Oppo Digital PM-3 closed-back planar magnetic headphones

Roughly two years ago Oppo Digital entered the high-performance headphone market in a powerful way. First came the firm’s flagship PM-1 planar magnetic headphone (favourably reviewed in Hi-Fi+ Issue 115 and Issue 116), which was followed by the cost-reduced PM-2 planar magnetic model (a model patterned directly after the PM-1), and finally there came the very affordable PM-3 closed-back planar magnetic model that is the subject of this review.

While there is an unmistakable family resemblance between these three headphones, the PM-3 distinguishes itself from its higher-end brethren in several important ways. First, it is the only compact, lightweight, closed-back model of the group and the only model explicitly developed with smartphone/tablet compatibility and portable applications in mind. Second, unlike Oppo’s PM-1 and PM-2 models, the PM-3 uses a circular planar magnetic driver (55mm in diameter) rather than the oblong (85mm x 65mm) driver featured in the upper end models. Finally, the PM-3 is priced at just £349, making it by far the least expensive model in Oppo’s headphone range and one of the most affordable planar magnetic headphones on today’s market.

Like all Oppo headphones, the PM-3 is the brainchild of designer Igor Levitsky (of BG Radia fame), whose credentials as a designer of planar magnetic drivers are impeccable. In a 2015 interview with Hi-Fi+, Levitsky spoke at some length about his headphone design priorities, stating, “Without a doubt, for a top-level headphone, sound quality is the most important. If we talk about a real life headphone, not just a lab device for short term comparative sessions, then the second top objective for me is to make sure it is enjoyable to use in real life conditions for prolonged periods of time. This is mostly related to comfort (weight, construction), ergonomics, and, to some extent, to industrial design, feel, and appearance.”

Levitsky also acknowledged that the PM-3 was at once one of his most challenging but also most satisfying design projects, observing that,

“We wanted PM-3 to be truly portable and affordable for a wide range of customers that would appreciate higher resolution quality sound… This was a very tough call. How were we to retain superior sound quality at a much lower cost while also providing high sensitivity combined with small weight? I hope you realise that all those factors are contradictory, especially for planar magnetic headphones.”

A brief technical overview of the PM-3 will help explain some of the steps taken by Levitsky in an effort to meet these design objectives.

The PM-3 is an elegant and deceptively compact headphone with a beautifully made, size-adjustable metal frame fitted with articulated (swivelling) metal yokes that hold the ear cup assemblies. By design, the yokes allow the ear cups to be turned sideways to fold flat, thus enabling the headphone to fit within a relatively compact travel case (included). At first glance, the PM-3s seem to be roughly the same size and shape as the upper-end PM-1 and PM-2 models, but in reality the PM-3 is significantly smaller and lighter (just 320g) than its bigger brothers.

The PM-3’s closed-back ear cups are made of a moulded thermoplastic material trimmed with brushed metal cover plates finished to match the chosen colour of the headphone (black, in the case of our review samples). Both the padded headband pad and ear cup pads are covered in protein leather, which looks luxurious and feels sumptuous to the touch. Apparent build quality is extremely high, especially in light of the PM-3’s moderate price. Unlike Oppo’s larger models, the PM-3 features just one signal cable connection jack, located on the bottom of the left ear cup. The PM-3 ships with a fairly heavily built 3m audio-only signal cable and with a much shorter and lighter 1.2m, smartphone cable supplied in the buyer’s choice of an Apple or Android-compatible version.

The PM-3 ear cups are fairly compact, but nevertheless will provide a comfortable though cosy over-the-ear fit for many listeners (myself included). However, listeners with larger ears might conceivably find the PM-3 to be more of a quasi-on-ear than an over-the-ear design.

Internally, the PM-3 planar magnetic drivers follow the same general design concepts applied in Oppo’s flagship models, but with various necessary adaptations appropriate to the PM-3’s role as a portable, closed-back headphone. Like the larger Oppos, the PM-3 planar magnetic driver features a seven-layer diaphragm with double-sided aluminium film conductors, plus a Neodymium magnet array developed through FEM (Finite Element Method) design. As mentioned above, though, the PM-3 driver is smaller than the PM-1 and PM-2 drivers and is circular rather than oblong in shape. The general idea was to have a driver smaller and lighter than the ones used in the flagship models, but that maintained the high sensitivity and nuanced sound quality for which Oppo headphones are known.

