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Oppo PM-1: A New Planar Magnetic Headphone! - Page 106

post #1576 of 2487
Is that chart not corrected for Fletcher Munson? If not, that's pretty close to what I measured, except with mine the bump up at the end was around 6kHz and it was half that size.
post #1577 of 2487

Frequency Response Raw is directly from the head with no compensation.

Frequency Response Compensated applies DF compensation.

Our standard Frequency Response applies averaging to smooth the graph with the intent of making it a little easier to read.

The Fletcher Munson curve is dependent on volume. I'm not sure how we would apply this to our measurements consistently but interesting to think about. 

post #1578 of 2487
Well you've got a line there that slopes down pretty much along with the sensitive areas of the hearing (Fletcher Munson). If it was corrected for that, you would have pretty much a straight line.

I measured the response by ear using tone sweeps at a normal listening volume. My measurements showed a basically flat response from 28Hz to 12.5kHz with about a 3dB bump at 3kHz and a 4dB bump at 6kHz. Measuring by ear isn't quite as accurate, particularly in the frequencies above 12kHz or so, but it gives you the *perceived* response curve, with all the various corrections automatically built in.

Your type of measurement is great for comparing one set of headphones to another. Measuring by ear shows how the cans will sound, pointing out which areas are neutral and which are boosted or cut.

I think what we're looking at with your graph is pretty close to the ideal response curve... basically audibly flat, even if the graph itself doesn't look flat.
Edited by bigshot - 4/18/14 at 3:27pm
post #1579 of 2487
It doesn't make any sense to apply a loudness correction as 1) you have no idea the comfort level at which one is listening to gear, 2) we're all having frequency dependent sensitivty bit it applies to live music, headphones and speaker listening the same - you don't see speaker measurements as loudness vs. frequency very often, do you?

Only place where I feel perceived overall loudness matching would help is in the curves comparison between phones (instead of arbitrary 250hz or 1kHz crossing point).

The stationary loudness model is well known and can be computed from spl curve, you end up with a single number, loudness in Sones (0 Sones = range of audibility, 10 Sone is background noise in an office I recall - not sire anymore). Anyhow, the idea would be to set a loudness level at which listener typically listens to (somewhere in 65-75dBA overall region I suppose?), and line up the curves at iso-loudness.
post #1580 of 2487
Most people shopping for headphones want a general idea of what they sound like listening to music at normal listening volumes. When the average person looks at a graph, they try to figure out how that sounds.
post #1581 of 2487

Does the frequency response change when using the velour pads?

post #1582 of 2487
I couldn't detect any difference, but I was evaluating it at a decent volume level. Maybe volume affects that too.
post #1583 of 2487
Quote:
Originally Posted by hodgjy View Post

Does the frequency response change when using the velour pads?

The measurement (and comparison against hd650/hd800 and lcd2) is very interesting: you can see the slight drop in bass / low bass response with the pm1, just like a velours pad hd650 or hd800. It highlights the fact that the leather pad is perforated (not sealed) , or measurements were performed with velour pads but we'd be told I think. I suspect both pads yield similar bass output / tuning, it's not just whatever piece of foam and clothes put together it appears.

Others have commented the velours doesn't sound drastically different from the leather but more open sounding, so i don't expect the velour to tilt the response even more to the dark / warm side, although it should in comparison to leather pad (at least non-perforated case).

Would love to see the actual graphs velours vs. leather though, i hope Tyll gets to it.
post #1584 of 2487
Quote:
Originally Posted by arnaud View Post

The measurement (and comparison against hd650/hd800 and lcd2) is very interesting: you can see the slight drop in bass / low bass response with the pm1, just like a velours pad hd650 or hd800.

Are we looking at Jamey Warren's graph, or another one? Above 20Hz, there's only a 4dB rise. That little that low isn't likely to be particularly audible when listening to music. Or are you saying that the HD-650 and HD-800 have bass boosts that velour pads reduce to sounding flat?
post #1585 of 2487
I am referring to the LF tuning of the driver:
- lcd2 is sealed chamber, hence flat all the way down to 10Hz
- pm1 is virtually identical to hd650 in the bass tuning, which is interesting as hd650 is open baffle / leaky pads (e.g velour, non-impervious). You get gently roll-off controlled by the amount of leakage through the pads and/or slit between pad and baffle.
- hd800 is virtually driver in free field, you get the most cancellation between front and rear wave

The graph:


Edit: the pm1 actually lines up with hd800, how surprising this is! Sometimes, tyll has serious issue with pad sealing against the dummy head, wonder if that's a possibility this time (has happened in the past)
Edited by arnaud - 4/18/14 at 5:43pm
post #1586 of 2487
To human ears, that is going to sound flat down to the edge of hearing. I'd imagine that a balanced response in the sub bass is the goal of any premium quality headphone. The bass in all the cans on your comparison chart is the same.
Edited by bigshot - 4/18/14 at 6:08pm
post #1587 of 2487
Quote:
Originally Posted by jerg View Post
 

Thanks!

 

Here's the non-smoothed version of the same measurement (just change 4343 to 4342 in the url):

 

 

if you take in account the fletcher munson curve.. this is a very very nice FR even the peek at 10000 is nice ..

 

Easy to EQ to taste if necessary (missing some air maybe btw 10khz and 20khz i would pad down -5db or -7db for everything between 60hz(at the bump) to 12000khz or boost before and after =) not sure what would be better... a crossoverless super tweet btw 10-15khz to 40khz flat would be nice =)

 

It's the CSD decay that i'm affraid ove ... im sure impulse is pretty good in a planar anyway


Edited by Audiolic - 4/18/14 at 6:55pm
post #1588 of 2487
Quote:
Originally Posted by bigshot View Post

To human ears, that is going to sound flat down to the edge of hearing. I'd imagine that a balanced response in the sub bass is the goal of any premium quality headphone. The bass in all the cans on your comparison chart is the same.

 

It's not about sub-bass extension but the profile of the curve which indicates the driver loading type. If you include the bass / mid-bass response (so 50-200Hz), you can certainly notice differences between these phones. And, certainly,  HD650, HD800 and LCD2 don't quite "all sound the same" in the bass/mid-bass department... 

post #1589 of 2487

I liked the Fostex RP prototype when I compared it against the TH900 at previous audio festival. In particular it sounded more balanced / less agressive than the TH900. The PM-1 could be sharing some similarities with the fostex: 

 

post #1590 of 2487
Quote:
Originally Posted by arnaud View Post
 

 

It's not about sub-bass extension but the profile of the curve which indicates the driver loading type. If you include the bass / mid-bass response (so 50-200Hz), you can certainly notice differences between these phones. And, certainly,  HD650, HD800 and LCD2 don't quite "all sound the same" in the bass/mid-bass department... 

 

Maybe I'm reading that chart wrong, but the widest difference is about 6dB apart at 20Hz. By 30Hz, 3dB. As it goes up through the bass and mid bass, they are all huddled together tight with less than 2dB difference all the way up to 1kHz. Any difference in the sound of the bass would have to come from distortion or dynamics or something like that, not frequency response. Weird... Maybe I'm looking at a different chart than you are.

 

I also don't see how your read the 12 to 15dB boost on the whole bass range on the Fostex as being similar to the Oppos. Totally confused here.


Edited by bigshot - 4/18/14 at 7:49pm
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