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Parent Category: Products

Category: Headphone Measurements

Created: 10 December 2018

Reviewed on: SoundStage! Solo, December 2018

I measured the R-220s 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 new KB5000 and KB5001 anthropomorphic simulated pinnae for most measurements, and the stainless-steel coupler included with the RA0045 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 R-220s’ frequency response measured with the KB5000 and KB5001 anthropomorphic simulated pinnae. Above 1kHz, this measurement looks typical for earphones. But below 1kHz, there’s a lot less bass than we usually see.

This chart shows the R-220s’ right-channel frequency response measured with the RA0045 ear simulator’s stainless-steel coupler (which I’ve used for years) and the new KB5000 simulated pinna, which I recently switched to because it more accurately reflects the structure and pliability of the human ear and provides a more realistic simulacrum of what you’ll actually experience with headphones or earphones. This is just for sake of comparison with older measurements of mine.

As usual with earphones incorporating balanced-armature drivers, the R-220s show a tonal balance shift when you go from a low-impedance source device (typically between 0.5 and 5 ohms) to a relatively high-impedance source device (typically 75 to 125 ohms). In this case, the bass and lower midrange will be attenuated by about 1dB, and the treble boosted by 2 to 3dB.

This chart shows the R-220s’ right-channel response compared with two other earphones in the same price range (the Campfire Comets and the Acoustic Research AR-E010s used in wired mode), as well as the AKG N5005s, the earphones that currently best conform to the “Harman curve,” shown in research by Harman International to be the preferred in-ear headphone response for most listeners. Again, the R-220s’ response is much more heavily balanced toward the treble than the other models -- even the AR-E010s, which have only a little more bass but also balance out the sound with a somewhat reduced treble response.

The R-220s’ spectral decay (waterfall) chart shows only an extremely high-Q (i.e., narrow) and weak (-40dB) resonance around 5kHz. There’s no chance this would be audible.

The R-220s’ distortion is modest for balanced-armature earphones, running about 1% at the loud listening level of 90dBA, and 2% at the extremely loud level of 100dBA.

In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The R-220s’ isolation (shown with and without its flange) is about average for earphones of this type, maybe a little above average between 500Hz and 1kHz.

Most balanced-armature earphones show some impedance swing, but the R-220s show a little more than most, rising from the rated 29 ohms below 500Hz to a high of about 130 ohms at 20kHz. The phase also swings a lot, from 0 degrees in the bass to +60 degrees at 20kHz. This is why the sound changes with high-impedance sources.

Sensitivity of the R-220s, measured between 300Hz and 3kHz, using a 1mW signal calculated for the rated 29 ohms impedance, is 97.2dB. That’s low for earphones; the reason for the low number is that the response is skewed toward the treble. So the upper mids and treble will be a lot louder than that, but the bass will be lower.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 01 December 2018

Reviewed on: SoundStage! Solo, December 2018

I measured the Solarises 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 new KB5000 and KB5001 anthropomorphic simulated pinnae for most measurements, and the stainless-steel coupler included with the RA0045 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 Solarises’ frequency response measured with the KB5000 and KB5001 anthropomorphic simulated pinnae. This is pretty standard response for earphones, except that they have less bass and treble response (or more midrange response) than we usually see. The measurement here was done with medium-size Campfire Marshmallow foam tips. I also tried using the supplied medium-size silicone tips, and the result was almost identical.

This chart shows the Solarises’ right-channel frequency response measured with the RA0045 ear simulator’s stainless-steel coupler (which I’ve used for years) and the new KB5000 simulated pinna, which I recently switched to because it more accurately reflects the structure and pliability of the human ear and provides a more realistic simulacrum of what you’ll actually experience with headphones or earphones. This is just for sake of comparison with older measurements of mine.

