Anyone serious about audio knows that headphones have had a renaissance recently. Despite fancy plastic, flat cables, and prices based on endorsements by current music stars, most headphones are more alike than they are different. Headphones come in a few basic varieties; the most common is the dynamic design, which is really just a small traditional speaker – easy to make, capable of punchy sound, and strong bass, but essentially a piston that pushes sound. The next variety is known as electrostatic. It is much more esoteric, and uses a special transformer to charge a metallic film. The sound produced is often wonderful, but very expensive, and suitable only for desktop use due to the transformer.
In recent years we have seen the rise in popularity of a headphone design known as the planar magnetic design. These headphones use a plastic film usually with metallic traces on it and surrounded by powerful magnets. When the metallic traces are energized by an electric signal from the headphone amplifier, the film vibrates to create sound. Most planar headphones are inefficient, heavy, large, and expensive, but known for their excellent sound quality typified by precise soundstage placement, at least until now. I grew up with Magneplanar speakers, so I was familiar with their audio footprint and goals, but they were always a niche product. The late lamented, scandal-ridden Monsoon speakers from Canada were another attempt at creating an affordable planar for the desktop. Monsoon still has a strong following to this day despite the inglorious end of the company, and I have my own set in my office to this day, with some damaged ribbons, but even then a reminder of the open, airy sound planar's are known for.
One advantage of the planar design is that because they are not actual inductors and resistive in nature, their output isn’t affected by an induction, which means in essence that they shouldn’t create their own electrically induced audio problems. They are tricky to design and manufacture, and normally the magnets inside are rather heavy - not a desirable property for something designed to sit on your head for hours at a time. Why bother with planar, you ask? It’s a reasonable question, and the answer lies in their lightning-fast response to transients, a flat plane for reproduction that reduces phase and timing issues, and an open and airy sound that for the best models opens up the soundstage for precise rendering of instrument placement.
Oppo Digital, the respected manufacturer of award winning Blu-ray decks, has entered the fray with a new line of personal audio products, the first of which is the newly released PM-1 Planar Magnetic Headphones. The first mention that Oppo was working on a set of headphones set the audiophile world abuzz.
Now the rumors are over. Last month, after three years of development, beta testing, and more testing, Oppo began shipping the finished PM-1 Planar Magnetic Headphones, a high-end, luxury branded product that breaks new ground in performance, fit and finish, and sound quality. At $1,099 these are aimed at the serious audiophile, and even at that lofty price point are actually a bargain compared to their competition. I’ve been working with them for over a month, listening to just about every variety of music, with differing DACs and amplifiers and in all cases, the PM-1 surpassed my expectations, revealing nuances to music that I felt I already knew well. In the near future a less expensive version, the PM-2 is slated to ship, with the same transducers, but forgoing some of the luxury metal parts and features in favor or higher yields high-quality plastic for some parts.
I was lucky enough to be able to view and listen to a prototype of the PM-1 and the HA-1 headphone amplifier during the Consumer Electronic Show in Las Vegas in January 2014, where Jason Liao and Igor Levitsky showed me their new babies. Along with John Mulhern III, we listened to the PM-1 using an Astell & Kern player. It sounded great, but we were in a somewhat noisy environment, so I had to wait until a couple of days later when I could hear them paired with the HA-1 for a few minutes in the Oppo suite. They sounded even better in the quieter suite, but Jason reminded me that what I was listening with were engineering prototypes, almost final, but alas not the final shipping product, so I’d have to wait a bit longer. Still, even at that stage, it was pretty clear that Oppo was onto something; there was a good reason so many folks were excited about them.
Levitsky commented on several design challenges he was concerned with, from creating an open and musical sound quality to insisting on high-efficiency so the headphones would work well with a variety of hardware driving them, to wanting them to be neutral yet not sterile. From Liao’s point of view, one of the largest challenges was actual production. The quality level they were aiming at meant that a very limited set of suppliers would actually be able to produce product at such a high standard of quality. One reason for the higher cost of the PM-1 is the rejection rate for finished parts and components, especially for cosmetic flaws.
When I asked why the suppliers chose to work with Oppo given the dual constraints of short product runs and impossibly high standards, Liao laughed and said he was grateful they did, and that he thought that they were on board with the goals Oppo was trying to accomplish, so the relationship went beyond the financial bottom line. They seemed to be just as excited as Oppo was to be part of such a groundbreaking new product, which is our good luck. As mentioned before, Oppo has addressed this in part with their upcoming PM-2 headphones, which will use the same transducers, but do away with some of the luxurious touches such as the calfskin ear pads, the cherry wood case, and some metal components, in favor of precision plastics to lower the price significantly, but the expectation is that the audio signature will be very similar to the PM-1.
