances of most balanced-armature ’phones increase radically at high frequencies, but the M4U 4s’ impedance remains between 18 and 22 ohms throughout the audioband.
The M4U 4s’ sensitivity, measured from 300Hz to 3kHz with a 1mW signal calculated for the claimed 16-ohm impedance, is 99.7dB. Technically, that’s a little lower than average for earphones, but it’s plenty high enough to get a satisfying volume level from any portable device.
. . . Brent Butterworth
brentb@soundstagenetwork.com
I measured the Bowers & Wilkins P5 Series 2s using a G.R.A.S. Model 43AG ear/cheek 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 headphone amplifier. I moved the headphones around to several different locations on the ear/cheek simulator to find the spot that gave the most bass and the most characteristic response. As I usually do with on-ear headphones, I used the ear/cheek simulator’s clamping mechanism to ensure a good seal. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.
This chart shows the P5 Series 2s’ frequency response. Its obvious distinguishing characteristic is the big dip in the midrange, centered at 500Hz. That peak, centered at 2.3kHz, is broad and high in amplitude, leading me to speculate that many listeners will find the P5s to sound a little bright. You may notice the disparity in bass response between the left (blue) and right (red) channels. That’s the best bass output I could get from the left channel after repeated repositionings of the earpiece, but keep in mind that the acoustical mating of the ear/cheek simulator to on-ear models is too fussy and unpredictable for me to take off points here.
Adding 70 ohms output impedance to the V-Can’s 5 ohms to simulate the effects of using a typical low-quality headphone amp has little effect on the P5 Series 2s other than a boost in the bass of about 1dB below 80Hz.
This chart compares the P5 Series 2 with a well-regarded on-ear model, Beyerdynamic’s T51p (red trace), as well as my reference headphones for the $300 price point: NAD’s Viso HP50s (green trace). These are normalized to 94dB at 500Hz, per my standard practice for headphone frequency-response measurements and as mandated by the IEC’s 60268-7 standard, which makes it look as if the P5 Series 2s have a lot more bass and treble output than the other headphones -- but it’s more accurate to think of them as having a huge midrange dip around 500Hz.
The P5 Series 2s’ waterfall plot looks very clean, with no noteworthy resonances.
The total harmonic distortion (THD) of the P5 Series 2s is typical for on-ear ’phones. At the loud listening level of 90dBA (measured with pink noise), the THD rises to 2% at 20Hz, which you’re very unlikely to notice (unless you often listen to Saint-Saëns’s “Organ Symphony”). At the very loud listening level of 100dBA, the THD runs about 4.5% below 40Hz.
In this chart, the external noise level is 75dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. With very little reduction of level in sounds below 1kHz, and none in the “jet engine band” of about 50-100Hz, this is typical performance for passive on-ear headphones.
The impedance of the P5 Series 2s is mostly flat, staying between 24 and 30 ohms through the entire audioband.
The sensitivity of the P5 Series 2s, measured between 300Hz and 3kHz with a 1mW signal calculated for the rated 22 ohms impedance, is 101.2dB. This is typical for on-ear headphones.
. . . Brent Butterworth
brentb@soundstagenetwork.com
I measured the Oppo PM-3s using a G.R.A.S. Model 43AG ear/cheek 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 headphone amplifier. Measurements were calibrated for ear reference point (ERP), roughly the point in space where the center axis of your eardrum would intersect with your palm if you pressed your hand against your earlobe. I moved the headphones around to several different locations on the ear/cheek simulator to find the one that produced the most bass and the most characteristic response. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.
This chart shows the PM-3s’ frequency response, which is just a little bit atypical in that the usual peak centered somewhere near 3kHz is more like a hill. So it’s a broader boost than usual, and the peak around 7.5kHz is a little stronger than usual. Thus, this measurement suggests a fairly neutral tonal balance but a somewhat unusual sound.
Adding 70 ohms of output impedance to the V-Can’s 5 ohms, to simulate a typical low-quality headphone amp, has essentially zero effect on the PM-3s’ frequency response.
This chart compares the closed-back PM-3s (blue trace) with Oppo’s open-back PM-2s (red trace) and NAD’s closed-back Viso HP50s (green trace). The PM-2s and HP50s obviously have flatter responses; the PM-3s are likely to be perceived as sounding more trebly than either.
The PM-3s’ waterfall plot is pretty clean, with much less bass resonance than the norm. The only noteworthy resonances in the mids and treble are centered at 2.1 and 3kHz. They’re well damped, though, and die out after about 8ms.
The Oppos’ total harmonic distortion (THD) is practically nonexistent. This is one of the lowest distortion figures I have measured in a set of headphones.
