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Oppo PM-1 Planar Magnetic headphones review (Part 2)

  • [Part 1 of this review can be read here. – Ed]

    Before my loaner pair had concluded its short trip from the UK, I’d done some basic online recon. For comparative context beyond what I’d have on hand, CNet’s audiophiliac Steve Guttenberg had already found that “…the AKG K812 ($1’500) did an even better job producing out-of-the-head imaging effects but the PM-1 trounced the K812’s low bass oomph. The PM-1 reached further down into the bass so it let me feel more of the score’s pulsing beats that kept up the film’s suspense.” For a comparison I’d make myself, Steve felt that the Audeze LCD-2 “…had a brighter overall balance and the treble was airier and clearer. The PM-1 was richer with a slightly warmer and fuller midrange – so much so that the PM-1 sounded like it was hooked up to a tube amp with my 100% solid-state Burson HA160 amp.”

    Brent Butterworth of who used HifiMan HE-500 and Audeze LCD-3 comparators called out the Oppo as giving “a lot more bass” that was “a little fatter and not quite as ‘stop-on-a-dime’ precise” but had “the more natural-sounding level”. Triangulating both reviews, I expected an absolute bass monster with a dark/warm overall balance. Because that’s how I’d describe my v2 LCD-2. Except that Steve had found the PM-1 to be darker still whilst Brent had called it far more bass potent than the LCD-3 which in my estimation does trail the LCD-2 but not by much. Given Oppo’s late-to-the-party advantages, such a result was not exactly what I’d anticipated. To be frank, I’d probably think of anything with more bass than the LCD-2 as faintly grotesque and anything darker than its treble balance as quite hooded. Was that really in store for my own encounter – sonic misfires?


    Paul at Hifi Lounge had also done the LCD2/LCD3 tango for three. He opined that “compared to the LCD-2 the PM-1 are more open and detailed and a little smoother at the very top end if not quite as organic. If I’m really honest they perform closer to the LCD-3 than the LCD-2.” That was more like it. For some gumshoe action I fired off a short questionnaire to Oppo UK managing director Nigel Rich and technical officer James Soanes. I wanted to know what strengths and weaknesses of the planarmagnetic approach they’d identified and how they’d gone about maximizing the good and solving the bad; what tech suppliers had contributed to their 7-layer diaphragm and what the particular benefits were of each layer; how they’d managed to shed weight despite a push/pull magnet array; which particular target response curve they’d aimed for; how they’d addressed reliability and consistency challenges; where the PM-1 were manufactured; and how an organization of their size goes about such a blank-slate project and assembles a technical dream team; who had been part of the team; and some juicy details on R&D stages, rejects, dead ends, final modifications, beta testing and such.

    I didn’t expect answers on it all. IP must be protected. But what’s answered and what’s not can paint its own picture. And the convoluted infrastructures of very big companies can even mean one gets no answers at all. Yet I was hopeful. After confirming shipment dispatch and following up with a DPD tracker, I’d asked Adam in their warehouse who my internal contacts for tech and company background were. He’d promptly furnished the above two names with their direct emails for a splendid start. Very professional. Would his brass follow through?

    Meanwhile I’d dug out published sensitivity specs for competing planars. At a crushingly low 83.5dB, HifiMan’s HE-6 sat at the very bottom of this pile followed closely by the Abyss AB-1266 at 85dB. HifiMan’s HE-500 upped this song and dance to 89dB. Dan Clark’s re-engineered Fostex called AlphaDog hit 90dB. Audeze hadn’t even entered this scene with anything less than that for their original LCD-2. The LCD-3 had then clawed up by one to make  91dB whilst HifiMan’s HE-400 did it one better at 92.5dB. Things efficiency got truly serious when Audeze rethought the subject with their later X models. Those hit 95dB and 96dB for closed and open-backed respectively. But at 102dB Oppo had knocked the sensitivity ball way out of the park. This suggested some very serious engineering to outrun established makers by such a margin. As technical advisor, Igor Levitsky’s familiarity with ribbon drivers from his work at Bohlender-Graebener had clearly paid off. Oppo’s take on planar tech had overcome one of its biggest handicaps.

    In general Igor prefers planar to dynamic drivers for their superior microdynamic detail recovery. This he relates to their absence of a high-inductance cylindrical voice coil. Near zero-inductance and purely resistive flat membranes use flat circuit traces imprinted with conductive ink for very low moving mass and linear impedance. As a result they don’t “smear and mask fine low-level musical details”. They also are capable of “responding faster to the signal attack and more accurately track short-term impulse sounds” to be “unequalled for percussive and string sounds”.