From Prototype to Shipping:
Jump from January to late April, when I received shipping confirmation that the final unit from Oppo was waiting. The first impression was that it was one heavy box for a pair of headphones! I had my teen-aged son pick up the box, and asked him what he thought was in it. His guess was maybe a Blu-ray player or something similar, due to the weight. Inside the box we found another two boxes; one was the optional headphone stand, and the other was a beautiful box, and within it a beautiful cherry wood veneer box, complete with a whiff of the finish - that new headphone luxury smell! Nested inside was a soft case for portable use, and some extra velour ear pads and cables. First-class packaging for a first-class product.
Opening the cherry wood box revealed the headphones, which were lighter than I remembered or expected. The primary cable is beautifully made with a substantial cloth covered OCC cable. All fittings are solid and well designed, with the gravitas that a product of this caliber deserves. The cables have small mono mini-jacks that go into each side of the headphones, with tiny L & R indicators.
I plugged in the long cable to use with my laptop, and looked for a step-down adapter to a mini-jack from the ¼-inch phone plug, but there wasn't one, but among the extra cables in the case I found the short OFC 3.5mm mini-jack cable that terminates in a mini-jack plug, perfect for use with most portable USB powered DACs, such as the AudioEngine D3, Cambridge Audio DacMagic XS, or the Korg DAC 100m, as well as most phones, music players, or computers. This is an important consideration since the PM-1s are the first planar design we have ever seen that is so efficient, they can be used with your phone, or computer, all without so much as a hiccup. The copper in the mini-jack cable is high-quality OFC (oxygen-free copper), so reputably not as good sounding as the OCC (Ohno continuous cast) copper used in the ¼-inch cable. To be honest any difference in sound quality that I heard was likely due as much to the choice of DAC or source as it was the composition of the copper. Either way you will never hear music from your phone the same way again! The Audioengine D3 was our favorite portable USB DAC with the PM-1, providing a seamless, warm, and musical sound signature that belies it's affordable price point.
I found the length of the cable perfect for use with a phone or player in my pocket, but a bit too short for desktop use, and Oppo has confirmed they are looking into offering a longer 1.8m version in the future which should be perfect for desktop use, or if you keep your player in a coat pocket on the go. While we are on the subject of cables, I was able to listen using a prototype Oppo Balanced Cable that uses OFC for the PM-1 with the HA-1, and while I loved the solidity of the physical connection, I was hard pressed to hear any difference in sound quality, but it remains an option for users with balanced output amplifiers. The current shipping version of the balanced cable uses OCC and matches the standard cable.
How to typify the sound? To my ears, as well as to my friends and colleagues who listened to the PM-1s were all in agreement that the sound was superb. The sound footprint is effortless, subtle, and neutral, but with a bit of warmth and a believable musicality. At no time did I "hear" the headphones or technology; they simply moved out of the way so that my experience was of listening to music, not technology. Sauntering over to Head-Fi.org, the biggest complaint posted about the PM-1s isn’t about the actual sound quality. Instead there seemed to be some sort of audiophile sour grapes that they sounded so good, with so little need for esoteric environments or equipment to drive them.
Folks do seem to feel that they need 50 hours of so of break-in to open up their bass response, but from my notes, I really didn’t notice a difference, and given the impossibility of accurately ascertaining the sound quality between new and broken-in, I tend to chalk that up to psycho-acoustics as much as anything tangible, and I didn't have a new set with no use to compare new vs. used, to ascertain any difference, which would seem the only accurate way to actually judge this. Memory is tricky, and since few of us can remember what something sounded like a week ago, trying to actually say that break-in changed something physical is a tough prove.
I did ask Oppo about this, and they said from the manufacturing point-of-view, one thing they aim for is absolute consistency, so while some folks make lots of claims for break-in, logic tells us that if a product needs X amount of time to break-in, that the break-in can’t be consistent, so we would see a ton of variance, all of which would fly in the face of manufacturing a consistent product. I took notes when I first listened to the PM-1’s, and after plugging them in, playing music on them for 50 hours or so, I couldn't really state with any certainty that they sounded any different. I can say that I probably changed my listening approach as I got used to them, but not that the PM-1’s sounded changed, they sounded just as wonderful the two weeks later as they had the day they arrived.
That being said, a few weeks later when Oppo sent us the HA-1, their new DAC and Class A headphone amplifier, the PM-1s really showed off their chops. During CES John and I assumed the HA-1 and PM-1 were sort of a matched pair, and while they certainly sound wonderfully together, the HA-1 is designed to be a universal headphone amplifier, so should be viewed in that light. I’m not saying the combination isn't a match made in heaven, but in reality the development of the PM-1 occurred separate from that of the HA-1, so I view them as individual, distinct products. That being said, Igor Levitsky told us how impressed he was with the HA-1, especially in combination with the PM-1s, an observation that my own use agreed with.
