August 2014


Oppo PM-1 Planar Magnetic Headphones
Not only a great planar magnetic headphone, but a great headphone, period.
Review By Tom Lyle

  If any company deserves to be acknowledged for promoting the high-end at low prices, especially within the past decade, it should be Oppo. Enjoy the Music.com's review here with the Oppo PM-1 planar magnetic headphone is but one example of many. Their $169 DV-980HD and DV-981HD universal disc players released in 2007 and 2008 are considered by many benchmarks for budget players. They are both ridiculously good for their ridiculously low asking prices. As the network effect gathered steam these budget audio/video products ended up in the systems of both audiophiles and regular citizens alike. I still have a '980, and yes, it works just fine – I use it every now and then in my second system. Since 2010 I have also been using an Oppo BDP-83 Special Edition universal player. It cost $899 when it was new; it can play Blue-ray discs along with any other 5" silver disc anyone could think of. I use it in my main system to play the occasional SACD and DVD-A. Its sound quality might not be the best that the high-end has to offer, but its price to performance ratio is mind-blowing -- it easily outperforms many current offerings costing much, much more. Let's get right to the my review of Oppo's PM-1 planar magnetic headphones.

Most will not consider Oppo’s $1099 PM-1 headphones inexpensive. However, what set Oppo’s $1099 PM-1 headphones apart from most others are its planar magnetic drivers. Also setting the PM-1 apart from the others is that Oppo’s planar magnetic headphone costs much less than other brands using this driver technology. Compared to the ubiquitous cone-shaped dynamic driver the thin, light, and flat planar magnetic covers much more surface area, and its pull-push mechanism is more sensitive and has greater consistency than a "normal" dynamic driver. The very stable and linear piston-like vibrations that emanate from the planar magnetic diver of the Oppo headphone is also more phase coherent, has excellent resolving power, and also generates less distortion. The type of planar magnetic driver used in the PM-1 is unique because it is double-sided. This allows Oppo to put twice as many conductors within the magnetic field, and also eliminate any "passive return zones", which are areas where the conductors have no effect. This enables the entire surface of the driver to be used, which increases efficiency. Its flat conductor also reduces distortion to vanishingly low levels, and Oppo claims that its "purely resistive impedance" enables it to be used with a wide variety of sources since the amplifier’s output impedance is rendered meaningless. This means that a headphone amplifier isn’t mandatory in order to drive the PM-1s to a reasonable level (even though most audiophiles will still likely take advantage of the benefits that a headphone amplifier will bring to the listening experience).

The fit-and-finish of PM-1 appears to be second to none, and in the headphones' carton are two types of ear-cushions, leather and velour, that are easy to swap, simply by pulling the old ones out and lining up the pegs on the new. Since the audition period was during the hottest months of the summer I preferred the velour ear cushions as the leather made me feel a bit too warm. The earpieces rotate so the 'phones can be laid flat to store in the provided denim storage bag. The PM-1 comes with two different cables – a longer cable with a ¼" plug on its end, and a shorter one for when listening to portable devices that are terminated with a 1/8" mini-plug. As an option one may purchase a cable terminated with an XLR plug, which makes sense if pairing these headphones with Oppo’s HA-1 headphone amplifier that is a balanced design fitted with an XLR headphone input in addition to its RCAs.

Packaging
The Oppo PM-1 comes packaged quite lavishly in a polished wooden box, and will likely join the ranks of popular electronics products with an "Unboxing" video on YouTube. Go ahead and take a look if you don’t mind watching others indulge in this banal activity, but it does give one a sense of how Oppo went out of their way to impress with their relatively opulent packaging. However, I’m sure readers of Enjoy The Music are more interested in the sound quality of the PM-1 more than anything else. During the time I auditioned the PM-1 I was lucky enough to have more than a few headphone amplifiers on hand – an older Headroom model, the Pro-Ject Headbox DS, and an M2Tech Marley among others, but most notably -- Oppo's new Class A balanced HA-1. Even though I used every one of these headphone amplifiers during the review period, the Oppo HA-1 is the one I used the majority of the time during the PM-1’s review period, more often than not using the PM-1’s optional XLR terminated cable. It’s a safe bet that more than a few will at the very least consider purchasing the PM-1 headphone and the HA-1 together, and it should be a surprise to no one that I found there to be a synergistic relationship between the two.

