Reviewed on: SoundStage! Solo, December 2020
I measured the Beyerdynamic T1 headphones using laboratory-grade equipment: a G.R.A.S. Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and a Clio 10 FW audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. The headphones were amplified using a Musical Fidelity V-CAN and Schiit Magnius. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.
The chart above shows the frequency response. This reminds me to some extent of the responses I often measured about eight years ago, with a big, resonant hump spanning the entire bass region and much of the midrange. We don’t see this as often now because bassy headphones aren’t so much in vogue anymore. Normally we’d see a big peak around 2 to 3kHz, but that peak has been shifted up in frequency, centering at about 6.5kHz. In this case, the measurements certainly match my subjective impressions.
This chart shows how the T1s’ tonal balance changes when they’re used with a high-impedance (75 ohms) source, such as a cheap laptop or some cheap professional headphone amps, or some exotic tube amps. The T1s will sound a couple dB bassier with a high-impedance source—so I’d recommend sticking with sources having an output impedance of 10 ohms or lower.
This chart shows the T1s’ right-channel response compared with several high-end headphones—including the Dan Clark Audio Æon 2 Closeds, which are the planar headphones I’ve found to measure closest to the Harman curve when they’re used with the optional perforated earpads. The T1s’ response is definitely different—with the curves normalized to 94dB at 500Hz, the T1s show a substantial upper-midrange dip (and thus a bass and treble boost) relative to the others.
The T1s’ spectral-decay plot shows no significant resonances.
Harmonic distortion in the T1s is a little on the high side. At the loud level of 90dBA (measured with pink noise), it rises above 2% only below 40Hz, which is unlikely to be audible. But at the extremely loud level of 100dBA, it hits about 7% at 40Hz—although even that probably won’t be troublesome, because the generally accepted threshold for audibility of distortion at these frequencies is about 10%.
In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. The isolation of the T1s is comparable to that of other large, open-back audiophile headphones; you can see how much better on this test that closed-back headphones such as the T5s are.
The T1s’ impedance magnitude has the resonant bass-impedance hump typical of dynamic drivers, rising to about 64 ohms in the bass, but averaging about 34 ohms above about 500Hz. Impedance phase angle is fairly flat, although there’s enough of a kink in the curve to produce that rise in the bass from high-impedance sources.
Sensitivity of the T1s, measured between 300Hz and 3kHz, using a 1mW signal calculated for 32 ohms rated impedance, is 101.1dB, so most source devices should get plenty of volume from them.
Bottom line: The T1 headphones have an idiosyncratic frequency-response curve, so try before you buy, but they present no other significant problems and are easy to drive.
. . . Brent Butterworth
brentb@soundstagenetwork.com