Many of the planar designs I've used seem very demanding of the amplifier employed, but the PM-1s are nowhere near that finicky. I did find a richer, fuller sound with higher output sources, such as the BDP-105, so I think that when paired with a dedicated high quality headphone amp, these phones will really hit their peak. My tests with HA-1 and the PM-1s revealed an incredibly substantial soundstage and attack, so I suspect that there will be a unique synergy when the PM-1s are paired with users’ existing amps.
Many audiophile products have the feel of being one step away from a test bench, with extraordinarily high quality gear and components, but their actual execution seems to be just shy of completely professional fully finalized product runs. This makes sense in light of the fact that even the more successful audiophile brands usually manufacturer products in the tens, hundreds, and occasionally the thousands, but nowhere near the levels of mass market products sold in big box retail stores, no matter how good. Consequentially, part of the joy of those products is in knowing that they aren’t cranked out in a giant factory, but are lovingly hand-assembled, and as result, there can be variability from unit to unit. Oppo, on the other hand, wanted an absolutely consistent audiophile experience, and the finished products show that this goal was achieved.
The finished PM-1s have the same extraordinary quality one would expect at this price point; I don't think I’ve ever worn a more comfortable headphone in my life. Lighter maybe, flashier yes, but these are comfortable after hours of use, consistently cool, and effortless to use and wear. There wasn’t a stitch on the calf-skin ear pads that was out of place, not so much as a smudge on the high-gloss finish of the wooden case, or the metal components on the headphone band. A look at the transducer revealed the intricate and inherently complex design, yet it wasn’t really necessary. What was necessary was to listen to music, not equipment, but music. I used Decibel, Pure Music, and Amarra to test the PM-1’s with, all of which worked splendidly with the DACs I employed.
The PM-1s have no flaws that we could discern. Throw the hard sharp metallic drum whack from Keith Richards first solo album, Talk is Cheap, at the PM-1s and you can feel the drum sticks hammering the skins. Punching rock and roll at them revealed a headphone that loved being driven hard, hard enough to make me feel almost as if I passed out under a snare drum. Content like this really took off when I switched to the HA-1 whose Class A bottom end seemed, well… bottomless; it seemed almost impossible to overdrive them without causing hearing loss.
Switching to Beck’s 2002’s Sea Change and 2014’s Morning Phase, using high-resolution files from HD Tracks, the PM-1s’ subtle attention to nuance, made the thwack of the drum stick I’d heard on Talk is Cheap seem miles away. Could these really be the same headphones? What I found most interesting was that as much as I’ve listened to the HD Tracks version of Sea Change was what I was not hearing. Any good system will reveal the aching beauty of that album, but the PM-1s sort of stepped back a bit, allowing the overtones to mix anew. On the HD Tracks version of the newly released Morning Phase, a new recording with intentional distortions, I expected to hear dramatic changes in texture, assuming that the decade of technology improvements in recording would reveal themselves, but instead what the PM-1s revealed was a more mature, possibly less optimistic, wearied voice. What I didn’t hear was the headphones. Just for fun I switched to some old favorite headphones and was astounded at how sterile and tiring they felt. Back to the PM-1s and it was clear my observation wasn’t a fluke. The PM-1s made Beck’s voice sound like a voice, not an approximation.
This is not to say that they soothe over the bumps without notice. Last year when we reviewed the recent Van Morrison Moondance remaster, we expressed some surprise at the album’s sound quality after this long-awaited remastering project, and while that album has never sounded better than as through the PM-1s, they also revealed the limitations of that decade-old remastering job compared with the newer mastering employed on the unknown tracks remastered and released for the first time last year. With the right source material, and amplifier, these are revelatory headphones.
The newly remastered releases of the first three Led Zeppelin albums came just in time to play on the PM-1s, and they revealed the strengths of the new versions. HD Tracks kindly supplied me with the high-resolution 96/24 bit Deluxe releases, which contained a mix of sampling rates, from 44/24, 48/24, in addition to the 96/24 rate for the majority of the tracks. The dynamic range seemed fine, not quite as much as the original CD release, but much better than some recent versions. The new versions feature some interesting extras, including a live concert recorded at the start of the bands formation with just a bit better then bootleg quality, but fun nonetheless, and various mixes, but I was curious how the PM-1s would handle the blues based bombast the first three albums introduced. Page is known for talking about the fact that after having been the veteran of hundreds of studio recordings, he knew what he wanted, and didn’t want in their records, and expected studios to deliver high-quality audio quality.
