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Oppo PM-1: A New Planar Magnetic Headphone! - Page 102

post #1516 of 2548

Can the guys using the term elaborate what they mean by "bright midrange" - bright is a term i associate with, and which is usually used to describe, treble.    Do they mean "forward midrange"?

 

TIA!

post #1517 of 2548
The mids, especially in the vocal range, is almost devoid of any distortion at all. Combined with the clarity of a flat response, there is no auditory masking, so the midrange sounds amazingly clear and lifelike. It isn't a frequency imbalance they're referring to, it's a clarity thing.

I used several albums by Joni Mitchell and Ry Cooder to evaluate these headphones and the midrange vocals and acoustic guitar sounded uncannily real. Better than my speaker rig even, and that's saying a lot.
post #1518 of 2548
Quote:
Originally Posted by bigshot View Post

I measured the Oppos and the copy i had was as flat as dammit out to about 12.5kHz. That is well beyond the treble range.

How's that well beyond?!
post #1519 of 2548

Not really sure if this is where I should be responding; apparently some of the thread has been shifted around.

 

I got some welcome suggestions on my original posts about the measurements of the PM-1 on About.com Stereos. Someone suggested measuring distortion at a lower level, and I'd already done a 90 dBA measurement for SoundStage, so I added that in the chart: http://stereos.about.com/od/Measurements/ss/Oppo-Digital-PM-1-Headphone-Measurements_5.htm.

 

Note that because no headphone's response is linear, the test level will be well above 90 dB at some frequencies and below 90 dB at others. 90 dBA is just an average, weighted toward the midrange. For example, I measured the level at 500 Hz with the PM-1 and it was 99.9 dB, so this is more or less equivalent to a measurement taken using a 500 Hz reference tone at 100 dB. (Which I don't do because using 500 Hz as a reference frequency would give a big advantage to headphones that have a response bump at 500 Hz.)

 

It was also suggested that I change the Y axis to a log scale. I wish I could do that, but Clio doesn't offer that option, at least not anywhere I can find. (It uses log Y scale on THD vs amplitude measurements, but not THD vs. frequency.)

 

Another suggestion was to have a floor of 0.001% THD on the chart. That's a good floor for amplifier measurement, but it's probably lower than needed for acoustical measurements. That's -100 dB. Based on the speaker measurements my colleagues at SoundStage do in the anechoic chamber at the NRC in Ottawa, it looks like somewhere around 0.1% might be the lowest you'd need for a transducer. The 50% max on my chart is definitely high, but I've measured a few headphones that actually got up to around 30%. Not headphones you guys would probably use, of course.

 

Jay_WJ said (among other things): "One thing to add: Do not generalize too much about correlation between measured performance and audibility. Scientific grounds on this issue (how audible particular levels and patterns of nonlinear (even linear) distortions would be to human ear under various, realistic conditions) are very weak at the moment." Totally, completely agree. AFAIK, the only place we have any decent understanding of the effects of transducer distortion on listener perception is with subwoofers.


Edited by bbutterworth - 4/17/14 at 1:07am
post #1520 of 2548
Quote:
Originally Posted by meetoo1 View Post
 

I don't understand why there are two separate threads for the same headphone... but,

Does anyone have both the PM-1 and Beyerdynamic T1?  If so, can contrast and compare them?

The other threads for sicophantic praise only, this threads for anyone who wishes to have an intelligent discussion about the PM-1 :-)

post #1521 of 2548
Quote:
Originally Posted by khatch View Post

Ok, I've had mine running in for 24 hours now and I spent approximately 3 hours today listening to them - both critically and casually. I'm bald, with a big head and large ears. Generally speaking, I'm very sensitive to issues of comfort and fit. I have found the Audeze line utterly unwearable - for more reasons than I care to describe. The PM-1 is, in a word, sumptuous. It's absolutely a delight to look at and it vanishes when on my head. The sound? Good.....maybe great. At least very enjoyable. But ironically, all I can think of after 3 hours on my head is how good they make my HD-650s sound and feel. That is NOT what I expected.

