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Parent Category: Products

Category: Headphone Measurements

Created: 01 April 2017

I measured the P9 Signatures 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, a Musical Fidelity V-Can headphone amplifier, and an Audio-gd NFB-1AMP amplifier for distortion measurements. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.

The elephant in the measuring room is the P9s’ wide, deep dip centered at 550Hz. If that dip were about 6dB less deep, it would be pretty close to what I’d call a textbook headphone frequency response. What does that mean in terms of sound? I hate to predict headphones’ sound based only on their measured frequency response, but that big dip sure won’t make voices sound more prominent.

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 amplifier. Using the higher-impedance source boosts the bass by a maximum 1.5dB, which will result in only a subtle difference in the sound.

This chart compares the P9s’ measured right-channel frequency response with those of two other high-quality closed-back headphones (Oppo’s PM-3s and B&W’s own P7s) as well as Audeze’s LCD-X open-back headphones, the last used as the comparison standard in the review. The fact that the P9s’ big midrange dip is centered very close to 500Hz -- the reference frequency for this measurement -- makes the P9s look more different than they really are from the others. Still, the P9s will likely sound the most different of the four.

The spectral-decay (waterfall) chart shows a narrow but strong resonance at 1kHz that might occasionally be audible, depending on what you’re listening to. There are also resonances at 2.8 and 3.6kHz, but they’re so narrow and low in magnitude that it’s hard to imagine they’d be audible.

The P9s’ total harmonic distortion (THD) is low for dynamic over-ear headphones, maxing out at 1% at 20Hz at 90dBA and 3% at 100dBA -- and 100dBA is extremely loud.

In this chart, the external noise level is 75dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. For comparison, I’ve included the isolation plots of other closed-back over-ear headphones: B&W’s P7s and Oppo’s PM-3s, plus Bose’s noise-canceling QC25s. The P9s’ isolation is about average, or maybe slightly above average, for this type of headphone.

Except at their impedance peak at 55Hz, the P9s average about 30 ohms impedance. Electrical phase is nearly flat.

The P9s’ sensitivity, measured between 300Hz and 3kHz with a 1mW signal, is 100.1dB, calculated for the specified 22 ohms impedance -- about average for closed-back headphones. In practical terms, this means that they’ll play at satisfyingly loud volumes with a Samsung Galaxy smartphone, and at very loud volumes with an iPhone.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 15 January 2017

I measured the Amiron Homes 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, a Musical Fidelity V-Can headphone amplifier, and an Audio-gd NFB-1AMP amplifier for distortion measurements. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.

The Amiron Homes’ frequency response is a little unusual. Typically we see a strong peak in the region of 2.5kHz, then one or two weaker peaks at higher frequencies. In the Amiron Homes, the peak centered at 7.5kHz is by far the strongest. I can’t recall seeing a response quite like this before, so I can’t speculate as to what its subjective effects might be.

Adding 70 ohms output impedance to the V-Can’s 5 ohms, to simulate the effects of using a typical low-quality headphone amp, boosts the Amiron Homes’ bass by about 1dB.

This chart shows the Amiron Homes’ measured frequency response compared with those of the HiFiMan HE560s (a similarly priced planar-magnetic open-back model) and the NAD Viso HP50s, my comparison standard for midpriced closed-back headphones. Except for that strong peak at 7.5kHz, the Amirons seem within the norm for headphone frequency response.

The spectral-decay (waterfall) chart indicates that the Amiron Homes have almost no resonances. What few there are are well damped and die out within a few milliseconds.

The total harmonic distortion (THD) of the Amiron Homes is negligible at 90dBA, almost nonexistent above 60Hz, and rises to just 3% at 20Hz. At the extremely loud level of 100dBA, the THD is comparably low above 60Hz but rises to 9% at 20Hz.

In this chart, the external noise level is 75dB SPL, and the numbers below that indicate the degree of attenuation of outside sounds. For comparison, I’ve included the isolation plots of the open-back HiFiMan HE560s, the closed-back NAD Viso HP50s, and the noise-canceling Bose QC25s. The Amiron Homes provide above-average isolation for open-back headphones -- nothing below 1kHz, but they decrease environmental noise by 11 to 17dB at frequencies above 2kHz.