Can a headphone that loves Chesky Records “The Ultimate Headphone Demonstration Disc” revealing in its high-resolution impeccably mic’d audio, varied and sterling performances, handle the bottom end of John Paul Jones, Jimmy Page’s searing guitar work, John Bonham’s not-so-gentle smashing of drumheads, and Robert Plant’s vocals which range from almost guttural to falsetto? The answer is yes, and without breaking a sweat. The punch of the drums is there, as well as air in the room. The new versions certainly reveal that the PM-1 can rock and roll, as well as handle the gentle nuances of classical and jazz content. For the Zeppelin fan, not only are the new releases worth serious consideration, you can also rest assured that the PM-1s are up to the challenge, with punch and heft to the sound, so much so that you had better have a bottle of a decent bourbon nearby!
Back to the PM-1s vaunted efficiency. They worked well with my MacBook Pro, new DACs such as the new Korg DS-DAC-100M, the Cambridge Audio DacMagic XS, the AudioEngine D3, and the Oppo BDP-105 headphone amp. In all cases, they drove the headphones splendidly, which was a really pleasant surprise. To be honest, while they were described as efficient, I really didn’t expect them to perform as well as they did with all those different sources, especially USB-bus powered DACs which must live with the limitations imposed by the USB 2 500-milliamp current limit specification.
In fact, they were more efficient than many of my dynamic headphones, which really kind of shocked me. I was curious how they sounded using the Oppo BDP-105 headphone amp, which instantly proved the limits of lower-current handling DACs especially in the bottom end. We recently returned from a trip where my son borrowed them to use with his cell phone, and he thought they were fine, which meant that they worked as he expected them to, loud enough, comfortable for the entire 2-hour ride, and that they sounded great, just as a headphone should. I doubt that I could try this with many other planar models, or even some of my more esoteric dynamic models. That he ignored the fact that they were expensive “audiophile” headphones, and just got on listening to music seemed very reaffirming. It really reminded me of how flexible the PM-1s are, yet without sacrificing superb audio performance in more demanding environments and source material.
In our review of the HA-1 we discussed the family resemblance between the two products, but while the headphone amp in the BDP-105 is very good, and running directly from the ESS Sabre DACs, it is instructive to compare it to using the HA-1 with the PM-1s since one is required to use a computer, and player software for the most part, introducing new variables into the scheme. There are advantages to the BDP-105 approach, by grabbing the signal from the DACs, the BDP-105 avoids the hassles and technical issues imposed by third-party software, DACs, and amplifiers, and the more I listened to the BDP-105 the more impressed I was, but switching to the HA-1 really did reveal a different audio signature with the ability to use active equalization, and more tweakability. Suffice it to say, the PM-1s are so good that given a solid amplifier that they come into their own, and reveal the voicing that Levitsky was aiming for.
There are other superb planar headphones from other manufacturers, but most of them seem to have more singular strengths, or are more finicky and high-maintenance in their choice of supporting equipment, as well as being heavier and not nearly as comfortable. One of the strengths of the PM-1 is their ease of use, which I’m sure is upsetting to some gear-heads, but to us is one of their strongest design strengths.
After listening to the Oppo PM-1 Planar Magnetic Headphones with a variety of music, DACs, cables, amplifiers, and music players, we feel it is among the highest quality headphones we have ever listened to. From the exquisitely comfortable fit, to the variety of high-quality cables, ear pads, and accessories, to the uniformly superb fit and finish for every square-inch, the PM-1s are quite simply the best headphones we have ever used, headphones that grow better the longer you listen to them. Highly recommended!
Harris Fogel, with additional reporting by Nancy Burlan, posted 6/10/2014
For more information on the Oppo PM-1 Planar Magnetic Headphones visit: www.oppodigital.com
For more information on the Oppo HA-1 Headphone Amplifier visit: www.oppodigital.com
For more information on the Oppo BDP-105 Universal Blu-ray Disc Player visit:www.oppodigital.com
For more information on Beck on HD Tracks visit: www.hdtracks.com
For more information on Led Zeppelin on HD Tracks visit: www.hdtracks.com
For more information on the HD Tracks release of Van Morrison Moondance Deluxe Edition, visit:www.hdtracks.com
For more information on Chesky Records’ The Ultimate Headphone Demonstration Disc visit: www.hdtracks.com
For more information on Pure Music from Channel D visit: www.channld.com
For more information on Amarra visit: www.sonicstudio.com
For more information on Decibel visit: www.sbooth.org
For more information on the Audioengine D3 24-bit DAC, visit: www.audioengineusa.com
For more information on the Korg DS-DAC-100m visit: www.korg.com
For more information on the Cambridge Audio DacMagic XS visit: www.cambridgeaudio.com