Interesting, I got rid of the HD-650s in favour of the Hifiman HE-400 which, in my system, offerer a superior sound.

post #1522 of 2548
Quote:
Originally Posted by bbutterworth View Post

Not really sure if this is where I should be responding; apparently some of the thread has been shifted around.

I got some welcome suggestions on my original posts about the measurements of the PM-1 on About.com Stereos. Someone suggested measuring distortion at a lower level, and I'd already done a 90 dBA measurement for SoundStage, so I added that in the chart: http://stereos.about.com/od/Measurements/ss/Oppo-Digital-PM-1-Headphone-Measurements_5.htm.

Note that because no headphone's response is linear, the test level will be well above 90 dB at some frequencies and below 90 dB at others. 90 dBA is just an average, weighted toward the midrange. For example, I measured the level at 500 Hz with the PM-1 and it was 99.9 dB, so this is more or less equivalent to a measurement taken using a 500 Hz reference tone at 100 dB. (Which I don't do because using 500 Hz as a reference frequency would give a big advantage to headphones that have a response bump at 500 Hz.)

As far as I know what people do when measuring distortion is they drive the headphones to the same decibel level at the microphone for all frequencies, so a headphone that is, say, 10dB down at 30Hz compared to 1000Hz should be driven 10dB harder at 30Hz to reach the same SPL (e.g. 90dB) at the mic at 30Hz and 1kHz.

This is evidenced by a common correlation between a response dip in the FR plot and a spike in the distortion plot for many headphones measured by e.g. innerfidelity.
post #1523 of 2548
Quote:
Originally Posted by khatch View Post

Ok, I've had mine running in for 24 hours now and I spent approximately 3 hours today listening to them - both critically and casually. I'm bald, with a big head and large ears. Generally speaking, I'm very sensitive to issues of comfort and fit. I have found the Audeze line utterly unwearable - for more reasons than I care to describe. The PM-1 is, in a word, sumptuous. It's absolutely a delight to look at and it vanishes when on my head. The sound? Good.....maybe great. At least very enjoyable. But ironically, all I can think of after 3 hours on my head is how good they make my HD-650s sound and feel. That is NOT what I expected.
What Dac and amp are you using? Maybe your amp has better senergy with HD650 then PM-1?
post #1524 of 2548
Quote:
Originally Posted by olegausany View Post

What Dac and amp are you using? Maybe your amp has better senergy with HD650 then PM-1?

Anything is possible. For this comparison I'm using a Wyred4Sound mINT.
post #1525 of 2548
Quote:
Originally Posted by conquerator2 View Post

How's that well beyond?!

Treble range is about 2kHz to 8kHz. 10-20kHz is the last octave in human hearing. Most people over 50 can only hear half of that. The only place where frequencies above 10kHz exist in music is in cymbal crashes, and even there it's pretty much inaudible because of frequency masking. A roll off at 12.5kHz isn't a huge deal. The balance of the frequencies below that are MUCH more important than the extension of the ones above it.
post #1526 of 2548
Quote:
Originally Posted by bbutterworth View Post

I got some welcome suggestions on my original posts about the measurements of the PM-1 on About.com Stereos. Someone suggested measuring distortion at a lower level, and I'd already done a 90 dBA measurement for SoundStage, so I added that in the chart: http://stereos.about.com/od/Measurements/ss/Oppo-Digital-PM-1-Headphone-Measurements_5.htm.

Loweriing the volume sure made a big difference.
post #1527 of 2548
Quote:
Originally Posted by bigshot View Post


Treble range is about 2kHz to 8kHz. 10-20kHz is the last octave in human hearing. Most people over 50 can only hear half of that. The only place where frequencies above 10kHz exist in music is in cymbal crashes, and even there it's pretty much inaudible because of frequency masking. A roll off at 12.5kHz isn't a huge deal. The balance of the frequencies below that are MUCH more important than the extension of the ones above it.