    Where the PM-1 does even its planar kin one better is to fold up flat with its 90° ear-cup swivels. Though you’re not likely to wear something this fancy, big and dear on the tube or your local fitness club’s exercise bike, frequent travelers wishing to luxuriate in sound once in their hotel rooms can pack these conveniently in the included black denim bag. And you certainly could and should wear these on your porch, patio or balcony for tunes plus views or at least some fresh air and rays. On upscale looks, opulent finish, wear comfort, storing convenience and ease of drive to welcome top portables, Oppo had obviously attended to their self-assigned home work with diligence (a balanced cable to take advantage of the HA-1’s fully differential circuitry will be an option).

    But reader Chris Skelton just couldn’t say amen to their math which he verbatim called “taking the piss out of the UK”. You see, the PM-1 reaches a US punter for $1099 whilst his UK mate shells out £1099. Before you shrug so what, realise how at writing day’s effective exchange rate this meant the English were billed a whopping $1845 in US currency or $1988 in Aussie dollars. That’s how quickly opportunity can turn opposition. Of course it’s not something reviewers have any say in.

    With the PM-1 unpeeled from its deluxe high-gloss Cherry presentation box to impress my eyes and fingers for full tactile confirmation of all the Photoshop perfection the stock hero shots had already given off—cue up geeky uuuhs and aaahs–I jacked in the shorter 3.5mm ‘portable’ leash once I’d made out the black-on-black channel identifiers. For my first test before I’d run up the recommended 100 hours, I wanted to check on achievable SPL on the go. With an Anna Maria Jopek cut from her Bosa album, my Astell&Kern AK100 sat at 54 on the dial of a possible 75. On some compressed Arab Pop compliments of Asala Nasri, I moved below 50. On Weber’s Clarinet Concerto N° 1 in F-minor played by Swiss reedman Fabio Di Casola, I moved up to 65 to account for the lower median level when proper dynamic range is on the recording.


    For my ears and loudness needs, A&K + Oppo had enough headroom for all occasions, i.e. all types of genres and their mastering standards. Bit by the apple, I mostly sat just below or at full max. With my last-gen 160GB Classic iPod, headbangers would surely be left wanting. Go Beats. Normies should be just about okay though. Using little or no attenuation when the digital domain is involved is actually an advantage. To cross off this item, a planar doing the solo deed with an Apple was a record. Anything with a higher useful output voltage than an iPod should be unconditionally fair game. Impressive! So was the fact that my wife had to move in real close and personal and I crank up the juice before she perceived any sound leakage at all. Where others are concerned, the PM-1 acts nearly sealed if you listen at civilized levels. Time to let break-in run its course…

    Associated equipment

    • System1: Quad-core 27” iMac (256GB SSD, 2TB hard drive, 16GB RAM) with PureMusic 1.89g in 176.4kHz NOS upsampler and memory play modes, SOtM 2-box battery-powered super-clock USB bridge, Metrum Hex, April Music Stello HP100MkII, Questyle CMA800R
    • System2 : 160GB Apple iPod Classic (AIFF), Pro-Ject iPod dock, RWA-modified Astell&Kern AK100 (ALAC), Aqua Hifi La Voce DAC, Bakoon AMP-12R, AURALiC Gemini 2000
    • System3: Windows 7 64-bit HP Z230 work station with JPlay’s alternate version, Spotify Premium (320kbps streaming), Qobuz Hifi (FLAC streaming), Aura Note V2
    • Headphones for all systems: Audeze LCD-2, LCD-XC; HifiMan HE-500, HE-6; beyerdynamic T5p recabled by ALO; MrSpeakers Alpha Dog; Sennheiser HD800 recabled by ALO
    • Cables: Light Harmonic LightSpeed USB cable, KingRex uArt double-header red, Zu Event power cords and interconnects, Vibex Three 11R power conditioner, Furutech eTP6 power bar

    Audition music

    • Mercan Dede “Su”, “800″, “Dünya”
    • Adnan Joubran “Borders Behind”
    • Sœur Marie Keyrouz “Méditations d’Orient
    • iLenKa “iLenKa“
    • Joana Jiménez “Joana Jiménez“
    • Tord Gustavsen Quartet “Extended Circle”
    • Rodolfo Mederos & Miguel Poveda “Diálogos”
    • Karim Baggili “Kali City“
    • Aytac Dogan “Deva”
    • Angelo Debarre & Marius Apostol “Gipsy Unity“
    • Sabine Meyer Bläserensemble “Antonin Dvorak’s Serenade in D-minor op.44”
    • Carel Kraayenhof “Guardians Of The Clouds“


    Further information:  Oppo UK | OPPO Digital | Oppo Digital Australia

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    Written by Srajan

    Srajan is the owner and publisher of 6moons. He used to play clarinet at the conservatory. Later he worked in audio retail, then marketing for three different hifi manufacturers. Writing about hifi and music came next, then launching his own mag. Today he lives with his wife Ivette and Chai the Bengal cat in a tiny village overlooking the estuary of Ireland’s Shannon river at County Clare’s border with County Kerry. Srajan derives his income from the ad revenues of 6moons but contributes to Darko.Audio pro bono.

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