Through most of the audioband, the Amiron Homes’ impedance is closer to 300 ohms than the specified 250 ohms, and rises to a peak of 690 ohms at 95Hz. There’s some mild phase shift on either side of that peak, but the impedance phase is relatively flat overall.

The Amiron Homes’ sensitivity, measured between 300Hz and 3kHz with a 1mW signal calculated for the specified 250 ohms impedance, is 102.4dB -- high enough for a typical smartphone to be able to drive the Amiron Homes to loud levels.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 01 January 2017

I measured the AF1120s using a G.R.A.S. Model RA0045 ear simulator (plus a Model 43AG ear/cheek simulator for isolation measurements), 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 a medium-size Comply foam tip because it fit the RA0045 best. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.

The AF1120s’ frequency response is unusually flat for earphones. Most earphones have more boost in the bass, and a fairly large response peak around 3kHz. In this case, however, flatter isn’t necessarily better. It’s generally considered best for earphones to have a somewhat stronger bass response and a stronger peak in the lower treble, which is thought to make them sound more like actual speakers in a room.

Adding 70 ohms output impedance to the V-Can’s 5 ohms, to simulate the effects of using a typical low-quality headphone amp, does affect the AF1120s’ tonal balance. This suggests that it would be unwise to use the AF1120s with a low-quality, high-output-impedance headphone amp, such as those built into typical laptop computers. With a high-impedance source (i.e., greater than 40 ohms or so), the AF1120s will likely sound too trebly. This relatively large difference in frequency response with high-impedance sources is typical for earphones using balanced-armature drivers.

This chart shows the AF1120s’ frequency response compared with two similar models, the PSB M4U 4s and the Optoma NuForce HEM8s. Notice how unusually flat the AF1120s’ response is. My subjective impressions were that the M4U 4s sound slightly trebly, while the HEM8s have a somewhat soft-sounding treble.

Despite the AF1120s’ no-frills plastic housings, their spectral decay (waterfall) chart is extremely clean, indicating no noteworthy resonances.

The total harmonic distortion (THD) of the AF1120s is insignificant at 90dBA, which is a pretty loud listening level. At the extremely loud level of 100dBA, the distortion rises to about 3% below 2kHz; that’s slightly on the high side, but if you listen long at this level you won’t have much hearing left anyway.

In this chart, the external noise level is 75dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. For comparison with the AF1120s, I’ve included the isolation plots of two similarly designed passive earphones, the PSB M4U 4s and the Optoma NuForce HEM8s, as well as the Bose QC20s, the last offering the best isolation of any earphones I’ve measured. The AF1120s deliver an average level of isolation for earphones with over-ear cable routing, which is to say an above-average level of isolation compared with other earphones and most over- and on-ear headphones.

Like most earphones using balanced-armature drivers, the AF1120s exhibit a large impedance swing in the treble. It rises from the specified 10 ohms at 100Hz to a peak of 42 ohms at 8.9kHz. The impedance phase also shows large swings throughout most of the audioband.

The sensitivity of the AF1120s, measured between 300Hz and 3kHz with a 1mW signal calculated for the rated 10 ohms impedance, is 109.8dB. That’s above average, which means that any source device should be able to drive these earphones to loud levels.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 01 December 2016

I measured the HE1000 V2s 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, a Musical Fidelity V-Can headphone amplifier, and an Audio-gd NFB-1AMP amplifier for distortion measurements. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.

The HE1000 V2s’ frequency response is about par for the course for headphones of this type, with flat response below 1kHz and strong treble response between 2 and 10kHz.

Adding 70 ohms output impedance to the V-Can’s 5 ohms, to simulate the effects of using a typical low-quality headphone amp, doesn’t affect the HE1000 V2s’ tonal balance. Still, a low-quality headphone amp may not deliver satisfying volume from the HE1000 V2s.