That is your personal bias though. You downplay extension so much but LOTS of people in this hobby view it as something critical to a truly "high fidelity" audio experience.

 

I don't know why you can't just admit to the fact that a relatively early treble roll-off is a flaw in the context of this hobby (not saying PM1 has that, measurements are notoriously bad at >10kHz detection).


Edited by jerg - 4/17/14 at 9:37am
post #1528 of 2548
Quote:
Originally Posted by jerg View Post

That is your personal bias though. You downplay extension so much but LOTS of people in this hobby view it as something critical to a truly "high fidelity" audio experience.

There are people that consider all sorts of crazy things to be critical to a truly "high fidelity" experience, but that doesn't make it so.

Listen to what 12.5kHz sounds like in tones. It's just a mosquito bug flying in your ear. No musical instrument in the orchestra produces fundamentals anywhere near 12.5kHz. In fact, just about all the important harmonics are under 12.5kHz. 10-20kHz is one octave- 8 notes. Above 12.5 kHz is about 6 notes on a piano- 6 notes up at the top reaches of human hearing! Most people over fifty can't hear the top four notes anyway, so for them we are talking about 2 notes up at the top of their hearing range.

Balance in the core frequencies is the thing that sets good heaphones apart from great ones. If you want something critical, there it is... and it's difficult to achieve too. The better the balance between 40Hz and 10kHz, the better the headphones. The outer octaves of human hearing are the least important. But given the choice, I'd choose sub bass over the top octave any day of the week.

The Oppos are flat to 12.5 and roll off from there. That doesn't add up to a hill of beans. All this is pretty clear if you take the time to figure out what the numbers actually sound like.

By the way, most specs that include a huge frequency extension don't list the range of variability. 50kHz means even less if it's -40dB. The Oppos are 28Hz to 12.5kHz +/-3dB. That impresses me, even if you don't know how special that is.
Edited by bigshot - 4/17/14 at 10:07am
post #1529 of 2548
Quote:
Originally Posted by bigshot View Post

Listen to what 12.5kHz sounds like in tones. It's just a mosquito bug flying in your ear. No musical instrument in the orchestra produces fundamentals anywhere near 12.5kHz. In fact, just about all the important harmonics are under 12.5kHz. 
 

 

I quite like warm, somewhat rolled-off treble - however, I am not sure i agree with your assertion above.   Just b/c there is no fundamental note in the last octave doesnt mean that severe roll-off in that region doesnt affect the timbre of an instrument.    Some people do like it & some people do want it.  

 

Typical audio measurements are in the 20-20kHz range, and we'd laugh at an amp that rolled off @ 12.5KHz.   So why are we suddenly arguing that this roll-off is irrelevant (note - for my tastes, it is indeed irrelevant, but that is a matter of preference, not a universal truism).

post #1530 of 2548
Treble stops around 8-9kHz. If you take your favorite song and dial out everything above 12kHz using an equalizer, you probably won't hear any difference at all. Like I say, it's important to know what sound corresponds to what number.

The timbre of an instrument depends on harmonics. Just about all of the audible harmonics in instruments fall below 12khz. A roll off over 12kHz is likely only going to affect synthesizers and cymbals, and even then, probably not in any audible way.

click to see in higher resolution

As for amps vs headphones... Just about everything between amps and transducers are different. Solid state amps are pretty much all audibly transparent... ruler flat response, no audible distortion, plenty of dynamics. But transducers are an entirely different kettle of fish. Response deviations of +/-20dB are common. Distortion as high as 4 or 5%. Frequency extension that cuts off 2 octaves at each end... Specs like this aren't really surprising.

The reason that we put up with specs in headphones and speakers that we don't have to with amps or players is because we don't have any choice. It just isn't as easy to design something that produces mechanical sound to the same specifications as electronics or digital audio.

The specs on the Oppo PM-1 are fantasic in all the places where most normal headphones fall down. The fact that they don't reproduce frequencies totally accurately that aren't even present in music doesn't matter nearly as much as what they do well.
Edited by bigshot - 4/17/14 at 11:53am
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