First Listen: Oppo PM-1 planar magnetic headphones

Back before the turn of the year, I received a message from Jason Liao, Oppo Digital’s Chief Technology Officer and Vice President of Product Development, asking if I would like to sample a very early prototype of Oppo’s new PM-1 planar magnetic headphone. Naturally, I said, “Yes, I’d love to try it,” and a few days later an unmarked box from Oppo appeared in my office.

The headphones within that box showed a great deal of promise, but also some sonic shortcomings and of course came with almost no accessories or documentation. Even so, what I could see and hear about the product based on my experiences with that early prototype made me all the more eager to hear the final production version.

Early this year, at the CES 2014 event, Hi-Fi+ Associate Publisher Pete Trewin and I had the opportunity to meet with Jason Liao and to compare notes on the PM-1 over lunch. But our luncheon turned out to involve a special surprise in that we also got to meet the designer of the PM-1, who turned out to be none other than the planar magnetic driver guru Igor Levitsky (the man who is the guiding technical force behind the well-regarded planar magnetic driver-equipped loudspeakers from the US-based firm BG Radia).

Through longstanding familiarity with Levitsky’s work for BG Radia, I already had a very favourable impression of Mr. Levitsky’s technical skills and insights, so I was pleased to learn that he was contributing his expertise and know-how to the design of the PM-1. In our ensuing CES discussion, it turned out that both Jason and Igor had heard and noted the very same shortcomings in the PM-1 prototypes that I had observed and they already had a plan in place to address them.  Accordingly, we decided that instead of doing a blog to describe the prototype PM-1s (which were about to be rendered out of date), it would be better for me to wait until the production versions were ready and then to do a blog.

Well, the auspicious moment is at hand, since just a few days ago a carton bearing the distinctive Oppo logo and the model “PM-1” designation appeared on my desk, containing one of the very first production samples of the PM-1 headphone (priced at $1,099). This blog will serve to share with you the unboxing experience, plus some preliminary and admittedly minimalist observations on the headphone’s sound (naturally, a full-on Hi-Fi+ product review will follow at a later date).

From the minute the shipping carton is opened, it becomes obvious that the PM-1 is a product Oppo hopes you will take very, very seriously. Inside the extensively foam padded shipping carton is a large, beautiful, fabric-covered box that looks like the sort of container in which one might expect to find, say, an expensive and exquisite porcelain tea service from Asia. Once the lid of the fabric-covered box is lifted one finds—another fabric covered box with small ribbon-type pull-tabs that allow the panels of the inner container to be opened. And inside that inner box user’s will find something rare and valuable: namely, a gloss-lacquered, dark wood (perhaps rosewood?) presentation case with the Oppo logo inset into the case’s top panel and a tasteful, inset pushbutton release catch that allows the case to be opened.

Inside the case, whose padded interior is lined with a soft fabric, one finds the PM-1 headphones themselves, plus a small oblong box sheathed in a black fabric bag. Inside that small, oblong box one finds the primary signal cables for the PM-1.  The whole opening sequence conveys (and I presume is meant to convey) a sense of occasion—kind of like the experience of unboxing a fine, handmade Swiss watch, but on a larger physical scale. No doubt about it: Oppo wants us all to get the message that, as we sometimes say in the US, the PM-1 headphone is “kind of a big deal.” And indeed it is.

Down beneath all these multi-layered boxes and cases, down in the bottom of the PM-1 shipping carton, one finds a padded canvas carry case for the PM-1s, plus a spare set of ear cup pads, and a second, differently configured signal cable. To review, then, the PM-1 package includes:

• A fabric-covered outer box.
• A lacquered wood presentation case.
• A set of PM-1 headphones, which ship with a set of beautiful perforated leather-covered ear cup pads installed.
• An alternate set of velour-covered ear pads for those who prefer fabric or dislike the feel (or politics) of leather.
• A primary 3 metre long signal cable terminated with a 6.35mm TRS-type headphone plug.
• An alternate 1 metre long signal cable terminated with a 3.5mm mini-jack headphone plug.
• A canvas-covered, padded carry case for the PM-1.
• A nicely executed User’s Manual.

Of the technology used in the PM-1, Oppo has this to say:

“The PM-1 utilizes a planar magnetic driver that sets it apart from the majority of headphones on the market. In our planar magnetic headphone, sound is generated by a very thin and light diaphragm whose entire surface area is evenly driven. The diaphragm is driven in a symmetric push-pull manner, and the magnetic system and conductor patterns have been optimized for maximum sensitivity and consistency.”