Here you can see how the Solarises’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop or some cheap professional headphone amps. As usual with earphones incorporating balanced armature drivers, there’s a tonal balance shift when you go from a low-impedance source device (typically between 0.5 and 5 ohms) to a relatively high-impedance source device (typically 75 to 125 ohms). In this case, the bass and lower midrange will be attenuated by 2 to 4dB relative to the treble. Note that this measurement is normalized to 1kHz; it would probably be more accurate to say the treble output from the balanced armatures is boosted by 2 to 4dB and the bass from the dynamic driver stays about the same.

This chart shows the Solarises’ right-channel response compared with a few other midpriced earphones: the Fidue A85 Virgos, Campfire’s own Comet earphones (which cost less than one-seventh as much, but I was curious to see if there was a family resemblance), and the AKG N5005s, the earphones that currently best conform to the “Harman curve,” shown in research by Harman International to be the preferred in-ear headphone response for most listeners. The Solarises’ response does look similar to the other brands, just flatter.

The Solarises’ spectral decay (waterfall) chart shows no significant resonance at any frequency within the range of this measurement (i.e., above 200Hz).

The Solarises show a little more distortion than I’m used to seeing in high-end earphones, and the distortion seems to be coming mostly from the midrange driver; it’s about 1 to 2% at the fairly loud level of 90dBA, and a little above that at 100dBA. That may seem like a lot of distortion if you’re used to looking at amplifier distortion numbers, but in speakers, headphones, and earphones, this level is barely, if at all, audible.

In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The Solarises’ isolation is maybe a hair better than average for large earphones, although a small earphone such as the Campfire Comet (also shown here) may achieve somewhat better isolation because it can go a little deeper into the ear.

The Solarises’ impedance response is very low in the bass, at about 3 ohms. Once the balanced armatures kick in, it rises to 7 to 11 ohms, and the phase shifts positive. This is why the tonal balance changes with high-impedance source devices.

Sensitivity of the Solarises, measured between 300Hz and 3kHz using a 1mW signal calculated for 10 ohms impedance is 115.7dB, which is very high for high-end earphones.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 10 November 2018

Reviewed on: SoundStage! Solo, November 2018

I measured the XFree Tunes 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 new KB5000 and KB5001 anthropomorphic simulated pinnae for most measurements, and the older KB0065 right pinna for certain other measurements as noted. For measurements in Bluetooth mode, I used a Sony HWS-BTA2W Bluetooth transmitter to get the signal to the earphones. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed.

The above chart shows the XFree Tunes’ frequency response measured in Bluetooth mode with the new KB5000 and KB5001 anthropomorphic simulated pinnae. If that upper bass hump centered at about 150Hz were instead centered at about 70Hz, this would be pretty close to a “textbook” frequency response for over-ear headphones.

This chart compared the response of the XFree Tunes using Bluetooth versus using a wired connection. There is bass roll-off below 50Hz with the Bluetooth connection, but otherwise the plots are effectively identical. It’s possible that the roll-off could be due to the signal gating I had to use to counteract Bluetooth’s latency, but I got the same result no matter how I set the gate, so I suspect the bass roll-off is inherent to the sound of the XFree Tunes in active (i.e., Bluetooth) mode.

This chart shows the XFree Tunes’ right-channel frequency response measured with the KB0065 simulated pinna (which I’ve used for years) and the new KB5000 simulated 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 XFree Tunes’ tonal balance changes when they’re used with a wired connection into a high-impedance source, such as a cheap laptop or some cheap professional headphone amps. There’s barely any change at all, just a roughly 1dB drop in bass response centered at about 55Hz.

This chart shows the XFree Tunes’ right-channel response compared with two other over-ear headphones in Bluetooth mode with noise canceling off: the NAD Viso HP70s and the Bowers & Wilkins PXes. I also included Sony MDR-7506es, the over-ear model that currently best conforms to the “Harman curve,” shown in research by Harman International to be the preferred over-ear headphone response for most listeners. While it’s difficult to determine exactly what headphones sound like based on comparison charts like this, it’s pretty clear that the XFree Tunes have some excess upper bass energy, perhaps to offset their relatively modest bass response.

