Headphone Reviews

Measurements
The Bowers & Wilkins P5 is a 27 ohm headphone that is quite efficient to drive, delivering 90dB SPL at 51mVrms. It will easily reach solid listening levels on portable devices.

Frequency Response

Significant variability in both bass and treble response is evident in the raw data measurements in the bottom half of the chart above. Spatially averaged and HRTF compensated frequency response in the upper traces show the P5 has a nearly flat response well into the lower bass registers. B&Ws claim of 10Hz response at the low end is not an exaggeration, and this performance in the lows is superior to any headphone of this type I have measured.

From 200Hz to 10kHz the response is substantially even, but tilted toward the warm side. Listening tests confirm that, though warm, these cans are otherwise well behaved and balanced.

Frequencies in the highest octave (between 10kHz and 20kHz) is somewhat hit and miss with position (this was also heard in listening tests). I believe B&W could have dialed in just a bit more up top without being fatiguingly bright, but, when positioned well, I found ample highs for good intelligibility.

Impedance and Phase Response

Impedance response shows a 27 ohm headphone with a primary driver resonance at 2.2kHz, and the phase response shows a headphone that will behave rather well even with headphone amplifier sources that have relatively high output impedance.

THD%+noise

THD%+noise results were very good showing a maximum of about 0.8% through the mid-range at 90dB SPL. THD remaining quite low in the bass indicates a very good seal, and long and accurate driver excursions. This indicates excellent tightness of bass response when heard. The 100dB curve resting generally below the 90dB response indicates the headphones have excellent power handling capabilities.

30Hz Square Wave

A fairly flat top with a trailing edge that remains above zero indicates excellent linearity and coherent bass response. Rounded leading edge is indicative of a warmish sound.

300Hz Square Wave Response

Leading edge spike is not too high and damps reasonably well indicating a headphone that is not harsh, but rather longish time period of the feature and the upward tilt of the top of the square wave tends to mean not enough high frequency response and/or and overabundance of bass.

Impulse Response

The impulse is positive going indicating properly polarized drivers. The rather short initial spike and longish period of the ring indicate poor high frequency response. However, the impulse is pretty much damped out by 700uSec indicating a headphone that is coherent and tight.

Isolation

The Isolation of the P5 is excellent for a headphone of this type; delivering about 16dB of broadband noise attenuation. B&W's claims of good isolation with some outside input for situational awareness is accurate.