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Headphone CSD waterfall plots - Page 38

post #556 of 932
1/24/12 at 10:22am
Thread Starter 
Quote:
Originally Posted by morks View Post

@purrin: Could you slap a 10-band-Eq with -4 dB at 8 kHz on that T1 and measure it again? I'm curious what the effect on the FR and resonances is. Hum... then again, I tested 2 equalizers in maybe not equal circumstances, but they sounded different with the same setting... mh. maybe I'm doing it wrong.

 

My measurement rig won't support a digital EQ. The two equalizers could have differing curve widths. This makes a huge difference. Try a parametric EQ where you can pick a frequency and curve Q.

 

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post #557 of 932
1/24/12 at 11:50am
Thread Starter 

HE-500 and LCD2r2 
 

Quote:
Originally Posted by rhythmdevils View Post

I miss seeing new CSD plots every day. 

 

Again, typical reminders:

 

  1. These are not FR plots and shouldn't be taken as such.
  2. Note scale of frequency, time, and floor.
  3. Note floor is -36db which is deeper than most of my other graphs (of this style.)
  4. Time is compressed - goes out to 4ms.

 

HE500L.txt.jpg HE500R.txt.jpg

 

Impressive results with the HE500. Consistent decay with no ridges except a very low magnitude one on the left channel at 5k (resonances at 5k are typically benign.) I found the HE500 ever-so-slightly dark sounding from a vintage Sansui 5000 receiver and neutral with slight brightness from the ECBA (as I have it configured.) I tried listening for problem spots (ringing / resonances) and didn't hear any (although the 10k FR peak is notable.) I noted by ear a slight depression at 6-8k which isn't nearly as bad as measurements indicate. I suspect there is a measurement artifact at that spot (the CSD sort of confirms it.) [As an aside, the HE500 does not extend in the bass as well the LCD2r2, which can crank out low and sub bass at extreme volumes.]

 

LCD2r2 driver L.txt.jpg LCD2r2 driver R.txt.jpg

 

Also very good results with LCD2r2. The short lived ridges at 6k and 7k are audible to me, but not too bad with the right setup. (I can live with them, but I'm almost sure RD will want to punch someone in the face.) Also very slight ringing on left channel at 12k. I didn't notice this at all (but have on other r2s I've heard.) This particular r2 had slightly less bass impact than the two best r2's I had heard. The shelf is not seen well because the roll-off actually starts around 300Hz (the graph starts at 500Hz) with this unit. Otherwise I'm not going to comment too much on the LCDr2 because it seems every other person and his sister has one on HF.

 

Both the LCD2r2 and HE-500 waterfalls mostly die at -36db by 1ms, with the HE-500's decay being a hair quicker toward the end.

 

Beyer T1 for comparison.

T1 R.txt.jpg


Edited by purrin - 1/24/12 at 12:26pm
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post #558 of 932
1/24/12 at 2:15pm


 

Quote:
Originally Posted by purrin View Post

HE-500 and LCD2r2 

 

 

Thank you for these last measurements, I was waiting for quite some time for HE-500 CSD plots.

Please, your comments about the significant resonance around 700Hz in both channels for HE-500. Is it a measurement artefact or a real one?

If it is a real one, I suspect that resonances at frequencies below 1 KHz are probably not malignant, and they may contribute to the ‘creaminess’ in vocal, but may also  mask some details. I think I am hearing a resonance around 200Hz, also, with low Q, but that’s well below your graph’s frequency spectrum.

 

Again, many thanks for this and all your very valuable contribution!

 

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post #559 of 932
1/24/12 at 2:36pm
Quote:
Originally Posted by purrin View Post

HE-500 and LCD2r2 
 

 I tried listening for problem spots (ringing / resonances) and didn't hear any (although the 10k FR peak is notable.)

 

 

Funny think is that this resonance is very apparent on Tyll’s data, not only in FR but, most importantly, on impulse response. It is evident for at least 2mSec. Maybe it is a resonance of the headphone cup and not of the transducer, so it is not apparent to your special measurement setup and not easily spoted by hearing?

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post #560 of 932
1/24/12 at 3:53pm
Thread Starter 
Quote:
Originally Posted by plin View Post


 

 

 

Thank you for these last measurements, I was waiting for quite some time for HE-500 CSD plots.

Please, your comments about the significant resonance around 700Hz in both channels for HE-500. Is it a measurement artefact or a real one?

If it is a real one, I suspect that resonances at frequencies below 1 KHz are probably not malignant, and they may contribute to the ‘creaminess’ in vocal, but may also  mask some details. I think I am hearing a resonance around 200Hz, also, with low Q, but that’s well below your graph’s frequency spectrum.

 

Again, many thanks for this and all your very valuable contribution!

 


Usually stuff below 1-2k past 2ms are enclosure effects. I don't hear anything "off" at 700Hz.

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post #561 of 932
1/24/12 at 8:36pm

Any plans to make one of these for the Magnum v 4?

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post #562 of 932
1/24/12 at 9:31pm
Quote:
Originally Posted by dorino View Post

Any plans to make one of these for the Magnum v 4?


Yup.

 

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post #563 of 932
1/25/12 at 4:44am

I am surprised you could get acoustic resonance down to 700Hz , maybe quarter wavelength for an open type headphone? That would still have to make it about 12 cm from the base of the earpad to the open end of the earcup, quite a big headphone! Felt and other porous materials effectively lower that resonance (make the earcup feel bigger in terms of acoustic waves propagating, but 700Hz still seems quite low...