The HA-1 is a very impressive headphone amplifier. Not only is it a balanced design, but it contains an on-board digital-to-analog converter (DAC) that rivals the sound quality and features of units costing as much or more than the HA-1. The HA-1 has enough gain so it can be used as a system’s preamplifier, but it also contains not only both a balanced XLR and single-ended RCA analog inputs, but five digital inputs including an asynchronous USB port that converts digital signals up to 32-bit/384 kHz and DSD256. The unit is compatible with iPod/iPhone/iPad and Bluetooth, and in home theater bypass mode the pre-amp output level are fixed and can be used as a tape output. The HA-1 is the first headphone amp that I ever reviewed that I can state without reservation that can be used as one’s dedicated preamplifier in a modest high-end system. It compares favorably to many preamplifiers that cost as much or perhaps even more than the HA-1, but as a bonus the HA-1 also includes a killer headphone amp section and fantastic DAC. When used as "just" a headphone amp, the HA-1’s cabinet might be more than a bit larger than some would prefer, but I can’t image any owner of the HA-1 not being forgiving of its size, as it is a top-flight headphone amp/DAC/preamplifier that Oppo is selling at a very reasonable price.

The high-quality Oppo PM-1 deserves an outboard headphone amplifier, so that’s how I listened to it the majority of the time. It is sensitive enough to connect directly to a mobile devise, so I never had to turn the volume to a ridiculous level, draining my battery to achieve a normal volume, even in a noisy setting.  But the PM-1 is also sensitive enough to reflect the quality of signal it's being fed, so it sounds much better with the highest quality headphone amplifier I had available, in this case the Oppo HA-1. Connected to the headphone amp was either my main system or a mobile device. My mobile device of choice is a 160 gigabyte iPod Classic. Unfortunately, or simply just a sign of the times, these devices are going out of style in favor of listening to music on one’s mobile phone. I know many an audiophile that couldn’t do without the Classic iPod as it has enough memory so that compressed audio can be avoided. I believe about 98% of the music on my iPod is non-lossy AIFF, which is indistinguishable from the uncompressed signal from which it was created. I prefer quality over quantity, and so my iPod allows me to indulge in this. I also bypass both the iPod’s internal DAC and audio section with the inexpensive (less than $100) Pure i-20 iPod/iPhone dock that has an internal DAC (which I haven’t yet auditioned), an analog RCA output and a coaxial digital output. I connected the coax output to the Oppo HA-1’s coax input using an MIT digital cable. In my main system I’m currently using a Balanced Audio Technology (BAT) VK-33 preamplifier (a review is coming soon) that has a tape output via RCA, so a long run of interconnect sends an analog signal to the analog input of the HA-1 or other headphone amp I’m using at the time. When using the main system the sound is undoubtable better, but the ease and convenience of using the iPod is hard to resist! And it’s much easier to rationalize since I’m using un-compressed signal and bypassing the internal DAC/amplifier of the unit.

The Oppo PM-1 headphones weigh much less and are much more comfortable than the Grados, the top headphone in my arsenal. They are much closer in weight to the rebuilt Sennheiser SR-600s I’ve been using for more than a decade. The Sennheisers are famous for their level of comfort, but the Oppo comes very close -- close enough to where I would call it almost a tie as to which one I prefer for lengthy listening sessions. This is high praise, indeed. I was able to listen to the PM-1s for hours on end without being annoyed by their presence, and best of all, the sound of these 'phones never became fatiguing. But more on that soon. Although it was not its most salient trait, my first reaction in regards to the sound quality of the Oppo PM-1 was that they sounded "bigger" than my other headphones, which makes sense since the larger surface that planar magnetic drivers cover versus the dynamic drivers of the other 'phones. Even though this characteristic was a positive one, it took some getting used to.

