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Finding value in headphone measurements

Chocomel

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What would be the best way of measuring how fast a driver is? I'm also referring to the sounds the driver does when raising and falling too (would these be added harmonics that will reflect in the final THD?). Thank you!

Considering headphones are generally minimum phase, high frequency extension at higher output levels, basically slew rate i guess. Although I'm not sure about the limit of this behavior in Headphones in regards to the Frequency range, afaik it generally holds for the audible band.
 

outerspace

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What would be the best way of measuring how fast a driver is? I'm also referring to the sounds the driver does when raising and falling too (would these be added harmonics that will reflect in the final THD?). Thank you!
If driver can reproduce 20 kHz signal of desirable magnitude then it's fast enough. If it can reproduce tones from 20 Hz - 20 kHz range with acceptable amount of distortions then it's accurate enough. There is no speed characteristics beyond that.
 
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Mad_Economist

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I noticed that almost regardless whether or not I use a headphone that has a very wide frequency range or one that just reaches say 15khz my mic. always shows about the same risetime when using a squarewave. It seems to be limited to an equivalent of 16kHz bandwidth, roughly.
I am sure there is an explanation for this (mad economist will probably know).
As you say, the risetime is a proxy of bandwidth here - off the top of my head, nothing's coming to mind for why two headphones with drastically differing high-frequency bandwidth should be identical in that respect; can you post a couple of examples with both the square waves and the frequency responses overlaid?
 

solderdude

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I suspect it is the mic. in my case WM61A.
It can measure up to 30kHz but is rolled off a bit.
rise time kam2 old pads.png

Probably related to this. I also compensate for this in hardware which also may have to do with my reported issue.
response.jpg
John coonver.png

From: http://www.johncon.com/john/wm61a/
Quite certain if I used an earthworks or other wideband mic I would get better risetimes.
The moral of my story is that it doesn't matter for bass as the risetime for higher 'bass' frequencies is already met.
 
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Robbo99999

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People's who's not posted yet read the OP, I'm guessing your voice is to be heard!
 

cistercian

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You know... as I packed the 5128 to send it back I got sad. Maybe it was because the thing almost looks human. :) In reality I think it was because as flawed as the measurements are headphones are, it gave me a personal insight I did not have about them. Nor had I gotten that from reading a bunch of graphs elsewhere.

When I measure things, I try to tease out a story. What is the device about? Why is it acting the way it is? What does it net out to? As much as there are headphone sites out there with extensive measurements, I miss this in them.

OP gives me hope that there is more we can measure to get that story. Even if we don't want to buy something, it is good to be informed about what is out there.

I am very interested in "what is out there" even if I am not planning to buy. Paradigm changes happen and I am usually late
to embrace the change...but I want to be informed when I dive in! This site is invaluable for this.
Also, because I am a well rounded geek, I really like being informed of the state of the art. Watching the progress being made
is an end unto itself as I seriously appreciate the engineering involved.
 

trl

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If driver can reproduce 20 kHz signal of desirable magnitude then it's fast enough. If it can reproduce tones from 20 Hz - 20 kHz range with acceptable amount of distortions then it's accurate enough. There is no speed characteristics beyond that.
So how can we measure "fast bass" or "slow bass" in the end? Pure sines of let's say 30Hz or maybe 50Hz, then check timing differences vs. the original sinewave?
 

Doodski

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So how can we measure "fast bass" or "slow bass" in the end? Pure sines of let's say 30Hz or maybe 50Hz, then check timing differences vs. the original sinewave?
Could use a 2 channel oscilloscope and compare the input and output waveform if one wants to view it that way.
 
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Mad_Economist

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So how can we measure "fast bass" or "slow bass" in the end? Pure sines of let's say 30Hz or maybe 50Hz, then check timing differences vs. the original sinewave?
Timing differences? It's a sine wave...

Edit: Obviously, there will be delay from D/A conversion, sound pressure propagation, A/D conversion, etc - but other than delay, you won't be seeing much. @outerspace's point is that driver "speed" is equivalent to bandwidth, and anything that can play 20khz with the desired linearity and output level is sufficient in this regard.
 

trl

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I am aware of the above, thank you, but still doesn't tells much about the fast vs. slow bass. This is also happening on subs, not just on headphones, so how we can measure how "fast" is the bass if square waves Tyll used for that are not OK. Thanks!
 
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Doodski

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I am aware of the above, thank you, but still doesn't tells much about the fast vs. slow bass. This also happening on subs, not just headphones, so how we can measure how "fast" is the bass is square waves Tyll used for that are not OK. Thanks!
Can you clear up your comment/English a bit. I'm not sure what you are asking for.
 

solderdude

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So how can we measure "fast bass" or "slow bass" in the end? Pure sines of let's say 30Hz or maybe 50Hz, then check timing differences vs. the original sinewave?

I would suggest to select 2 headphones of which you feel has fast and slow bass and have a look at Rtings to see the actual phase and amplitude differences to see if you see some relevance there.
Rtings measures acoustical phase where most others measure electrical phase.

The whole idea of measuring headphones is to relate to what is heard otherwise it is pointless to measure them at all.
 
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JohnYang1997

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There's really no fast or slow bass, at least not what people think.
To compare these things you have to equalize the frequency response to the same first.
Now, there are differences in the bass. If you have a ported driver the phase will be different than a unported. Majority of dybamic drivers have port for bass. There are exception for both. Etymotic mc5 mk5 and er2se don't have port. Etymotic er4xr being BA driver has port.
Then after Equalization to electrically flat, you can use CSD now. There may be some longer decay time for some headphones or some designs. But in general the decay time is too short to make a difference.
 

Chocomel

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Using the excess group delay in REW is a nice option to check for any abnornal behavior, which you could then further check out with for example burst decay. I would note that especially the lower frequencies will be prone to noise so if you see some rise there in the excess group delay there that's likely the cause.
 

JohnYang1997

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Using the excess group delay in REW is a nice option to check for any abnornal behavior, which you could then further check out with for example burst decay. I would note that especially the lower frequencies will be prone to noise so if you see some rise there in the excess group delay there that's likely the cause.
There is much more to it. Headphone measurements have many caveats.
 

DualTriode

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@Mad_Economist

What I want out of headphone testing is what I want out of testing anything else. I want to put my hands and eyes on things and wrap my head around the DUT. It is fun learning and understanding. Kind of an addiction thing with me.

In my case I paid my dues in the university labs. Later I went out to client facilities to sort things in the big real world lab.

It is amazing the computer power that we have on our test benches. We can accomplish things that we could not a generation ago.

I have a cheap IEC711 ear simulator and a fake silicone ear coming from China in a couple of weeks. I have my suspicions that I can do a lot of testing with $200 worth of equipment. Later I will compare and calibrate with the GRAS 45CA.

Thanks DT
 

DualTriode

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We could be losing focus here.

Are we measuring human ears and hearing. I believe that this has already been done.

Or are we measuring headphones to quantify their performance.

Think about it, we do not get all into the human anatomy and physiology when we measure speaker performance.

You would think that we would want to remove all the individual human variables and have a consistent reliable way of measuring headphones.

Then we can bring it back to individual brains and ears with target and correction curves.

Thanks DT
 
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