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Thursday, July 17, 2014

Audiophile Headphone Review!
Oppo PM-1 Balanced Planar Magnetic:
Airy, Open Tone/Easy On the Ears

Price: $1,099
Likes: smooth response, comfy
Dislikes: Limited isolation
Wow Factor: "No fatigue here"

by John Gatski
  I received the Oppo HA-1 headphone amp and the PM-1 headphone at the same time. (Check out the separate Oppo HA-1 Review).
  The $1,099 PM-1 features a planar magnetic ribbon driver design in a compact, impressively lightweight frame with adjustable ear cups, and balanced or unbalanced operation. The key to the PM-1’s performance is the planar magnetic driver, which offers a smooth, even response — without peakiness in the treble. Planars also project a wide and deep sense of space that is perfect for headphone listening.
  Planar magnetic design has been around for about 40 years. It is basically ia hybrid design utilizing the principle of magnetic speaker speaker design and electromagnetic. Like a dynamic headphone — with their standard magnet drivers, planar magnetic headphones use a magnetic field that surrounds a conductor, which has an electrical current flowing through it to drive the speaker diaphragm.
  But the PM-1, like an electrostatic driver, utilizes a diaphragm of consisting of a thin sheet of flexible transparent film. Additionally, the PM differs from the electrostatic by using thin, flat electrical conductors to charge the diaphragm. Additionally, the Oppo PM-1‘s unique 7-layer diaphragm, double-sided spiraling coils, and an FEM-optimized magnet system enhances the headphone’s performance.
  Many audiophiles believe the contiguous diaphragm surface creates a more natural sound than standard dynamic drivers, and in recent years, companies such as HIFiMAN and Audieze have been part of the technology's resurgence.
  The PM-1 was designed by Igor Levitsky, a top-flight acoustical engineer who was involved on BG Radia's planar magnetic tower speakers and SLS ribbon loudspeakers. I met with an Oppo rep. and Levitsky last winter to audition the PM-1 and HA-1; I came away impressed with the pre-production headphone.

Hi-Res listening with PM-1, Android Phone and HA-1

  Unlike other planar magnetic HPs, the Oppo PM-1 is fairly lightweight — at 395 grams. Its lightweight aluminum frame features padded headband, adjustable ear pieces and removable able ear pads. Spec wise, the headphone are rated from 10 Hz to 50 kHz, though the usable range is in the 40 Hz to 20 kHz spectrum with a gradual roll-off in the high treble. Sensitivity is a very good 102 dB at 100mW. Maximum input power is 500mW continuous (2W pulse). The PM-1’s system impedance is 32 ohms, which is moderate in its ability to be driven. I found that most of my portable devices could drive the PM-1 to louder levels — if necessary.
  Oppo goes all out in its PM-1 packaging: a wooden storage box, a carrying pouch and extra ear pads. It also is available with an optional $79 headphone stand. To provide the most in listening flexibility, the headphone package sports a 2-meter unbalanced (optional 2- and 3-meter balanced cables are available, with OCC construction/Neutrik termination, at $129 and $149), as well as a shorter, small gauge, 1/8th-inch connector cable for portable devices. The detachable L-R cable ends plug in to their respective ear connectors.

The set up
  I put the PM-1 through its paces with numerous headphone-enabled audio gear including the Oppo HA-1 and other onboard HP amp-equipped audio devices: TASCAM DA-3000 recorder/player, TASCAM DR-100 Mk II hi-res portable, AK 100 portable hi-res player, Resonessence Concero HP DAC, Benchmark DAC2 D, Mytek Stereo 192 DSD DAC, and the Parasound Z-DAC/headphone amp. Headphone-only amps included the Benchmark H1 and the Bryston BHA-1, which also is balanced.
  Material ranged from well-recorded CDs to 24-bit and DSD hi-res sources. DAC-to-source interconnects were provided by WireWorld and power products, including power cords and strip, were courtesy of Essential Sound Products.

The audition
  Right off the bat, the PM-1’s sound was essential planar magnetic — a smooth, balanced, yet detailed tonal quality with just a hint of mid-bass rise. After a few days of break in with a CD on repeat (moderate level please; turning the HP amp wide open can destroy the drivers) the mid-bass bump was less noticeable.
  The first thing you notice about the PM-1 is how nice the ear pieces feel around the ears. The headphones definitely felt lighter than the HIFIMAN Reference HE-6 that I have auditioned, which weighs about 200 grams more. The PM-1 is quite comfortable —  without any focused pressure on my eyeglass arms. It also felt less bulky than my reference AKG K702s. Not quite as comfortable as the Shure SRH1840, but it is not that far off.
  With hi-res music, such as the Anthony Wilson Trio - Our Gang SACD, the warm jazz guitar/Hammond organ/drums, minimalist recording came shining though with its essential accuracy, including that wonderful space around the drum cymbals. The PM-1's top end is super smooth. Its signature, indeed, is similar to a quality ribbon speaker on the top end.

