PSB Speakers M4U 2 Active Noise-Cancelling Headphone (Playback 59)

A Headphone for All Seasons

The famous Canadian firm PSB Speakers is the latest entrant in a growing group of speaker makers who have decided to enter the headphone marketplace, in this case with the introduction of the M4U 2 active noise-cancelling headphone ($400). But while PSB is not the first speaker maker to take up the headphone gauntlet, they may be one of the first to turn a designer of company founder Paul Barton’s formidable talents loose on an all-new, clean-sheet-of-paper design—and that make a concerted effort to put music first.

From the outset, the M4U 2 provides all the right features likely to make the product a commercial success. First, it is a noise-canceller, meaning that it steps into a proven, popular product category (just ask Bose). Second, it is—like all noise cancellers—a self-powered headphone, meaning that unlike many of today’s most ambitious $400 headphones it needs no outboard amplifier to sound its best. Third, it is set up to serve both as a headphone and as a headset because—for many thousands of listeners--smartphones have become the musical source components of choice. Fourth, the M4U 2 pays attention to all the little details so many competitors overlook: details such as ergonomics, beautiful industrial design, self-evident build quality, and exquisite packaging. But even with all these plusses going for it, we think the biggest plus of all is the M4U 2’s sound quality.

Here’s the deal; everything Mr. Barton has learned through decades of PSB speaker design has been poured directly into the M4U 2, and his experience makes a difference you can readily hear. As with his speaker designs, Barton has designed the M4U 2 so that it not only measures well in empirical lab tests, but also sounds good, as verified through carefully controlled listening tests. Barton has also leveraged his speaker-making expertise by deliberately voicing the M4U 2 to provide what PSB terms an “in-room” feel. In practice this means the M4U 2 response curve closely matches the in-room response characteristics of PSB loudspeakers—complete with a certain amount of low-frequency “room gain”, just as loudspeakers enjoy. Since most records are geared for playback through loudspeakers. Barton reasoned that it only made sense to give the M4U 2 a similar degree of bass lift. 

Going further, Barton also took an active role in creating the M4U 2’s amplifier/noise-cancelling system, striving to make it effective at blocking noise, yet also capable of preserving musical details and subtleties. Finally, Barton gave the M4U 2 a feature that, to our knowledge, no other noise cancelling headphone provides: namely, the ability to power up the headphone’s amplifier section without engaging the DSP-driven noise-cancellation circuitry, a step that reduces measured distortion considerably. Again this is a feature audio purists can easily hear and appreciate.

This review will address several different aspects of the M4U 2, including its design, ergonomic qualities, convenience features, and most importantly, its sound.

FEATURES

Basic Design, PSB M4U 2

• 40mm PSB-designed dynamic driver in a closed-back headphone.
• Built-in amplifier/noise cancellation circuitry powered by dual AAA batteries battery life is approximately 55 hours). Surprisingly, the M4U 2 uses what PSB terms a “low noise linear amplifier”—not a class D amplifier as found in many competing designs.
• Noise-Cancellation System: Unlike some competing noise-cancelling headphones, the M4U 2 uses an analog—not a DSP-driven—noise cancellation system that uses four built-in microphones to detect room noise, rather than the usual two mics. PSB comments that, “We found that there was more accurate noise measurement collection using four microphones instead of the usual two-microphone set up, which yielded better cancellation across a wider bandwidth when used with our low noise linear amplifier.”
• Tri-Mode design. The M4U 2 provides three distinct operating modes:

o Passive mode: The M4U 2 can easily be driven by iPods, iPhones and the like, even when battery power is switched off.
o Active mode: The M4U 2’s amplifier is turned on, but noise-cancellation circuitry is not engaged.
o Active Noise-Cancelling mode: Both the M4U 2’s amplifier and noise cancellation circuitry are turned on.

• Headphone voicing is said to provide an “in-room feel,” meaning that the tonal balance of the M4U 2 closely approximates the sound you would hear from high performance speakers in a typical listening room (complete with the “room gain” most loudspeakers enjoy).
• Distinctive Stereo Monitor function: Both signal cables provide an in-line switch labeled “M” to denote the Stereo Monitor function. Here’s how the function works relative to the M4U 2’s three operating modes.