Headphone CSD waterfall plots

[gurubhai]

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Looks like someone at Beyer trust his ears more than his his dummy head

I would love to see audiometry sheets of that guy !

 

[ZeNmAc]

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Or use an equalizer to tame the treble. Or try some mods. But I agree entirely, if the FR sucks the cleanest waterfall plots won't make the headphone sound great.

 
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Yes.  It depends on what bothers you and what you find more important.  And then for me, it's a balancing act, while some things are more bothersome than others, no one aspect will make a headphone sound great. 

Yup, FR can be eq'ed although you may need a good one for a permanent solution.  Nothing can be done about a bad csd (besides mods that may help but likely wont fix the problem).

 

[ultrabike]

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Yup, FR can be eq'ed although you may need a good one for a permanent solution.  Nothing can be done about a bad csd (besides mods that may help but likely wont fix the problem).

 
I wouldn't be so sure. Someone with a measuring rig and an appropriate equalizer might chime in on this and give a definitive answer.
 
CSD plots are a function of the impulse response, which in turn are a function of the FR magnitude and phase. The way I see it, certain types of equalizers (which can tackle FR magnitude and phase) might be able to "fix" a bad CSD to some extent. Obviously there are limitations to what an equalizer can do, and real world proof would have the ultimate say... and currently I don't have a measuring rig... So you can label this as arm chair theorizing if you choose.
 
That said, the new Beyers seem to have way too many issues. I would say best to get better headphones that to try equalize an expensive and problematic headphone. Talking from experience on this one: Keeping my KSC-75, sold my DT-990 250 ohm (a bit too bright and were not getting enough attention from me). Furthermore, the DT-990 250 ohm is considered less offensive (sonically and measurement wise) than the T5P by people I trust, therefore I can tell you I have no intentions on buying or even trying the T5P (among other Beyer offerings). 

 

[Anaxilus]

EQ cannot fix/change the physical/mechanical limitations of a driver.  Using a turbocharger on a 4 cylinder to make 400hp doesn't make it a 400hp V8.  EQ/DSP only takes care of half the problem.  
 
Ask any Apple lover.  Homeopathy=/=Chemotherapy.  

 

[ultrabike]

True. EQs cannot turn earbuds into 009's. But it may improve on some of the limitations of an otherwise good headphone, if properly used.

 

[maverickronin]

You'd need one hell of a DSP to even start to improve on those sorts of nasty ridges.

 

[ultrabike]

Based on Purrin's work, the T5P present quite a few notches that would likely be very challenging to even equalize. A shame Beyer is putting up this lackluster product on the market at any price (let alone > $1000)

 

[arnaud]

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CSD plots are a function of the impulse response, which in turn are a function of the FR magnitude and phase. The way I see it, certain types of equalizers (which can tackle FR magnitude and phase) might be able to "fix" a bad CSD to some extent. Obviously there are limitations to what an equalizer can do, and real world proof would have the ultimate say... and currently I don't have a measuring rig... So you can label this as arm chair theorizing if you choose.

You're misunderstanding what CSDs are. It has nothing it do with phase: these are snapshots of the magnitude response of a headphone over time.
One additional thing: CSD highlight issues with damping, or lack there of should I say. Again, damping has "nothing"  to do with phase (well it affects the slope of the phase change with frequency but still). 
 
Now, an equalizer working on the magnitude response (such as smoothing out a peak) while not correcting the phase will still have a positive effect on the CSD (simply the ridge for that resonance should be reduced or possibly split into two smaller ridges).
 
What probably is more difficult to fix are those ridges that are not plain obvious until you look at the CSD (those resonances that are lightly damped yet not dominating the response in the band).

