Tuesday, September 19, 2017

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I measured the B200s using a G.R.A.S. RA0045 coupler (with a Model 43AG ear/cheek simulator used 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 the supplied medium-size silicone eartips, which best fit the RA0045. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.

Frequency response

The B200s’ measured performance is a little flatter than average for earphones, though that doesn’t necessarily mean they’ll sound flatter. Relative to the peak at 2.4kHz, the output above 5kHz is a little lower than I’m used to seeing, which suggests that the B200s won’t sound bright.

Frequency response

This chart shows the results of adding 70 ohms output impedance to the V-Can’s 5 ohms, to simulate the effects of using a typical low-quality headphone amp. Balanced-armature earphones usually show an audible difference on this test, but this result is comparatively extreme; using a source with a high output impedance -- such as the headphone amps built into many laptops -- will result in a much brighter sound.

Frequency response

This chart shows the B200s’ measured right-channel frequency response compared with those of three other earphones using balanced armatures or a combination of balanced armatures and dynamic drivers: 1More Quad Driver, Audiofly AF1120, and PSB M4U 4. The B200s measure roughly as flat as the AF1120s; this test suggests that the AF1120s will sound moderately brighter than the B200s.

Waterfall

Despite the B200s’ lightweight plastic enclosures, the spectral-decay (waterfall) chart shows no noteworthy resonances above about 300Hz, and less bass resonance than I often see in similar earphones.

THD

The B200s’ total harmonic distortion (THD) is insignificant, maxing out at just over 1% at 20Hz at the extremely loud level of 100dBA.

Isolation

In this chart, the external noise level is 75dB SPL; the numbers below that indicate the B200s’ degree of attenuation of outside sounds. For comparison, I’ve included the isolation plots of three other earphones: the Audiofly AF1120 (with over-ear cable routing), the 1More Quad Driver (with standard cable routing), and the Bose QC20, a model with active noise canceling that has the best performance I’d previously measured on this test. If memory serves, the B200s’ is the best measured result on this test that I’ve gotten from passive earphones -- in fact, I had to move the bottom of the measurement scale down to 20dB SPL to make the B200s’ result visible. According to this test, at least, the B200 won’t quite match the state-of-the-art Bose QC20 in the “airliner-cabin band” of about 100Hz to 1kHz, but it should do an even better job of blocking the noise of the ventilation system, crying babies, etc. Of course, isolation heavily depends on how well the eartips fit your ear canals; my subjective results weren’t so impressive because the largest of the Brainwavz’ included tips didn’t perfectly fit my ears. As always with earphones, your mileage may vary.

Impedance

Like most headphones employing balanced-armature drivers, the B200s show a large impedance swing: about 15 ohms up to 300Hz, then rising to a peak of 145 ohms at 7kHz. The electrical phase doesn’t swing as radically, but it still varies quite a lot, from +45 to -38 degrees. This isn’t unexpected, given the B200s’ driver configuration, but it does mean that switching from a source with a low output impedance to one with a relatively high output impedance will change the sound significantly.

The B200s’ sensitivity, measured between 300Hz and 3kHz with a 1mW signal, is 116.1dB calculated for the specified 30-ohms impedance. This means that the B200s will play at a very loud volume from any conventional source device, even a $20 MP3 player.

. . . Brent Butterworth
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