This chart shows the HE1000 V2s’ measured treble response compared with the original HE1000s and the Audeze LCD-Xes, another set of well-regarded, high-end, open-back headphones. The HE1000 V2s are similar to the original model, but with more treble response between 5 and 8kHz.

This spectral-decay (waterfall) chart indicates that the HE1000 V2s have the “Portuguese man-of-war” plot produced by many large planar-magnetic headphones, with many extremely high-Q (narrowband) resonances, as well as a fairly high-magnitude resonance centered at 5kHz.

The total harmonic distortion (THD) of the HE1000 V2s, measured with pink noise, is practically nonexistent: just 1% at 20Hz, even at the extremely high test level of 100dBA.

In this chart, the external noise level is 75dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. For comparison, I’ve included the isolation plots of the original HE1000s, the Audeze LCD-Xes, and the NAD Viso HP50s, which are midpriced, closed-back headphones. As usual, the open-back models offer almost no isolation from outside sounds.

The HE1000 V2s’ impedance is almost dead flat at 35 ohms; their impedance phase response is also flat.

The sensitivity of the HE1000 V2s, measured between 300Hz and 3kHz with a 1mW signal calculated for the specified 35 ohms impedance, is 86.9dB. That’s very low; consider a decent headphone amp with at least 6dB more output than an iPhone essential to get the best performance from these headphones.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 01 November 2016

I measured the second-generation T 5 p 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. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.

Although the frequency response of the T 5 p headphones looks somewhat uneven, the measurement suggests a fairly flat overall tonal balance, with a little extra energy around 8kHz -- which is probably why I perceived the sound as being slightly bright.

Adding 70 ohms output impedance to the V-Can’s 5 ohms to simulate the effects of using a typical low-quality headphone amp shows that the T 5 p’s are only subtly sensitive to the source impedance, with a boost of about 1dB in the bass and treble response reduced by about 0.5dB. Thus, with a high-impedance source, the T 5 p should sound slightly warmer.

This chart of the Beyerdynamics’ measured treble response is more or less within the ballpark for high-end headphones. However, their bass response appears to be stronger than average for audiophile headphones -- stronger than Audeze’s closed-back, planar-magnetic LCD-XCs, or Sennheiser’s open-back, dynamic-driver HD 800 Ses.

The spectral decay (waterfall) plot of the Beyerdynamics is fairly clean, with just one pretty well-damped resonance at 8kHz (this corresponds with the response peak at that frequency), and less bass resonance than I usually measure in closed-back ’phones.

The total harmonic distortion (THD) of the T 5 p’s is low, evident only in the bottom octave of bass and only at high listening levels. Note that most of the distortion harmonics remain within the bass range; e.g., the fifth harmonic of 30Hz is 150Hz.

In this chart, the level of external noise is 75dB SPL; numbers below that indicate the degree of attenuation of outside sounds. The T 5 p’s provide a little more isolation from such sounds than do Audeze’s LCD-XCs, another audiophile-oriented, closed-back headphone model.

The impedance of the T 5 p’s is fairly flat, ranging from 32 to 45 ohms with a relatively flat phase curve.

The Beyerdynamics’ sensitivity, measured between 300Hz and 3kHz with a 1mW signal calculated for the specified 32 ohms impedance, is 103.4dB. That’s fantastic for large, audiophile-oriented headphones, and enough to ensure loud volume from almost any source device.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 15 October 2016

I measured the Sonorous IIIs 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, a Musical Fidelity V-Can headphone amplifier, and an Audio-gd NFB-1AMP amplifier for distortion measurements. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.

The Sonorous IIIs’ frequency response is flatter than I’m used to seeing from headphones of this type. Instead of the usual response peak around 3kHz, which is generally thought to make headphones sound more like speakers in an actual room, there’s a broad, shallow peak between 1.5 and 6kHz. I can’t recall seeing a measurement like this before, so I hesitate to speculate as to what effect it might have on the sound. I wonder if the lack of a 3kHz peak is why the Sonorous IIIs sounded a bit less spacious than some competing models.

Adding 70 ohms output impedance to the V-Can’s 5 ohms, to simulate the effects of using a typical low-quality headphone amplifier, has no significant effect on the Sonorous IIIs’ tonal balance.