The XFree Tunes’ spectral decay (waterfall) chart looks clean except for some resonance around 300Hz, but it’s down to -30dB within 12ms, which is equivalent to four cycles at 300Hz.

The XFree Tunes show significant distortion only at the extremely loud listening level of 100dBA, and only below 100Hz. At the still-very-loud level of 90dBA, the distortion measurement is about average for a dynamic-driver over-ear model, and there’s not enough distortion that you'd be likely to notice it. This was measured with a wired connection; the internal amps of the XFree Tunes may add some distortion, but my analyzer can’t compensate for Bluetooth’s latency when doing distortion measurements.

In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The XFree Tunes’ isolation is about average for over-ear headphones without active noise canceling.

The XFree Tunes’ impedance response is very close to flat, averaging about 37 ohms and staying within a tolerance of ±2dB.

Sensitivity of the XFree Tunes with a wired connection, measured between 300Hz and 3kHz using a 1mW signal calculated for the rated 32 ohms impedance, is 106.7dB, so you don’t have to worry about getting adequate volume when you plug into an airliner’s inflight entertainment system.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 20 September 2018

Reviewed on: SoundStage! Solo, September 2018

I measured the Base Audio G12s 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, and an Audio-gd NFB-1AMP for the distortion measurements. 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 above chart shows the G12s’ frequency response with their standard earpads installed. This is a nearly by-the-book response for headphones, with response peaks centered at approximately 2.6 and 5.5kHz, a response generally considered to deliver a sound close to that of speakers in a room. What’s unusual is that the treble is a bit elevated relative to the bass, which corresponds with our listening impressions.

This chart shows the G12s’ 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 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.

Here you can see how the G12s’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop or some cheap professional headphone amps. Turns out they’ll have a little more bass with high-impedance sources -- they might actually sound better with a cheap laptop!

This chart shows the G12s’ right-channel response compared with those of two modestly priced open-back headphone models, the Monoprice M650 and HiFiMan HE400i, as well as Grado Labs’ RS2e. (The Grados cost $495, but I wanted to include measurements of a Grado model, and this was the only one I had on hand.) The G12s are clearly more trebly than the M650s but, according to the measurements, slightly less trebly than the HE400i’s, and much less trebly than the RS2e’s.

The G12s’ spectral-decay (waterfall) chart shows a little bit of resonance that corresponds with the response peaks in the upper mids and treble, but they’re well damped.

Though the measured total harmonic distortion (THD) of the G12s is negligible above 130Hz, it’s a little on the high side below that, though none of the listeners noticed any distortion in their tests.

In this chart, the external noise level is 85dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. The G12s’ isolation is about average for open-back headphones: a little better than the HiFiMan HE400i’s, not quite as good as the Beyerdynamic Amiron Homes. If you want better isolation, you’ll need to get a closed-back model such as the NAD Viso HP50s, also shown here.

The G12s’ impedance runs about 19 ohms, except in the region around 55Hz, where it rises to 31 ohms. This corresponds with the difference I measured in the 5 vs. 75-ohm sources. The phase response is generally flat, except for a mild flip at the frequency of the impedance peak.

The sensitivity of the G12s, measured between 300Hz and 3kHz with the leatherette earpads and using a 1mW signal calculated for the rated 32 ohms impedance, is 99.4dB. That’s reasonably high for audiophile-oriented headphones; you should get good volume from the G12s with practically any source component.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 10 September 2018

Reviewed on: SoundStage! Solo, September 2018

I measured the Monoprice Monolith M650s 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, a Musical Fidelity V-CAN amp, and an Audio-gd NFB-1AMP for the distortion measurements. 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 above chart shows the M650s’ frequency response with its leatherette earpads installed, which is how the headphones are shipped. This is the best match I was able to achieve between the left and right channels. I’m not sure if the difference was due to a genuine difference in the two drivers’ responses, or to the not-quite-mirror-imaged profiles of the simulated left and right pinnae I use. (No human being’s ears are precise mirror images of each other either, by the way.) That said, the right-channel trace is very close to accepted standards of what constitutes a natural-sounding tonal balance for headphones, with a strong peak at 3kHz; a second, weaker peak at 7.2kHz; and a large (and somewhat higher than might be expected) bump in the bass response.

