I measured the Pryma 0|1s 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. I moved the headphones around to several different locations on the ear/cheek simulator to find the position with the most bass and the most typical average response. This is a “flat” measurement; no diffuse-field or free-field compensation curve was employed.

Frequency response

This chart shows the Pryma 0|1s’ frequency response, which looks largely flat, with perhaps a tad of extra bass, a little extra energy around 1kHz, and a little less energy around 3kHz than we usually see.

Frequency response

Adding 70 ohms output impedance to the V-Can’s 5 ohms to simulate the effects of using a typical low-quality headphone amp reduces the Pryma 0|1s’ upper bass very subtly: about 1dB between 80 and 240Hz.

Frequency response

This chart compares the Pryma 0|1s with three well-regarded closed-back competitors: NAD’s Viso HP50s, Bowers & Wilkins’s P7s, and Oppo Digital’s PM-3s. The Pryma 0|1s have the most downward-tilted (i.e., more bass, less treble) balance of any other of the headphones shown. Note that a flat measured response in headphones does not necessarily result in a flat perceived response, as it generally does with loudspeakers.

Waterfall

Other than a somewhat strong resonance centered at 950Hz, the Pryma 0|1s’ waterfall plot looks pretty clean.

THD

The Pryma 0|1s’ total harmonic distortion (THD) is a little higher than average at low frequencies. At the loud listening level of 90dBA, the THD hits about 1% at 100Hz, and 5% at 20Hz. At the extremely loud level of 100dBA (included more as a benchmark than as a representation of anything you’ll encounter in actual listening), it hits about 3% at 100Hz and 9.5% at 20Hz.

Isolation

In this chart, the external noise level is 75dB SPL; the numbers below that indicate the attenuation of external sounds. That the Pryma 0|1s offer 5-10dB less isolation than many other closed-back headphones (including the B&W P7s, PSB M4U 1s, and Oppo PM-3s, all shown here) is probably due to their relatively small earpieces.

Impedance

The impedance magnitude of the Pryma 0|1s averages about 35 ohms, and the impedance phase is nearly flat.

The sensitivity of the Pryma 0|1s, measured between 300Hz and 3kHz with a 1mW signal calculated for the rated 32 ohms impedance, is very high at 107.4dB -- any source device or headphone amplifier can drive them.

. . . Brent Butterworth
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