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Oppo PM-1: A New Planar Magnetic Headphone! - Page 107

post #1591 of 2527
Quote:
Originally Posted by bigshot View Post

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.

Coming from the speaker world, you should know better than this. A slight change in speaker alignement has a limited impact on the frequency response but the effect is quite visible in the impulse response / transient response.
I am not sure you have experience with the lcds and senns, but the bass presentation is rather different.

Quote:
Originally Posted by bigshot View Post

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.

Misinterpretation. I am extrapolating what i heard (th900 vs. rp prototype) with what is shown (th900 vs. pm1).
post #1592 of 2527
Quote:
Originally Posted by arnaud View Post


Coming from the speaker world, you should know better than this. A slight change in speaker alignement has a limited impact on the frequency response but the effect is quite visible in the impulse response / transient response.
I am not sure you have experience with the lcds and senns, but the bass presentation is rather different.
Misinterpretation. I am extrapolating what i heard (th900 vs. rp prototype) with what is shown (th900 vs. pm1).

Definitely agree with you, looking at FR graphs the LCD series and HE-500 and HD-800 have more or less similar curves in the bass and treble(sic. Midrange), however no one is going to say those headphones all sound the same.


Edited by Ultramus - 4/18/14 at 10:55pm
post #1593 of 2527

You've got a 15db spread in the heart of the treble between the HD-800s and the Oppos. I wouldn't expect the treble sound alike at all. The Senns have a treble boost.

 

I still don't understand how bass is going to sound different if it measures the same though. Bass isn't particularly directional.

post #1594 of 2527
Directionality has absolutely nothing to do with the discussion at hand lol. There are things like transient response, how tight the bass feels rather than round sounding which may not be that easy to visualize with just a FR.

Boomy bass with a poor alignement would be obvious in the FR response but, as you said, we're at a higher quality level with the phones compared. Doesn't make them sound the same in the bass register however.

Again, if we look at this with a shovel, give or take 5dB, I agree it's all the same but I think some of us are a bit more subtle in our perception of gear SQ smily_headphones1.gif.
post #1595 of 2527
Quote:
Originally Posted by Jamey Warren View Post
 

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. 


Could you explain DF compensation?

post #1596 of 2527
Quote:
Originally Posted by Headphoner View Post
 


Could you explain DF compensation?

The Head Acoustics mic we use comes with two compensation curves, one for Diffuse Field, and one for Free Field. We use the "Diffuse Field" one. There is a big debate in the headphone world as to which is the proper compensation but what we have available currently is the Diffuse Field compensation. We're considering offering other compensation curves but it's not easy for us at the moment.


Edited by Jamey Warren - 4/19/14 at 12:27am
post #1597 of 2527
Quote:
Originally Posted by bigshot View Post
 

You've got a 15db spread in the heart of the treble between the HD-800s and the Oppos. I wouldn't expect the treble sound alike at all. The Senns have a treble boost.

 

I still don't understand how bass is going to sound different if it measures the same though. Bass isn't particularly directional.

I mistyped, I meant they have similar FR in the bass and midrange, treble is where they all diverge from one another.

post #1598 of 2527
Quote:
Originally Posted by arnaud View Post

Again, if we look at this with a shovel, give or take 5dB, I agree it's all the same but I think some of us are a bit more subtle in our perception of gear SQ smily_headphones1.gif.

 

The most important thing in reading specs is to have perspective about the things that make huge differences and the things that don't. It's easy to say that your hearing is subtle and refined and 5dB differences are mountains not molehills if you don't ascribe to any baseline. When you do that, it seems like everything is huge.

 

For myself, I put a lot of importance on the big things and less on things that don't make a significant difference. I have a pair of the Oppos sitting next to me right now, and not only does that frequency response curve describe the sound of them good enough that I would have a good idea of how they sound even if I hadn't heard them; that response curve plus correction for Fletcher Munson is almost exactly what I got by measuring by ear using two different methods.