This description is all well and good, but frankly it could just as well apply to some, though not all, of the other planar magnetic headphones on the market today. However, no sooner does this thought pass through one’s head than one goes on to read this statement from Oppo:

“Unique to the OPPO PM-1 is the use of a double-sided diaphragm, which allows us to place twice as many conductors within the magnetic field and eliminated any passive return zones where the conductors do not work. This results in the use of 100% of our conductor length, which in turn results in greater efficiency. In addition, our flat conductor pattern eliminates inductance-related intermodulation distortion, common with dynamic headphones, and the OPPO PM-1’s purely resistive impedance means that sound quality is unaffected by a Headphone amplifier’s output impedance.”

Then, the final surprise comes when the manual states:

“The OPPO PM-1 combines high sensitivity with low weight, allowing it to be used freely with portable devices without requiring additional amplification.”

Just how high is the PM-1’s sensitivity? Oppo quotes a sensitivity rating of 102dB at 1mW, making the PM-1 (to our knowledge) by far the most sensitive of all top tier planar magnetic headphones. To see what I mean, let me cite sensitivity specifications for some of the industry’s best-loved planar magnetic models, below:

·      Abyss AB-1266: 85 dB

·      Audeze LCD-3: 91 dB

·      Audeze LCD-X: 96 dB

·      Audeze LCD-XC: 95 dB

·      Audeze LCD-2: 90 dB

·      HiFiMAN HE-6: 83.5 dB

·      HiFiMAN HE-500: 89 dB

·      HiFiMAN HE-400: 92.5 dB

The point, here, is that Oppo has pushed the sensitivity envelope farther than any other planar magnetic headphone maker to date, with the result—borne out in my preliminary listening tests—that one truly can listen to the PM-1 (and happily so) when driven by nothing more than a garden-variety iPhone. That’s impressive.

PRELIMINARY LISTENING

As above, the following are just some quick, ‘snapshot’ impressions of the PM-1 taken on the basis of a few brief, ‘getting-to-know-you’ listening sessions. They should NOT be construed as a full-fledged review and are subject to revision as I gain more listening time with the headphones.

First, as above, the PM-1 is remarkably sensitive and very, very easy to drive. In practice, this means you would choose an amplifier, if indeed you even decide you want to use one, more on the basis of sonic qualities than with an eye toward making sure your amp has ‘enough’ power (with this headphone, just about anything puts out ‘enough’ power).

I would say the PM-1 exhibits a just slightly warmer-than-neutral tonal balance that gives the headphone voicing reminiscent, at least to some degree, of the Audeze LCD-3. The midrange is richly nuanced and quite revealing, yet smooth as can be with no apparent peaks, rough edges, or signs of overshoot or ringing. The bass is also well detailed and decidedly full-bodied, though not ‘full-bodied’ in a way that would suggest low-frequency bloat or looseness. Highs are also exceedingly smooth, though they may also be just a touch recessed. I’m uncertain on this point, though, in that I really need to try the PM-1s with a broader range of amps and DACs than I’ve used thus far in order to draw more relevant conclusions (it may be that I’ve used warm-sounding and slightly rolled-off DACs thus far, in which case the Oppo is simply showing me the sound of the upstream components used to drive it).  Stay tuned for more developments and deeper commentary later on.

One point I would make is that the PM-1 is absolutely NOT one of the headphones where you have to squint your eyes and grit your teeth, working hard to enjoy the sound. On the contrary, everything about the Oppo—including both the physical feel of the headphone and its sound—is as comfortable and naturally relaxing as a weekend afternoon spent wearing a favourite pair of blue jeans and walking shoes. This comfort factor is, I think, a rare and valuable thing whose importance is often overlooked; it’s the sort of factor that spells the difference between a product that is exciting for the first 20 minutes or so versus one you want to keep using for hours on end.

We’re still in the early going, here, but my instinct is that Oppo has a runaway winner on its hands with its PM-1 headphone. Give a pair a listen and see what you think.

One final thought: Did I mention that the build quality and all-around fit and finish of this headphone are simply superb?  They are. Indeed, my educated opinion is that many other manufacturers could learn a lot by closely studying Oppo’s impressive workmanship in every aspect of this headphone.

Watch for the upcoming Hi-Fi+ review of the Oppo PM-1 and until then, happy listening to you and yours.