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Oppo PM-1 Use and Listening Tests

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One of the advantages of planar over electrostatic drivers is low power requirements. Because the planar driver presents a purely resistive load, there are no wild impedance swings across the frequency response (as we'd see with dynamic drivers). They also don't have the low impedance and high power requirements we see with electrostatic drivers. So, if your amp has the voltage to drive the planar driver at one frequency, it should do fine at all frequencies.

oppo_pm-1_box4

Nope, no cigars, nothing but high-quality headphones here

The PM-1s are rated at 32 ohms with a 102dB sensitivity (1 mW). This is not an extremely hard load to drive for most devices and I had no problems powering the Oppos with my phone, other portable devices, and the headphone output of my laptop. From the standpoint of the end user, this can be seen as a benefit or curse. If you haven't bought a headphone amp, you don't necessarily need one. But if you have, and you spent a bunch of money on it, you may feel like you've wasted your hard-earned dough.

Don't. The Oppos will love all that power.

I used the PM-1 headphones almost exclusively with the Emotiva Stealth DC-1 headphone amp and DAC. The Emotiva is a standalone DAC and headphone amp that I run in purely asynchronous mode. This completely eliminates any jitter issues. I paired the Emotiva with my highest quality music, which is encoded at 24-bit and up to 192 kHz. Since it has 3.5mm outputs, I had to use Oppos one-meter cable. To actually reach the Emotiva, I paired that short cable with an extender I had lying around. For those that have just purchased a $1100 pair of headphones, pairing them with an extender seems almost sacrilegious. You'll also want to be careful about the extender you use since I found, after some testing, that one of my extenders negatively affected imaging.

oppo_pm-1_earcups-leather

Leather Earpads

I tried out both the different earpads (leather and velour) and found the sound remarkably different. The leather had a more open sound and definitely had more high-end extension. The velour pads seemed more subdued and warmer with a more laid-back high-end. At first I thought my mind was playing tricks on me. Later, I examined the back of the earpads and found that the velour material was extended into the opening of the earpad. Compared to the leather, the velour covered about half the opening. This seemed to deaden the high-end frequency response and give an overall warmer sound to the presentation. Later I found out that both the headphones were supposed to have the additional velour extending into the opening of the earpad. I preferred the sound of the PM-1s without the additional material.

Warmer is also how I'd describe the experience of wearing the velour earpads. The material didn't breath as well and was physically hotter than the leather. Personally, I preferred both the comfort and the sound characteristics of the leather. Having an earpad that physically EQs the sound was an interesting choice by Oppo and one that I haven't seen before.

oppo_pm-1_earcups-velour

Velour Earpads

 

With an open-back headphone, you are always worried about sound leakage. As I mentioned, the sound from outside the headphones wasn't nearly as pronounced as I expected. You could, however, hear the headphones from across a quiet room. Letting exterior sounds in was also an issue though not an unexpected one. I've had my parents living with me for the last few weeks as they look for a home in the area. I couldn't follow their conversations while l listened at a comfortable volume, though I could certainly hear that they were talking and found it to be very distracting. If you are looking into open-back headphones, you'll want to make sure you have a quiet location to use them.

Listening Tests

While the Oppo PM-1 Planar headphones could be driven easily by all of my devices, I definitely felt they sounded the best with the Emotiva Stealth DC-1. Pairing it with some high quality 24-bit tracks certainly allowed the PM-1 headphones to sing. I found, from a power standpoint, that the PM-1s could take up to 5dB more power from the DC-1. Part of that was that they just required more power. When I tried to A/B the PM-1 with other headphones (the DC-1 has two outputs), the volume differences were pretty dramatic.

oppo_pm-1_box5

oppo_pm-1_box6     oppo_pm-1_box7

Also dramatic - this box

But I found, over time, that it wasn't just that the PM-1s were power hungry. Instead, the sound was so clear and undistorted that I could turn them up louder without running into issues for driver breakup or fatigue. This clarity of sound was most evident in the midrange. The Oppo PM-1s midrange was so dramatically better than my other headphones that it was like comparing a Honda to a Ferrari. Sure, they are both cars, but you didn't need to be a car expert to tell that one had a performance advantage over the other. 