In our 2015 interview, Levitsky told Hi-Fi+ that the PM-3 had been voiced with bass levels, “elevated by about 5-6 dB from measured flat response to overcome the masking effect of noise when the listener is on the move or outdoors.” This voicing choice, said Levitsky, also addressed the fact that closed back headphones tend to have “higher acoustic output impedance” and are, “more prone to bass loss due to realistically imperfect fit.” Apart from judicious bass lift, the designer also, “carefully balanced the (PM-3’s) response to avoid excessive HF energy in the 3-to-5 kHz range that could easily lead to annoying sibilants and hardness on average pop music.” The point is that every aspect of the PM-3 sound was carefully weighed and judged in advanced, always with an eye toward creating an easy to drive portable headphone that preserved a serious measure of high-end sound quality and that offered what Levitsky terms, “realistic dynamic impact”.

I decided to test the PM-3 with the sorts of electronics for which it was designed. Accordingly, I did much of the listening for this review through a Samsung Android smartphone, an Apple iPad Air tablet, and through two very high-quality, high-res digital audio player; the Lotoo PAW Gold and the Questyle QP1r.

How did the PM-3s sound when put to the test? Several qualities stood out for me. First, the headphone delivered wonderfully extended, tightly focused, and decidedly impactful bass. A perfect example would be the recurrent low percussion and subterranean synth bass passages heard in Lorde’s “Royals” from Pure Heroine [Lava Music, CD]. On that track the PM-3s showed exemplary low frequency power, depth, and control—especially when reproducing the loud, low, and envelope-modulated sounds of the synth bass. Was the PM-3s somewhat elevated bass response noticeable? It was to a degree, at least in very quiet listening environments, though the PM-3’s superb bass control consistently kept the headphone from sounding loose, billowy, or overblown. More importantly, the PM-3s bass response curve enabled the headphone to pass the ‘listening in a noisy coffee shop’ test with flying colours, gracefully overcoming the distracting sounds of whirring coffee grinders, customer conversations, foot traffic, and so on.

Next, I was impressed by the PM-3’s agile, expressive, and for the most part neutrally voiced midrange. These qualities are readily apparent on “Touch of Trash” from Patricia Barber’s live album Companion [Premonition, CD], where the PM-3 did a lovely job of capturing Barber’s lilting and breathy-sounding voice, not to mention the rich and downright exotic-sound mix of accompanying keyboard and percussion instruments. Yet if this track serves to show one of the PM-3’s greatest strengths (namely, its gorgeous and highly articulate midrange), it also shows where certain sonic compromises have been made. Specifically, “Touch of Trash” shows how the PM-3’s upper midrange and lower treble response deliberately have been pulled back a bit—a design choice that makes the headphone more forgiving of mediocre records (and source components), but that also makes it sound slightly less open, airy, and spacious than would be ideal on good recordings. Personally, I thought the PM-3’s voicing choices made good sense, especially when listening through smartphones or tablets, which can otherwise impart an annoyingly bright or brittle sound.

Overall, I thought the PM-3 sounded more like Oppo’s flagship PM-1 than not: remarkable when you consider how much less expensive the PM-3 is relative to the top model. The PM-1 undeniably offers higher levels of resolution and serves up a more open, transparent, and neutrally balanced resentation, though the more compact and affordable PM-3 is not slouch in any of these areas. In fact, as you interact with the PM-3 and use it in a variety of listening contexts, you will inevitably come to appreciate its sheer versatility and the well-judged mixed of sonic and ergonomic virtues it offers—virtues that together make Oppo’s PM-3 a true ‘high-performance headphone for all seasons’.

TECHNICAL SPECIFICATIONS

• Type: Closed back, circumaural planar magnetic headphones
• Driver complement: Circular 55mm planar magnetic drivers with seven-layer diaphragms with spiral‑shaped conductor arrays on both sides of the diaphragm, and a ‘symmetric push-pull’ Neodymium magnet system
• Frequency response (in Free-Field): 10Hz – 50kHz
• Impedance: 26 Ohms
• Sensitivity: 102dB/mW
• Accessories: Selvedge denim carry case, 6.35mm stereo headphone adapter plug, and two sets of detachable signal cables: One 3m fabric-jacketed main cable terminated with a 3.5mm stereo mini-plug, and  Buyer’s choice of one of three available 1.2m portable cables: Cable with in-line Apple remote/mic module,
  Cable with in-line Android call answer button/mic module, or Cable without a mic module.
• Weight: 320 grams (without cables)
• Colour options: Black or white.
  (Note: Some international markets also offer options for blue and red versions.)
• Price: £349

Manufacturer: Oppo Digital

URL: www.oppodigital.com

UK Distributor: Oppo Digital UK, Ltd.
42 Hellesdon Park Road,
Norwich, Norfolk
United Kingdom NR6 5DR

URL: www.oppodigital.co.uk

Tel. (UK): 0345 060 9395

Tel. (Europe): 0044 345 060 9359 or 0044 1603 402240

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