This chart shows the Sonorous IIIs’ response compared with two well-regarded, midpriced closed-back models: the NAD Viso HP50s ($299) and the Oppo Digital PM-3s ($399). It’s easy to see that the Sonorous IIIs are something different, with less treble response than either competitor. But that’s not necessarily a bad thing -- the Sonorous IIIs’ somewhat rolled-off bass could counteract it, to give the headphones a perceived flat response.

Their spectral-decay (waterfall) plot indicates that the Sonorous IIIs seem to have a bit stronger initial resonance below 700Hz than I’m used to seeing, but it’s well damped, and drops to very low levels (-40dB and below) within 5 milliseconds.

The total harmonic distortion (THD) of the Sonorous IIIs is very low. Even at the extremely loud level of 100dBA, it rises to just 3% at 20Hz.

In this chart, the level of external noise is 75dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. For reference, I’ve included another set of passive closed-back headphones, the NAD Viso HP50s, as well as that of a set of headphones with active noise canceling: the Bose QC25s ($299). The Sonorous IIIs’ isolation is not quite as good as the Viso HP50s’, probably because the Finals’ large earpads made it tough to get a good seal on the ear/cheek simulator (and on my actual, unsimulated ear and cheek). As always with this measurement, your results may vary; the better the fit, the better the isolation.

The Sonorous IIIs’ impedance is essentially flat, averaging 19 ohms, with negligible phase shift.

The sensitivity of the Sonorous IIIs, measured between 300Hz and 3kHz with a 1mW signal calculated for the specified impedance of 16 ohms, is 105.8dB. That’s excellent for headphones of this type; there should be no problem getting loud volumes from any source device.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 15 September 2016

I measured the Audeze Sines 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. In most cases, I used the G.R.A.S.’s clamping mechanism to ensure a good seal of the earpad against the simulator’s fake rubber ear. For all but one measurement, I used the standard analog cable. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.

The Sines’ frequency response is typical of planar-magnetic headphones, except that there’s more bass rolloff than I usually see. There’s also not a lot of energy in the upper treble, above about 6kHz. I was occasionally able to measure more bass than you see here, depending on how I positioned the headphones on the ear/cheek simulator, but this chart represents the result I got about 90% of the time.

Because my test equipment doesn’t have an Apple Lightning output, and I have no device that will convert the Clio’s S/PDIF output to Lightning, I had to compare the Sines’ performance from the digital and analog inputs using a relatively crude technique: playing pink noise from my iPod Touch through the Sines using both cables, and comparing the results using TrueRTA with 1/12th-octave smoothing. Still, my method clearly shows that the sounds via the two cables are substantially different. Using the digital cable results in considerably more bass output: +3.9dB at 50Hz. Considering that the Sines’ bass with the analog input was unaffected by changes in source impedance, my guess is that this difference reflects an intentional engineering choice to boost the bass with the digital cable.

Adding 70 ohms output impedance to the V-Can’s 5 ohms to simulate the effects of using a typical low-quality headphone amp shows that the Sines will be somewhat sensitive to source-device impedance when used with the analog cable. With the higher-impedance source, the lower-treble response is boosted by 2.8dB at 2.6kHz.

This chart shows that the Sines have a more midrange-focused sound than two other midpriced closed-back models, NAD’s Viso HP50 and Oppo Digital’s PM-3; both of these have stronger bass and upper-treble responses.

The Sines’ spectral decay (waterfall) plot shows a broad area of resonance between 1.5 and 6kHz, but these resonances drop quickly in level, and are gone within 5ms.

The total harmonic distortion (THD) of the Sines is pretty close to zip, even at extremely high listening levels.

In this chart, the level of external noise is 75dB; the numbers below that indicate the degree of attenuation of outside sounds. The Sines have about the same amount of isolation as another midpriced, closed-back headphone model, NAD’s Viso HP50.

The Sines’ impedance is flat at about 22 ohms, except for a 40-ohm peak centered at 2.5kHz. The phase response is almost entirely flat, except for a mild wrinkle that corresponds with the impedance peak.