This chart shows the difference in right-channel response of the M650s with their leatherette and velour earpads installed. While the shape of the response curves is mostly the same, the velour pad subtracts 2 to 5dB of bass and adds 3 to 10dB of treble, producing a response curve more typical of open-back headphones.

This chart shows the M650s’ right-channel frequency response with the leatherette earpads, 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 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.

Here you can see how the M650s’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop or some cheap professional headphone amps. Even though the M650s show a large impedance peak in the bass, there was barely any difference in response when I switched from a 5-ohm source to a 75-ohm source -- probably because the M650s’ impedance phase is relatively flat.

This chart shows the M650s’ right-channel response with the leatherette and velour earpads, compared with two modestly priced open-back headphones: the HiFiMan HE400is and the Sennheiser HD 598s. The M650s have a bit more bass response with the velour pads installed, and a lot more bass response with the leatherette pads.

The M650s’ spectral decay (waterfall) chart shows something unusual: what appears to be resonance across most of the audioband. Maybe the driver isn’t as well damped as most. But there really aren’t any high-Q (strong, narrow) resonances except below 300Hz, so I doubt any of this would be especially audible.

The M650s’ measured total harmonic distortion (THD) is low for headphones, hovering at around 1% or 2% even at the very loud levels I use for this test.

In this chart, the external noise level is 85dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. Note that the M650s’ isolation with the leatherette earpads is pretty good for open-back headphones, but it’s nowhere near as good with the velour pads. As with most other open-back models (in this case, the HiFiMan HE400i and Massdrop Sennheiser HD 6XX headphones), the M650s in no way approach the isolation of closed-back headphones such as the Sony MDR-7506es, also included in this chart.

The M650s’ impedance response looks pretty typical for dynamic-driver over-ear headphones: the impedance generally hovers near the rated 64 ohms, rising to a peak at the 80Hz driver resonance. The phase response is impressively flat for a relatively large dynamic-driver model.

The sensitivity of the M650s, measured between 300Hz and 3kHz with the leatherette earpads using a 1mW signal calculated for 64 ohms impedance, is 107.5dB. That’s pretty high for audiophile-oriented headphones; you should get pretty good volume from the M650s regardless of the source component you use them with.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 01 September 2018

Reviewed on: SoundStage! Solo, September 2018

I measured the Fidue Virgos 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 headphone amplifier. I used the RA0402 as a direct coupler for most measurements, adding the Model 43AG plus the G.R.A.S. KB5000 simulated pinna for certain measurements, as noted. I used the included medium-size silicone tips for measurements with the coupler, and the Comply foam tips for measurements with the ear/cheek simulator. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed.

The most prominent feature of the Virgos’ frequency response is that their peak in the 3kHz region -- generally considered to mimic ear-canal resonance and to let earphones deliver a decent simulation of hearing speakers in a room -- is higher in magnitude than usual. This suggests that they’ll sound a little bright. However, the energy above 4kHz is a bit lower than average, which suggests that they might not have as airy or ambient a sound as some competitors.

This chart shows the Virgos’ right-channel frequency response measured using only the RA0402 coupler (which has a stainless-steel tube into which earphones fit), and measured using the Model 43AG ear/cheek simulator with G.R.A.S.’s new KB5000 pinna, which I’ll be switching to eventually 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 result of 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. Most earphones having one or more balanced-armature drivers per earpiece show a substantial measured difference with this change, but the Virgos show almost none. This suggests that the Virgos will have the same tonal balance no matter what source device or amp you use them with.

This comparison chart shows that the Virgos’ 3kHz peak is relatively strong; in the competitors, the 3kHz peak is somewhere around the level of the peak in the bass response.