In this chart, the level of external noise is 75dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. This result is very good for over-ear (i.e., circumaural), passive headphones, with reductions of 10dB at 1kHz, and as much as 35dB at higher frequencies. However, it won’t have much effect on jet-engine noise, which is typically loudest between 50 and 200Hz.
The PM-3s’ impedance magnitude and phase are almost dead flat at 26 ohms -- the same as Oppo’s spec.
The sensitivity of the PM-3s, measured between 300Hz and 3kHz with a 1mW signal and calculated for the specified impedance of 26 ohms, is 99.8dB -- enough to get decent volume levels from most portable devices.
. . . Brent Butterworth
brentb@soundstagenetwork.com
I measured the Torque t402v headphones using a G.R.A.S. Model 43AG ear/cheek 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 headphone amplifier. Measurements were calibrated for ear reference point (ERP), roughly the point in space where the center axis of your eardrum would intersect with your palm if you pressed your hand against your earlobe. I moved the headphones around to several different locations on the ear/cheek simulator to find the one with the most bass and the most characteristic response. In measurements of the headphones with the on-ear earpad, I used the G.R.A.S. 43AG’s clamping mechanism to ensure a good seal. This was a “flat” measurement; no diffuse-field or free-field compensation curve was employed.
This chart shows the t402v’s frequency response with the over-ear pad in the four different sound modes. The traces are color-coded to the modes: yellow for yellow mode, blue for blue mode, etc. With all modes, there’s a fairly large midrange dip between 400Hz and 1.5kHz, and the peak between 5kHz and 8kHz is stronger than the peak at 3kHz. With most headphones, the 3kHz peak is stronger. Yellow mode measured as being a lot more bassy than the other modes.
This chart shows the frequency response with the on-ear pad, again color-coded by mode. This is a much more typical response than I measured with the over-ear pad, with a mild midrange dip centered at 750Hz and a moderate (for headphones) peak at 3kHz. The magnitude of the measured differences among the modes was less with the on-ear pad.
Adding 70 ohms to the V-Can’s 5-ohm output impedance to simulate the effects of using a typical low-quality headphone amp had little effect on the t402v. This result is normalized at 1kHz, per my standard procedure. A tiny peak in the impedance produced a slight and probably inaudible boost centered at 1.1kHz, but otherwise the impedance change in the source had no effect on the frequency response.
This chart compares the t402v with on-ear pad in black mode (dark blue trace) and over-ear pad in black mode (light blue) with NAD’s Viso HP50 over-ear model (red) and Beyerdynamic’s tunable Custom One Pro with its tuning level in position 2 “linear” (green). The HP50 obviously had the flattest response of the three; in on-ear and over-ear modes, the t402v was bassier than the other two.
The t402v’s waterfall plot is very clean, with much less resonance than I usually see in headphones of this type. You can see a mild resonance at that impedance peak centered at 1.1kHz, but because it’s well damped, it dies out almost immediately. The measurement shown was taken with the over-ear pad; the result with the on-ear pad was even cleaner.
The t402v’s total harmonic distortion (THD) was moderate with the on-ear pad, but higher with the over-ear pad because of the headphone’s lower sensitivity with the latter pad. In the above chart, results with the on-ear pad are shown in the dark traces, at 90dBA (dark green) and 100dBA (dark orange); results with the over-ear pad are shown in the light traces, at 90dBA (light green) and 100dBA (light orange). With the on-ear pad, the THD is fairly typical: at 90dBA, 1% at 100Hz and 3% at 20Hz, those numbers respectively rising to 2% and 7% at the very loud listening level of 100dBA. With the over-ear pad, the results at 90dBA (still quite a loud level) were similar to the 100dBA results with the on-ear pad, but at 100dBA the distortion was pretty high. However, it’s unlikely that you could reach such high levels with the over-ear pads installed if you’re driving these headphones with a phone or tablet.
In this chart, the level of external noise is 75dB SPL; the numbers below that indicate the attenuation of outside sounds. The green trace shows the t402v’s isolation with the on-ear pad, the purple trace the result with the over-ear pad. These results are typical for passive on-ear and over-ear headphones; you’ll get very little reduction of level in sounds below 1kHz.
The t402v’s impedance is essentially flat, averaging 18 ohms, with very moderate phase shift. As noted above, the Torque’s impedance does have a slight peak centered at 1.1kHz.
The sensitivity of the t402v, measured between 300Hz and 3kHz with a 1mW signal and calculated for the rated 16-ohm impedance in black mode, was 101.6dB with the on-ear pad and 93.9dB with the over-ear pad. The on-ear results are typical for closed-back headphones, but the over-ear results are low -- more like what I’d expect to measure from audiophile-oriented planar-magnetic headphones.
. . . Brent Butterworth
brentb@soundstagenetwork.com
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