The sensitivity of the Sines, measured between 300Hz and 3kHz with a 1mW signal calculated for the rated 20 ohms impedance, is 96.6dB -- a little low. This is enough to produce decent volume from a smartphone or tablet, but if you like to crank the sound up loud, use the digital cable or a separate headphone amp.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Measurements

Created: 01 September 2016

I measured the HD 630VBs 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. In most cases, I used the clamping mechanism on the Model 43AG to ensure a good seal of the earpads against the simulator’s fake rubber earlobe. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed. Except as noted, measurements were made with the Variable Bass (VB) control in the middle setting.

The HD 630VBs, measured here with the VB dial set to its midpoint, have an idiosyncratic frequency response. Obviously, there’s a large dip between 150 and 600Hz. The peak in the 2-3kHz range, a prominent feature of most headphones’ measured response, is unusually broad, spanning the range from about 1.5 to 4kHz, and there’s a strong peak centered at 8kHz. This is the best match I was able to achieve between the left and right channels; it’s possible the inclusion of the VB control on the right earpiece has some effect on the acoustics of that earpiece.

This chart shows how the VB control affects the HD 630VBs’ response. The control’s operation is not linear; the magnitude and bandwidth of its effect are much greater between the middle and Max positions than between the middle and Min positions. Sennheiser specifies the control’s range as +/-5dB at 50Hz, which is accurate. At 20Hz, the adjustment range is +/-8.8dB. The control has no significant effect above about 800Hz.

Adding 70 ohms output impedance to the V-Can’s 5 ohms to simulate the effects of using a typical low-quality headphone amp suggests that the design of the source device will have considerable effect on the HD 630VBs’ sound. The response, measured with the VB control in the middle setting, is considerably different with the two source impedances. Unsurprisingly, however, the difference is in the range where the VB control is effective; when users adjust the bass control to their taste, they will likely dial out any effect of the source impedance on the headphones’ response.

This chart shows that the HD 630VBs’ voicing is considerably different from that of two well-regarded, closed-back, over-ear models, NAD’s Viso HP50 and Sennheiser’s own Momentum. The HD 630VBs’ output is much lower between 150 and 400Hz, and significantly greater between 3 and 5kHz.

The HD 630VBs’ spectral decay (waterfall) plot shows three prominent resonances, all at a very high Q and a low level of about -40dB; I suspect that these are inaudible. There is a low-Q resonance band between 2 and 4kHz, but the resonance is at only -20dB, and dies out in less than 4ms; this resonance is a result of a peak in the headphones’ response, so it can be considered a part of the HD 630VBs’ sound rather than an audible flaw. The resonance below 1kHz is visible in this measurement with almost every headphone I test; the HD 630VBs’ resonance is lower than average.

The total harmonic distortion (THD) of the HD 630VBs is low, maxing out at 2% even at the extremely high output level of 100dBA. This measurement was taken with the VB control at its midpoint setting.

In this chart, the external noise level is 75dB SPL; numbers below that indicate the degree of attenuation of outside sounds. The HD 630VBs are a little above average for passive closed-back headphones, with 6-10dB of additional noise reduction between 200 and 400Hz compared to the NAD Viso HP50s, closed-back headphones with isolation measurements that are typical for their type. This is especially useful because it’s within the “jet-engine band,” the most prominent noise in a typical airliner cabin.

With the VB control at its middle position, the HD 630VBs’ impedance runs from 100 ohms in the bass to 24 ohms in the midrange. The phase shift is modest, maxing out at +32 degrees at 20kHz.

The VB control has a large effect on the HD 630VBs’ impedance at low frequencies. With the control set to Min, the impedance measures 242 ohms at 20Hz; at Max, it’s 30 ohms at 20Hz; and at the midpoint setting it’s 100 ohms.

The sensitivity of the HD 630VBs, measured between 300Hz and 3kHz with a 1mW signal calculated for the rated 23 ohms impedance, is 100.6dB. This means that a smartphone or tablet should be able to drive the HD 630VBs to adequate volume levels.

. . . Brent Butterworth
brentb@soundstagenetwork.com