The spectral-decay (waterfall) chart looks clean, with some strong but very-well-damped (i.e., non-ringing) resonance corresponding to that strong 3kHz peak.

The Virgos’ total harmonic distortion (THD) is low, nearly zero, except for a relatively low-magnitude, high-Q peak near 1kHz. Even at the extremely loud listening level of 100dBA, the peak is narrow and weak enough that it’s very unlikely to be audible.

In this chart, the external noise level is 85dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. I included measurements with the silicone eartips and the Comply foam tips because with the Virgos, the choice of tip makes a significant difference. This level of isolation is not as good as I’ve seen from some other earphones with over-ear cable routing, such as the Massdrop x NuForce EDC3; I’d guess that’s because they’re relatively large and don’t nestle as tightly into the ear/cheek simulator’s fake pinna. Your mileage may vary.

The Virgos’ impedance is unusual for hybrid earphones. Almost all earphones having one or more balanced armatures per earpiece have huge impedance and phase swings in the treble region, but with the Virgos these swings are very mild, more in the range of variance I’d expect to see in earphones having only dynamic drivers. Again, this suggests that the Virgos’ sound will be consistent, regardless of the output impedance of the source device.

The sensitivity of the Virgos, measured from 300Hz to 3kHz with a 1mW signal at the specified 20 ohms impedance, is 111.3dB. You’ll get ample volume from any source device.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 20 August 2018

I measured the Viso HP70s 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 headphone 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 certain 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 HP70s’ frequency response, shown here with noise canceling (NC) on in Bluetooth mode, looks mostly conventional. The squarish bump in the bass response below 150Hz corresponds pretty closely to the recommended bass response of the so-called “Harman curve,” which research shows is what most listeners prefer in headphones. The peak centered at 2.8kHz is standard for headphones because it makes them sound more like speakers in a room, though in this case it’s a little on the low side relative to the bass bump. Many headphones have a dip at about 5kHz, and another smaller peak centered somewhere around 8kHz, but the HP70s show a smoother, more gradual rolloff above the 2.8kHz lower-treble peak. This suggests that these headphones may sound a little on the mellow side.

This chart shows how the HP70s’ frequency response differs when in Bluetooth with NC on and off, and in wired mode with power off. The NC has very little effect on frequency response, which is an excellent and, sadly, rare result. Wired mode does change the sound, but it actually pushes the response closer to what I see in average headphones -- while it will sound different from the Bluetooth and/or NC modes, it probably won’t sound jarringly different.

This chart shows the HP70s’ measured right-channel frequency response with BT and 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 begin using only the new pinna.)

This chart shows that the HP70s are more or less in the same ballpark as their sister model, PSB’s M4U 8 (also designed by Paul Barton), and Sony’s WH-1000XMK2; here, the clear outliers are Bowers & Wilkins’s PXes. Note, though, that the HP70 is the only model shown that doesn’t have a dip in the 5-6kHz range.

This spectral-decay (waterfall) chart shows the results in wired mode; the latency introduced by Bluetooth prevented me from getting a reliable measurement in that mode. You can see some minor resonances at about 2, 4, 5, and 7kHz, but they’re well damped and shouldn’t be very audible, if at all. The little bit of resonance creeping in down around 200Hz may correspond with the bass bump below 150Hz.

Because of latency problems with Bluetooth, I had to measure the total harmonic distortion (THD) of the HP70s in wired mode. Distortion is negligible; even at the very loud level of 100dBA, there’s only about 3% distortion in the bass -- that might seem as if it would be audible, but the generally accepted threshold for the audibility of harmonic distortion in bass frequencies is 10%.

In this chart, the external noise level is 85dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. Paul Barton told me that, compared with the M4U 8s’ NC chip, the HP70s’ NC chip is better at some frequencies and worse at others. This chart bears out that claim: the HP70s look better from about 90 to 150Hz, but the M4U 8s clearly outperform the HP70s from 150 to 1000Hz -- and approach the high standards set by the Sony and Bose models also shown here.