Bear with me for a moment while I discuss the rather odd soundfield presentation of music with headphones that we all know and love. Even the best headphones on the market cannot – and do not seem to bother trying to – reproduce a soundstage that mimics a real life situation. The best headphones that I’ve heard have a soundstage, or whatever term one wants to use for the soundfield that emanates between the two drivers of a pair of headphones, that seems to emanate from outside the confines of the headphone’s earpieces. This at least produces images of instruments and voices that seem to originate outside of one’s head. This trait aids in separating instruments and voices from one another, and also leads to a more "realistic" reproduction of instruments and voices. With the dynamic driver Grado PS-1000, when a solo voice or instrument is centered between the two channels often it appears just in front of my forehead. Lesser headphones will produce an image inside my skull. The majority of good high-end headphones – which includes the PM-1’s – reproduce some individual instruments and groups of instruments in a soundfield that sometimes generate an aura of sound around one’s head.

Although the soundstage of the planar magnetic PM-1 has a different character than the dynamic driver, as most of its sounds are located closer to the outer circumference of the headphones themselves, and the images, if I’m allowed to use this term, are predominantly spread across the area of the surface of the large driver. High quality headphones using dynamic drivers, such as the Grado, are champs at producing many "suspension of disbelief" moments -- where very realistic sounds occasionally emanate from far outside the confines of the headphones. The Oppo 'phones don’t have as many of these moments as compared to the top-flight Grados, but compared to any similarly price headphones using dynamic drivers the larger surface of the planar magnetic driver creates more discrete lifelike sounding images throughout the man-made soundfield, that again, some call a headphone’s soundstage. This feature allows enough separation between individual instruments and voices and increases the number of sounds with a realistic semblance. Although it might seem as if I’m being a bit obtuse in my description of the planar magnetic characteristics versus the dynamic driver, this is most likely due to lifetime of listening to dynamic drivers, and now with the Oppo I am now hearing a very different type of presentation. This is certainly not a bad thing, it is just different. And it is quite magnificent, really, as the end result is a set of headphones that immerse the listener with some very realistic sounds with a larger aural perspective.

Lately I’ve been on a Todd Rundgren kick. This might be due to the fact that I purchased Rundgren vinyl reissues on Friday Music, his 1973 landmark album A Wizard, A True Star, and the follow-up Todd. I was disappointed with Todd; my original copy on Bearsville/Warner Bros. is much better in just about every way, despite its rather noisy surfaces due to about a zillion plays. Luckily, A Wizard, A True Star is a considerable improvement over the original simply because Friday Music made the wise decision to spread the music onto two discs instead of one, belatedly atoning for Todd Rundgren's sin of attempting to squeeze over thirty minutes of music onto each side of the original album, decreasing its volume along with every other sonic quality that makes recorded music sound good. The CD pressing isn’t bad, but this new vinyl reissue is much better. Regardless if one listeners to the CD or the new LP, this is a great album to listen to through headphones. The multi-track wizardry (sorry) of Todd Rundgren finds him not only filling up every track with all sorts of voices, sound-effects and instruments, but he also manages to shape the album into an shape-shifting hallucinatory but very melodic pseudo-concept album using every rock 'n’ roll  instrumental technique along with tin pan alley singer-songwriter versification and a sense of humor. Whew.

