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