The HP70s’ impedance magnitude in wired mode is nearly flat in magnitude and phase, averaging about 38 ohms with negligible phase shift.

The sensitivity of the HP70s, measured from 300Hz to 3kHz with a 1mW signal calculated for 32 ohms impedance, is 110.3dB in wired mode with power off. They’re sure to deliver all the volume you could want if you’re watching a movie on an airplane and the battery runs down.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 10 August 2018

I measured the ATH-ANC700BTs 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 headphone 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 certain 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 ATH-ANC700BTs’ frequency response, shown here with noise canceling (NC) on in Bluetooth mode, looks strange for a couple of reasons: the abrupt dip in the midrange and lower treble between 800Hz and 3.5kHz, and a lower/mid-treble response peak centered at 5kHz instead of the more usual 3kHz. It seems unlikely that this tuning would result in a natural, uncolored sound.

This chart shows how the response of the ATH-ANC700BTs differs when in Bluetooth with NC on, and in wired mode with NC on and power off. The responses with NC on don’t differ dramatically from Bluetooth to wired mode except in the bass, where there’s a peak at 65Hz. The wired mode with power off looks even stranger, with a huge peak centered at 500Hz -- something I’ve never seen before. Incidentally, measuring the wired connection with 70 ohms impedance added to the V-CAN’s 5-ohm output impedance produced a mild tilt in tonal balance, boosting bass and cutting treble by 1dB each.

This chart shows the ATH-ANC700BTs’ measured right-channel frequency response with BT and 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’m including 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.

The ATH-ANC700BTs’ big midrange/lower-treble dip is put in perspective by this chart, which compares them with two other BT/NC models, the PSB M4U 8s and Sennheiser HD 4.50 BTNCs.

This spectral-decay (waterfall) chart shows the results in wired mode with NC on; the latency introduced by Bluetooth prevented me from getting a reliable measurement in that mode. There’s a lot of resonance below 1kHz, which corresponds with the shelf in the frequency response below 800Hz. There are also some unusual, extremely narrow (high-Q) resonances in the treble, but they’re so narrow, and so low in amplitude (-40dB), that I can’t imagine they’d be audible. (The black boxes in the lower left corner of the graph are there because the gating on this measurement reduces resolution at low frequencies.)

Because of latency issues with Bluetooth, I had to measure the total harmonic distortion (THD) of the ATH-ANC700BTs in wired mode; this measurement was taken with NC on. Distortion below about 150Hz is much higher than I’m used to seeing, even at 90dBA. I normally caution that, because my measurements are taken at loud levels, most of the distortion you see in the measurements probably isn’t audible at normal listening volume -- but I suspect that the bass distortion visible here might be audible. I measured a couple of other headphones at the same time and got normal measurements on this test. I also confirmed this result by shutting down and restarting the Clio analyzer, recalibrating the levels, and repeating the measurements, but the result was essentially the same.

In this chart, the external noise level is 85dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. To interpret this, keep in mind that jet-airliner cabin noise tends to be loudest between 80 and 1000Hz, and the loudest part of that band is the low-frequency hum between 80 and 200Hz. The ATH-ANC700BT reduces noise pretty well, by about -15dB, between 80 and 200Hz, but doesn’t do much from 200 to 1000Hz -- which corresponds with Rad’s comment about the NC seeming to shift the noise up into the midrange.

The ATH-ANC700BTs’ impedance magnitude in wired mode averages 32 ohms with power off (full passive mode) and about 130 ohms with NC on. Phase is mostly flat in both modes.

The sensitivity of the ATH-ANC700BTs with a wired connection and NC off (full passive mode), measured between 300Hz and 3kHz with a 1mW signal calculated for the rated 35 ohms impedance, is 106.1dB. That should be plenty enough volume if you’re watching a movie on an airplane and the battery runs down.

. . . Brent Butterworth
brentb@soundstagenetwork.com