Even without knowing the source of many of the sounds on the album – no doubt due to a combination of what we now call "vintage" analog synthesizers and tape manipulation – he sculpts this album into an experience that begs for one to sit down and follow his narrative as closely as possible. He bookends the first side of the original LP with "International Feel" (he titles its reprise "Le Feel Internacionale") filling the LP side with everything but the kitchen sink, with many songs lasting only a little more than a minute including the number from Peter Pan "Never Never Land", along with a potpourri of moods and styles, all sounding like prototypical mid-period Todd Rundgren. The Oppo PM-1 headphones let it all wash over me, not missing one iota of detail, but at the same time letting me appreciate the analog warmth that bathed the entire affair.  Simmering beneath the onslaught of sounds are often the bubbling synthesizers, along with a host of overdubs and vocal harmonies, inside musical jokes and flourishes, much of it lost on the original LP version. Although the PM-1 exposes every fragment of sound, at the same time the combination of planar magnetic realism and smoothness manages to make it so the music never, ever becomes fatiguing. Neither does it get boring, thanks to Todd Rundgren, of course, but also because the PM-1 renders the individual sounds, natural, man-made and somewhere in between, much of the time with a 3-D, reach-out-and-touch palpability.

Due to the larger surface area of the planar magnetic driver the sounds on this LP are literally farther away from each other. The sonic gift of the PM-1 is that it allows one to revel in the details of the recording, yet it does not sound analytical. It permits these sounds to be heard because of the driver’s innate naturalness, and therefore if the sounds are present they are going to be heard. Yes, it’s as simple as that.  Side two of the album is more straight ahead, he even takes time out for a soul medley, but just to prove that he hasn’t "mellowed out", it ends with "Just One Victory", a thematic closer if there ever was one, as Mr. Rundgren attempts to once again bury the melody underneath a thicket of overdubs. The PM-1 rises to the challenge once more, letting one realize that Todd Rundgren is indeed not only one of the best songwriters of the mid-70s, but also knows his way around a mixing console. Yes, on the original album all of this ends up sounding like a mess, but perhaps he predicted that the technology would eventually catch up with him, so one day we would be able to untangle the genius this is buried beneath the din. The PM-1 not only unravels it all, but somehow places each instrument and voice in a multi-layered, enormous soundfield for all to enjoy. What a ride.

Lest one think that I only listened to rock 'n’ roll through the Oppo PM-1, I also spent many an evening listening to classical and jazz, in other words listening to albums that featured real instruments and voices recorded in a real space. I love it when people label a composition a "warhorse". In popular music when a piece of music is loved by many and played again and again it is called a "hit". I really don’t need a reason to listen to Beethoven’s Third Symphony ("Eroica") over and over again. If one is going to obsess over a piece of music one could do much worse than this! I suppose it is reflective of my personality because lately my favorite movement of this symphony is the second, one that Beethoven entitled "Funeral March". I’m not as concerned with the musicologists interpretations in regards to the personal crisis the composer may or may not have been undergoing when he wrote this movement, I’m more concerned with the music itself and the compositional genius that unwinds during the course of the movement, and the brilliance of the composer’s orchestration that has kept this movement and the entire symphony in the repertoire for over two hundred years. During the audition period regardless if I was playing an LP of the version by Charles Munch and the Boston Symphony on RCA recorded in the late 1950s, an SACD of slightly later version by Deutsch Grammophon by Herbert Von Karajan with his Berlin Phil, or even a plain-vanilla budget CD of David Zinman with the Zurich Tonhalle they all had one thing in common – the Oppo PM-1’s ability to draw me into these different interpretations of one of the best works that has ever composed. When the oboe enters at the beginning of the movement in a near perfect musical expression of mourning and sorrow, the PM-1 allows me to hear the air around the instrument, the ambience of that particular stage and the hall, the breath of the musician the split second before the note starts, and style of the oboist on that particular recording, as it all comes together in that one defining moment. A great pair of headphones can do that. The Oppo PM-1 is a great pair of headphones. Added to this, of course, is the ability of the PM-1 that I mentioned above to separate the instruments and groups of instruments, allowing them to occupy distinct areas in the soundfield that can envelop one’s head.