Vocalists in general and female vocalists specifically sounded much more forward and much more "in the room" than with other headphones. The result was a presentation that made it feel as if the vocalist was directly in front of you. The PM-1 headphones had more of an "inside your head" feel than other headphones I've experienced but not one that was distracting. The soundstage was wide but not as holographic as I expected. I thought with a planar driver, I'd have more of front and back movement in the soundstage but the PM'1s performed similarly to other headphones. This wasn't as much a knock against them as it was an adjustment of my expectations.

oppo_pm-1_case1

oppo_pm-1_case2     oppo_pm-1_case3

Less dramatic - this case

The bass response on the PM-1s was phenomenal. For the first time in all my headphone experience, I heard music down to 20Hz. Not noise, which is what most headphones produce in the bass region, but actual music. Not only was the bass response well extended, but also it was absolutely even as I flipped through the test tones. Sweeps from the bottom of the range up to the top maintained a subjective uniform volume level that I have never experienced. With tracks like Crazy from Seal, Junior B from Yello, and more, I heard bass as extended and clear as any headphone I've tested.

The top end of the frequency response is, traditionally, a sticking point for planar drivers. Subjectively, I liked the top end of the PM-1s. I put on Electric Counterpoint Version for Percussion - III by KUNIKO (96kHz/24-bit). This track features nothing but xylophone and a few other percussive instruments. Usually, the extreme top end of this track quickly becomes fatiguing after a few minutes on lesser headphones as the drivers distort or clip. Not so with the PM-1s. I could listen all the way through without feeling like the high notes were grating or piercing. Subjectively, I thought the top end of the PM-1s was a little rolled off. The notes that were there, however, sounded fantastic.

oppo_pm-1_slide     oppo_pm-1_swivel

Oppo PM-1 Slide and Swivel

If I had to use a word to describe the PM-1 headphones from Oppo, it would be "clear". The biggest difference between the planar drivers and traditional dynamic drivers is the amount of silence you hear. When the music isn’t playing and it’s supposed to be quiet, it is. Notes start and stop without any “smearing” or  holdover. The dynamic range of the music seemed to increase exponentially compared to other headphones. This allows you to hear deeper into the music than you ever have before. You can hear nuances that were previously obscured by the less sophisticated driver technology of other high-end headphones.

oppo_pm-1_planar-driver

Oppo PM-1 Planar Driver

One thing you'll hear from reviewers is that a speaker or headphone is unforgiving of poorly recorded music. This usually manifests itself on the top end where the presentation becomes harsh and the compression artifacts seem to be exacerbated. I found that the Oppo PM-1 headphones didn't display this propensity. Instead, EVERYTHING sounded great. The slight roll-off on the top end likely contributed to this impression. Sure, I could hear that some music was recorded and mixed better than others, but it wasn't as if I couldn't tolerate MP3s or streaming services like Pandora and Spotify.

If anything, this made me like the PM-1 headphones even more. Who wants to spend $1,100 on headphones you can only use with HD music? If I spend that much, I want to be able to use them with all my music. The PM-1 headphones were the perfect headphone - they could let your high quality tracks sing while being kind enough to streaming services that you could use, and enjoy, them even for casual use.

 

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Recent Forum Posts:

AJM posts on November 13, 2015 20:05
I have owned these headphones for about a month. They are simply the best sounding and most comfortable headphones I have ever owned. I can listen to them for hours with no discomfort or listening fatigue. They replaced a set of Grado GS1000e cans, and although they are in the same price bracket, the PM-1 is everything the Grados should have been.
Karen Molinares posts on January 31, 2015 23:54
1CnozoFP9LI
Oppo PM-1 and PM-2 Headphone Review and Comparison
scaredsharp posts on September 11, 2014 18:27
Me want please pleaze
j_garcia posts on August 26, 2014 14:13
Got to hear these over the weekend. Honestly? They rock. As clear of a headphone as I've ever heard. Great sound top to bottom and bass was quite good. Most important thing I think though, they're really comfortable.
lillyblack82888 posts on July 15, 2014 18:41
Mm I may have to try these… they sound good.
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