 

[Joe Bloggs]

Someone needs to take the FR and waterfall plots, take a minimum phase EQ filter to the FR that flattens the FR and see what that does to the waterfall plot.  See how much of the "ringing" we see in the waterfall plots are simply inherent to the frequency response?
 
http://www.head-fi.org/t/566163/headphones-are-iir-filters-graphs
 
It would seem to me that if the headphone driver were a perfect minimum phase filter, correcting the frequency response with a minimum phase filter would produce a perfect impulse response and perfect waterfall plot?

 

[Joe Bloggs]

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Beyer T5P
 

 

 

 
No comment.

 
This looks kinda like what might happen if someone tried to equalize the phones to cancel out one particular person's ear canal resonances?  I tried to do it with a cheapo headphone the Panasonic HTF295 and this is the EQ curve I came up with:

The 6-10kHz region could have been even more jagged if I spent more time at it...
 
"Looks like someone at Beyer trust his ears more than his his dummy head"... indeed?

 

[purrin]

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Someone needs to take the FR and waterfall plots, take a minimum phase EQ filter to the FR that flattens the FR and see what that does to the waterfall plot.  See how much of the "ringing" we see in the waterfall plots are simply inherent to the frequency response?

 
With speaker drivers, peaks always correspond to ringing. But to throw a in wrench in the works, nulls also typically correspond to ringing. With headphone measurements, because there so much reflection and refraction (earcup, pads, etc.), we have less of an idea of what is going to happen. We'll see peaks without ringing, and ringing where there are no peaks (usually a frequency shift in the last case.) It's what arnaud said: those ridges which can be seen in the CSDs that are not obvious from looking at the FR graphs
 

http://www.head-fi.org/t/566163/headphones-are-iir-filters-graphs
 
It would seem to me that if the headphone driver were a perfect minimum phase filter, correcting the frequency response with a minimum phase filter would produce a perfect impulse response and perfect waterfall plot?

 
I've spoken with Matt Ashland at JRiver about coming up with usable IR files to put into the MC17 convolution filter. I've had limited success so far. I need much more time to dedicate to this project to make it work, and being the curious type, I want to make sure it works with my speakers in the first place. In theory it should work, but there are quite a few issues:
 

• The IR files need to be massaged into what we as humans hear instead of what the microphone/measurement system ears. While my measurements make an attempt to do this, they are only relative approximations based on comparisons with other reference playback systems.
• I would have to have to compensate accordingly IR --(FFTs)--> FR --(EQ)--> FReq --(iFFT)--> IR. (Or the raw IR could be used in the convolution filter and EQ/compensation applied during playback)
• Even then I would have concerns about the IR being obtained from steady state measurements, increased distortion (headphone response can be really wonky), and obliterating the designers intended voicing of the headphone.
• I need to write some code to convert IR in delimited text to a WAV file since that's what MC17 takes.
• A driver that wants to resonant like a drum is going to do so no matter what, despite DSP
• DSP convolution with an IR file may be a bit too much overkill, possibly causing other issues, because of the time scale and specific headphone sensitivities involved. DSP room correction works on the scale of 10s of milliseconds. DSP headphone correction would have to work on the scale of fractions of a millisecond. My general philosophy is to use the simplest tool to get the job done in an acceptable way. PEQ may be much simpler.

 
So far, this project is on hold. But it is interesting enough for me to pursue in the very near future.

 

[brokenthumb]

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Based on Purrin's work, the T5P present quite a few notches that would likely be very challenging to even equalize. A shame Beyer is putting up this lackluster product on the market at any price (let alone > $1000)

 
They also raised the MSRP recently to $1399 was $1295

 

[ultrabike]

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They also raised the MSRP recently to $1399 was $1295

 
Yeap. Not only that, take a look at the rave amazon reviews.

 

[Anaxilus]

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Yeap. Not only that, take a look at the rave amazon reviews.

 
Amazon tends to have good reviews for anything that doesn't come w/ an iPod.

 

[ultrabike]

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Amazon tends to have good reviews for anything that doesn't come w/ an iPod.

 
LOL

 
The sad thing is that not too long ago that was one of my primary sources of equipment impressions