When one makes an allusion to planar magnetic speakers most often this will bring to mind Magnepan loudspeakers. Although Magnepan markets their speakers as "magnetic/planar", I assume this is the same technology behind the Oppo PM-1 headphones. I owned a pair of Magnapans for a while in the early 1990s so I am very familiar with their sound. Even though they use what I assume is very similar driver technology, and even if it is not, it is a bit of a stretch to compare the sound of a full sized Magnapan to the Oppo PM-1. The scale is too disparate.  In any case, there are two qualities they have in common; the first is their attenuation at the frequency extremes. The good news is that this trait isn’t nearly as noticeable when listening to the PM-1 as it is when playing material through a pair of Maggies. But it is audible, and manifests itself as a slight rounding off of the highest and the lowest bass. As a consequence, the sound of the PM-1 leans somewhat more to the yang than to the yin. The other trait I already cited is positive, the larger surface area of the planar magnetic driver compared to the average driver used in most headphones. This tradeoff is one that many are willing to make with Magnapan speakers, as it is with the PM-1 -- the combination of the slightly more mellow sound of the headphones combined with the large surface area of the driver makes for some very pleasurable listening sessions.

Everyone
As with all audio products, the Oppo PM-1 isn’t meant for everyone. The PM-1’s planar magnetic driver has a sonic presentation quite unlike the vast majority of headphones that use the more common dynamic driver. Its slightly rounded off transients and somewhat reserved frequency extremes will be more noticeable to some than others. This results in a slightly warmer sound that takes some time to get used to, but becoming accustomed to this sound is not very difficult because in exchange for these minor imperfections is a sound that is lifelike, and quite faithful to the source. Sounds emanate from a driver surface area that is larger than most listeners have ever experienced, enveloping not only one’s ears with sound, but one’s senses.

The Oppo PM-1 is not inexpensive. Many will not be able to afford them – non-audiophiles will surely balk at their price. Even the PM-2 which Oppo will soon to bring to market that will probably sell for around $700 might be a stretch, even for those considering an upgrade from a set of mass-market designer headphones. After hearing the Oppo PM-1 there will surely be audiophiles that will view their $1100 price and consider them a bargain, not only because a speaker system with the sonic credentials of these headphones would cost thousands, perhaps even tens of thousands of dollars, but because the Oppo PM-1 is a bargain when compared to other headphones built with the similar technological features, and especially when compared to other headphones with a comparable level of sonic features. My listening test revealed that the PM-1 is not only a great planar magnetic headphone, but a great headphone, period. Recommended? Are you kidding me?

Ratings: (Please keep in mind that my ratings are similar to stars in restaurant reviews. 5 notes - the best I’ve ever heard, 4 - extraordinary, 3 - excellent, 2 - very good, 1 - good, 0 - poor to satisfactory).

Specifications
Type: Planar magnetic stereo headphone
Driver
Driver Type: Planar magnetic
Driver Size (Oval): 85 x 69 mm
Magnet System: Symmetric push-pull neodymium
Frequency Response: 10 Hz to 50 kHz
Long-Term Max Input Power: 500 mW
Pulse Max Input Power: 2 Watts
Headphone
Acoustic Principle: Open back
Ear Coupling: Circumaural
Nominal Impedance: 32 Ohm 
Sensitivity: 102 dB in 1 mW
Clamping Pressure: 5 N
Cables: 3m detachable OCC cable (6.35 mm), 1m detachable OFC cable (3.5mm) 
Cable Connectors: Output: 2.5 mm mono mini jacks, Input: 6.35 mm stereo jack, 3.5 mm stereo jack 
Weight: 395 g (without cable)
Included Accessories: Wooden box, carrying case, 6.35 mm and 3.5 mm cables, alternative set of velour pads, user manual.
Price: $1099

Company Information
Oppo Digital
2629 Terminal Blvd., Ste B
Mountain View, CA 94043

Voice: (650) 961-1118
Website: www.OppoDigital.com