A perch for your PM-1: Oppo's $79 optional HP stand

  On the Gene Bertoncini — Body and Soul SACD, the transient response on Bertoncini’s guitar fingerpicking, was out in front with a nice spread in the L-R. The energetic percussion on the Flim and the BBs — Tricycle SACD was airy with solid extension on the top end as well. Unlike some ribbon speakers, I did not notice a major roll-off above 12 kHz-15 kHz.
  On all kinds of music, including Classical, Jazz and Pop, the PM-1 excelled in its delivery. These ‘phones are quite accurate, yet smooth, without the significant low treble and bass bumps, headphone companies often incorporate in their designs to get a more pronounced, “pleasing" tone that is often not accurate.
  The Oppo PM-1 is really clean from the high bass to the top-end — with that bit of boost in the midbass. To my ears, they just get out of the way and let me hear the recording. And of course because of the Oppo HA-1’s super headphone amp output, the PM-1 is a perfect mate for its electronic stablemate. The HA-1 ‘s extra clarity on the top end and well-spaced imaging, complements the PM-1's planar magnetic gradual roll-off character.
With hi-res music, such as the Anthony Wilson Trio - Our Gang SACD, the warm jazz guitar/Hammond organ/drums, minimalist recording came shining though with its essential accuracy, including that wonderful space around the drum cymbals. The PM-1's top end is super smooth.

  I did connect the PM-1 in the balanced mode, with the Oppo HA-1 and the Bryston BHA-1 headphone amps. Though some claim improved sonics via balanced HP connection, I could not hear any difference between the unbalanced or balanced from either headphone amp. Maybe the balanced gives you a little better SNR numbers, but, in my real world setup, it was not audible.
  The PM-1's sounded terrific on most any HP-equipped device. From a host of tested portable and DAC/HP amps, to home recording gear, the PM-1 never disappointed me. The PM-1 sound impressed my ears when using a multitude of portables: the Sony PCM-D100 handheld PCM/DSD recorder, the portable Astell and Kern AK100, the hi-res TASCAM DR-100 Mk II hi-res recorder  and my Android Dell tablet with Resonessence Concero HP. I had no problem driving the headphones with any of the portables.
  I even used the headphones for several recording sessions with the TASCAM DA-3000 master recorder. While tracking a direct-to-stereo DSD acoustic guitar session I appreciated its smooth, fatigue-free transient delivery and all-day comfort. Being an open phone, they do not seal out much external noise.
  I did not have any other planar magnetic HPs on hand for comparison, but in comparison to typical magnet driver 'phones, the PM-1's sound is balanced and accurate — with less emphasis in the treble. Similar to what I have heard in sessions with the top-end HIFIMAN planar magnetic models, but the Oppo is more commfortable, at least on my ears.
  Withs its satisfying performance assured, the Oppo’ PM-1‘s packaging is just icing on the cake. The optional headphone stand enables easy access and a classy display of these premium 'phones; the wood storage box gives you a nice place to pack them away. After all, the PM-1 cost more than a grand. They deserve the royal treatment. The optional balanced cable and the standard unbalanced cable are made with a light cloth wrap, which exudes a high-end look and feel. 

The verdict
  All in all, Oppo did a great job with its inaugural headphone, the PM-1. It is not cheap, but in the high-end audiophile world, its price is reasonable, given its quality build and top-notch sonic performance. And Oppo goes out its way to give you extras for your money (a nice storage box, carrying case, 3-meter unbalanced cable and extra ear pads). If you are into ribbon-style headphones or just want an musical set of cans, regardless of the design technology, the Oppo PM-1 deserves a listen. A big ole Stellar Sound Award!!

 John Gatski is publisher/owner of the Everything Audio NetworkArticles on this site are the copyright of the ©Everything Audio NetworkAny unauthorized use, via print or Internet, without written permission is prohibited.

1 comment:

meghanhoward said...

Nice review! A bit pricey for me.. I have other headphones alternative considering the price, audio quality, build quality and comfort like Grado SR80i and Audio Technica ATH-M50.