 

If you have a sense of proportions and understand what the numbers mean, you can get a lot of information from well measured specs. If you understand the numbers, but focus on gnat wings and convince yourself that they make all the difference, it's a lot harder.

post #1599 of 2527
Quote:
Originally Posted by Ultramus View Post
 

I mistyped, I meant they have similar FR in the bass and midrange, treble is where they all diverge from one another.

 

Yes, and I would expect that if I did a listening comparison of them, I would come to the same conclusion.

post #1600 of 2527

Okie dokie, here's my measurements.

 

The first one is the Leather pads, velour on the second.

Click the image to get the .pdf

 

 

 

 

 

I'll have a LOT to say about these measurements when I do the review, but for the moment I'll draw your attention to the 2 little blips on the impedance curve at 250Hz and 400Hz. You'll also note a rise in THD+noise at those frequencies. These are blips due to a dual primary driver resonance---one is the diaphragm as a whole, and the other is the driver resonance of a more central portion of the driver that has a different resonance due to the traces on the diaphragm surface.  I got all this info from Igor via email. My brief interpretation here may or may not be totally accurate, but it should be close.

 

You'll also notice that the THD+noise as a whole----other than the blips---is VERY low, and the blips don't hit the 1% level untill you get to 100dBspl.  It's very important to note here that THD+noise is a pretty uninformative measure, and there are types of distortion that are more disturbing than others, and all will be reported similarly on THD+noise measurements. For example, if the distortion is even-order, it will be much less disturbing than if it is odd-order. The point is, when looking at these artifacts, it's important to note that the peaks in distortion are really quite small, they just look big relative to the very low distortion otherwise.

 

I have spent very little time listening to these cans, but my initial impression is that they have a smooth, creamy sound that's very pleasant, though maybe a little muffled sounding...just a little, but this headphone plays in the reference headphone area and nits are worthy of picking. I have lots more listening to do however. I will be listening to see if I can hear the distortion or not.  I will take some measurements of harmonic structure using a probe tone at the two peaks and nearby the peaks to see if the harmonics change ratios significantly---IOW, at the distortion frequency there may be more second or third harmonic at the peaks than in undisturbed areas.

 

Igor said he agreed that the measurements are representative of the product. Personally, I'd rather not see the distortion blips there, but Igor's explanation was quite thorough and sensible, and it seemed to me we may have one of those cases where the measurements are telling us something that's a bit complicated, and you can't just say "more distortion is bad" with any kind of certainty.

 

I will happily say right now though, that the build quality, comfort, looks, and accessories of these headphones is top-notch.  

 

This is going to be an interesting headphone.

post #1601 of 2527

Well, for those that were questioning the effect of the Velor pads...  You just got your answer.  Better extension and balance with them (according to the graphs) in the sub-bass by a few dB (at most).  The square waves also have a smaller first peak with the Velors. 

 

The other two graphs are in agreement as well about the softer treble. 

post #1602 of 2527
Quote:
Originally Posted by meetoo1 View Post
 

Could some please contrast and compare the Beyerdynamic T1 to the PM-1?  I'm really interested in the difference in SQ between the two.

 

I wish I still had them for a more "accurate" comparison, but I feel several months spent with the T1 gives me at least some ability to say that no matter what source and amp you're using, the PM-1's bass energy is higher than that of the T1 and it's more efficient than the T1. That's probably not news to you, but I'll stop there.  :o 

post #1603 of 2527
Quote:
Originally Posted by tinyman392 View Post

Well, for those that were questioning the effect of the Velor pads...  You just got your answer.  Better extension and balance with them (according to the graphs) in the sub-bass by a few dB (at most).

Are you talking about 10-20Hz? That isn't the sub bass. It isn't even audible.
post #1604 of 2527

I agree with bigshot here, I care about sub-bass a lot and really it is only relevant down to maybe 25 Hz or so. As long as the drop-off from 35 Hz to 25 Hz is fairly shallow, sub-bass extension is perfect in practice.

post #1605 of 2527
I don't see any difference there between the leather and velour pads. (I didn't hear any difference when I compared them, so I'm really not surprised.)
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