 

 

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post #564 of 932
1/26/12 at 11:54am
Quote:
Originally Posted by arnaud View Post

I am surprised you could get acoustic resonance down to 700Hz , maybe quarter wavelength for an open type headphone? That would still have to make it about 12 cm from the base of the earpad to the open end of the earcup, quite a big headphone! Felt and other porous materials effectively lower that resonance (make the earcup feel bigger in terms of acoustic waves propagating, but 700Hz still seems quite low...

 


I am not an expert here, so please excuse me if I am missing something, but I do not believe that mechanical resonances are only made because of air standing waves in headphones. I cannot really understand the physics behind ortho operation, but every mechanical structure has some sort of resonance. In an ortho headphone there may be no resonances directly from the plastic membrane that produces the sound, but there are other potential sources, like the magnet structure, the ear cups, even the headband.

Anyway, I made an interesting experiment. I plug my HE-500 in my laptop mic input, using it like a huge microphone. In a quite room I singly hit in various places the ear cups and the metallic grill with a metal knife. I recorded the output with audacity (see attached image). I repeated this many times.

 

In every hit there is a residual resonance which fades away rather quickly. This resonance has a period of 136 samples. With 44100 samples per second, this makes a frequency of around 325Hz.

 

HE-500 as a mic hitted with a knife

 

With this, rather crude, way I captured the vibrations of the plastic membrane of the ortho transducer when I hit the ear cup and the metallic grill. Of course this doesn’t necessarily mean that this same resonance exists when HE-500 is normaly used, as a headphone, but it is not unlikely.

So, a relative low frequency resonance probably exists. Maybe this is one of the reasons for the euphonic ‘creamy’ mids of HE-500.

 


Edited by plin - 1/26/12 at 12:23pm
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post #565 of 932
1/26/12 at 9:40pm

Good stuff purrin.  Thanks for all the time and effort you put into getting graphs for us! biggrin.gif

 

Any chance at getting harmonic distortion graphs too? biggrin.gif

 

*sigh* headroom's 500hz distortion graph annoys me a little.  I think it's just to impress the ppl who don't know what that means.  Either that or ppl are more serious about getting clean midbass than I thought eek.gif.

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post #566 of 932
1/26/12 at 9:58pm

You have no idea how serious I am about clean midbass!  tongue.gif

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post #567 of 932
1/26/12 at 10:05pm

Mid-bass is my greatest foe! mad.gif

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post #568 of 932
1/27/12 at 6:25am

Mh, sorry for deing so demanding purrin, but would it be possible to measure the T1 again, this time with an output impedance of 100 or 120 Ohm via a stick-inbetween-adapter or something? Beyer's own A1 has that output impedance, curious to see what effect it has on FR and the rest. This reminds me, what kind of source are you using for the measurements, anyway?

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post #569 of 932
1/27/12 at 6:43am


 

Quote:
Originally Posted by plin View Post

I am not an expert here, so please excuse me if I am missing something, but ...


I am amazed by how clever some of you guys are! Somehow, people who have no background in measurements / acoustics have such ability to think outside the box! This verification by reciprocity is very neat!

 
Note that there may have been a misunderstanding: I was responding to purrin who mentionned it was probably an acoustic resonance (or I misread, need to read again), and that does not sound feasible to me at 700Hz based on small dimensions of the earcup.
 
I did not mean there was no resonance that could occur at 700Hz or lower. Indeed there could be headband mechanical resonance or driver / membrane mechanical resonance. 
 
You'd need to make an FFT on your recording to confirm, but yeah, it would seem like there's a pretty sharp (undamped) resonance there. All I was saying is that I think it's not an acoustic standing wave in the earcup... 
 
In your case, given you were hitting the headband and earcups and measuring the response through the transducer membrane by reciprocity, it's hard to tell if this is a driver or frame resonance. If I had to guess though, between earcup and headband, I'd clearly pick the headband for a 300Hz resonance...
 
If you can send me a text file with the time data you got (need the sampling rate or time & response vectors), I'll be happy to generate a frequency response and possibly a csd curve.
 
Cheers, arnaud
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post #570 of 932
1/27/12 at 10:19am
Thread Starter 
Quote:
Originally Posted by arnaud View Post

I am amazed by how clever some of you guys are! Somehow, people who have no background in measurements / acoustics have such ability to think outside the box! This verification by reciprocity is very neat!

 
Note that there may have been a misunderstanding: I was responding to purrin who mentionned it was probably an acoustic resonance (or I misread, need to read again), and that does not sound feasible to me at 700Hz based on small dimensions of the earcup.
 
I did not mean there was no resonance that could occur at 700Hz or lower. Indeed there could be headband mechanical resonance or driver / membrane mechanical resonance. 
 
You'd need to make an FFT on your recording to confirm, but yeah, it would seem like there's a pretty sharp (undamped) resonance there. All I was saying is that I think it's not an acoustic standing wave in the earcup... 
 


Yeah - acoustic standing wave caused by the cavity would be impossible given the length of a 700Hz wave and the size of the cup. What I really meant what anything outside of the driver (doubtful it's driver ringing at these diaphragm sizes.) There seems to be some correlation with how the < 1.5/2kHz area looks like with certain earcup/headband designs, e.g. a lot of the Senn headphones look similar to each other (and cleaner than that of other manufacturers')

 

EDIT: I am wondering if it's the metal gimbal assembly. It is sort of shaped like a tuning fork. If I have time today, I'll run it on the RTA and tap on the gimbal.


Edited by purrin - 1/27/12 at 11:13am
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