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Old 28th August 2012, 06:35 AM   #7881
DeonC is online now DeonC  South Africa
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What is happening on with the green curve at circa 20kHz? It looks like hectic ringing or breakup.

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Old 28th August 2012, 06:56 AM   #7882
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Originally Posted by DeonC View Post
What is happening on with the green curve at circa 20kHz? It looks like hectic ringing or breakup.

Deon
Might be the brickwall filter of the soundcard; many of the 96/24 cards retain a hardware, non-defeatable 20 kHz lowpass filter on the ADC side of things. The only way to be really sure that a 20 kHz brickwall filter isn't there are factory specs that quote noise and distortion out to 40 kHz or higher.

If the specs are only quoted out to 20 kHz, there are good odds the soundcard has a 20 kHz brickwall filter that cannot be removed - unless you are comfortable circuit-tracing and removing SMD components.

Soongsc, I'm curious to see the Before and After pictures on the 3" driver, as well as an efficiency spec (I'm guessing 82~85 dB/meter/watt).

Last edited by Lynn Olson; 28th August 2012 at 07:04 AM.
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Old 28th August 2012, 07:45 AM   #7883
DeonC is online now DeonC  South Africa
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Thanks, Lynn, that could be it. It is scary to think what sometimes happens to the signal in the digital part of some systems. Me, I like digital, but I prefer good old analogue. There is something just so right and relaxing about the watching that black disc spin. It's just more hands on. But maybe I'm just giving my age away here.

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Old 28th August 2012, 08:05 AM   #7884
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Just a question about CSD how do you interpret the results, at what point is something considered an audible effect?
I could imagine it would be very easy making a mountain out of mole hill with these sought of measurements (still trying to decide whether the pun is intended)?
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Old 28th August 2012, 10:35 AM   #7885
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Originally Posted by soongsc View Post
John, while letting the acoustic target match the ideal can improve CSD performance, the ideal target is not ideal. I think this would be more evident if you used a full range driver to do testing. I would
The point was and remains that if the drive is minimum phase, the target is minimum phase and the EQ is minimum phase, then the EQed driver response will have the same CSD as the target. It doesn't matter what the shape of thew target transfer function is or the frequency range of the driver.

Here are a couple of additional links to web pages I put up back in April when discussing this with Joachim:

Page 1 Midrange (before and after)

Page 2 Tweeter (Neo 3) (before and after)


Both CSD and burst response are shown, as well as HD (at a frequency where there was a significant resonance) since there was some (incorrect) speculation about the effect of the EQ on distortion.

Anyway, I'm not sure how this relates to current thread on Lynn's speaker. These were done using the UE.
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Old 28th August 2012, 11:05 AM   #7886
soongsc is offline soongsc  Taiwan
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Originally Posted by DeonC View Post
What is happening on with the green curve at circa 20kHz? It looks like hectic ringing or breakup.

Deon
Green curve is the phase which corresponds with the cone breakup mode. When you have cap and cone not reaching breakup mode at the same time, that is a point difficult to compensate for no matter what.
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Old 28th August 2012, 11:15 AM   #7887
soongsc is offline soongsc  Taiwan
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Originally Posted by john k... View Post
The point was and remains that if the drive is minimum phase, the target is minimum phase and the EQ is minimum phase, then the EQed driver response will have the same CSD as the target. It doesn't matter what the shape of thew target transfer function is or the frequency range of the driver.

Here are a couple of additional links to web pages I put up back in April when discussing this with Joachim:

Page 1 Midrange (before and after)

Page 2 Tweeter (Neo 3) (before and after)


Both CSD and burst response are shown, as well as HD (at a frequency where there was a significant resonance) since there was some (incorrect) speculation about the effect of the EQ on distortion.

Anyway, I'm not sure how this relates to current thread on Lynn's speaker. These were done using the UE.
I think we got into the discussion when Lynn mentioned stored energy.

I wish SoundEasy had the potion to display CSD in periods, it will more easily show damping relationship with frequency since it is audibly desireable to not only have sound decay fast, but have the same damping characteristic.

I will study the links some more.
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Old 28th August 2012, 11:52 AM   #7888
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I wish SoundEasy had the potion to display CSD in periods, it will more easily show damping relationship with frequency since it is audibly desireable to not only have sound decay fast, but have the same damping characteristic.
I suggested that to Bohdan probable 5 or 6 years ago. It would not be hard. All that would need to be done is to rescale the time values by multiplying by f. The problem is with the way Bohdan stores his data. Anyway, I'm out of the the SE/UE loop.
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Old 28th August 2012, 12:18 PM   #7889
soongsc is offline soongsc  Taiwan
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Originally Posted by Lynn Olson View Post
Might be the brickwall filter of the soundcard; many of the 96/24 cards retain a hardware, non-defeatable 20 kHz lowpass filter on the ADC side of things. The only way to be really sure that a 20 kHz brickwall filter isn't there are factory specs that quote noise and distortion out to 40 kHz or higher.

If the specs are only quoted out to 20 kHz, there are good odds the soundcard has a 20 kHz brickwall filter that cannot be removed - unless you are comfortable circuit-tracing and removing SMD components.

Soongsc, I'm curious to see the Before and After pictures on the 3" driver, as well as an efficiency spec (I'm guessing 82~85 dB/meter/watt).
Some times I measure with 48KHz sample rate setting sometimes I use 96KHz, since UE runs at 48KHz under this case measurement at 96KHz can produce some funny graphs. However, I don't see it effecting what I am trying to present.
UE Eqed
Click the image to open in full size.
Before
Click the image to open in full size.
The driver sensitivity is speced at 87db/M/W, after treatment, it reduced about 1db. But what difference to you think it will make?
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Old 28th August 2012, 12:27 PM   #7890
soongsc is offline soongsc  Taiwan
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Originally Posted by Melon Head View Post
Just a question about CSD how do you interpret the results, at what point is something considered an audible effect?
I could imagine it would be very easy making a mountain out of mole hill with these sought of measurements (still trying to decide whether the pun is intended)?
My experience is this:
Technically, the high level after time zero is like the driver itself mixing noise into oncoming playback music.

What it sounds like is a more difficult thing to explain unless you listen to before and after. But if you compare two that have pretty much similar frequency response, you can relate the sonic signature with specific CSD long decays. Generally, I find some 12db difference in CSD more obvious.
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