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Old 11th August 2010, 03:52 AM   #7101
soongsc is offline soongsc  Taiwan
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I would be interested in seeing some CSDs if it's possible.
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Old 11th August 2010, 04:05 AM   #7102
mige0 is offline mige0  Austria
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Quote:
Originally Posted by Few View Post
After over 7000 posts there's little that can be considered off the topic(s) of this thread.

Few
LOL - "Beyond OT"


-----------

We possibly can summarize the steady state issue simple :
IR (as the time domain aquivalent of FR) is the „matrix“ to determine how input signals get deformed *and also* FR (as frequency domain aquivalent to IR) is the end result of that transformation process (input > output) we would hear „SPL wise“ after infinite time = steady state.

So we are running a little bit in circles here.


I guess thats been what Elias was focusing on.
I'm definitely with him that the steady state SPL plots do not sufficiently tell us what we "hear" - given the dynamic structure music distinguishes from "steady state". It needs some additional "reading the tea leaves" to get a good grip on the time behaviour with only a FR plot at hand - Time-freqency plots are IMO more intuitively to read in this respect.

The topic IMO is interesting in so far, as CMP can be seen to reach „steady state“ immediately – immediately at „time = zero“ and for the second part at exactly „time = time delay“ - and lastly for the "tail" as well
Which is untypical for any other time dependent variations in SPL (= resonance)

Besides that – and also to come back closer to the threads topic – I guess the most interest would be in how would a „as good as it gets“ EQ'ing of CMP look like – respectively – what are the artifacts of CMP distortion left.

Possibly - *if* we consider the 2.3 ms wiggle as a pure and simple reflection somewhere in the TD15M driver (which in reality most likely isnt *that* simple, but just for the sake of simplicity) - we could hypothesize a „as good as it gets“ EQ'ing and then check how the remaining CMP distortion possibly looks like ???

Michael

Last edited by mige0; 11th August 2010 at 04:31 AM.
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Old 11th August 2010, 05:32 AM   #7103
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So, after all this discussion (interesting as it is), has anyone bothered to get a strobe and look at the spider to see if it is the source of the 2.3ms wiggle?

Did anyone else explain the polarity inversion of the pulse?

Tonebursts at 2.3ms intervals could be revealing.

Mike
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Old 11th August 2010, 06:03 AM   #7104
soongsc is offline soongsc  Taiwan
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I was under the impression that there was no intension to tweek the driver.
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Old 11th August 2010, 06:08 AM   #7105
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I was under the impression that there was no intension to tweek the driver.
Good point. Anyway, here's a particular post that may or may not be relevant: Geddes on Waveguides
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Old 11th August 2010, 06:25 AM   #7106
soongsc is offline soongsc  Taiwan
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I think someone mentioned that possibility a few pages back. I was wondering whether that could happen to a spider at 2KHz or not. The only way to find out is to tweek it.
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Old 11th August 2010, 06:43 AM   #7107
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Originally Posted by soongsc View Post
I think someone mentioned that possibility a few pages back. I was wondering whether that could happen to a spider at 2KHz or not. The only way to find out is to tweek it.
Heh, guess I was echoing my own comment.

The frequencies contained within the wave packet could be as high as 2kHz.

Group velocity - Wikipedia, the free encyclopedia


Wouldn't it be cool if it was a physical manifestation of a de Broglie wave?
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Old 11th August 2010, 07:17 AM   #7108
soongsc is offline soongsc  Taiwan
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The impulse does not show that occuring.
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Old 11th August 2010, 07:41 AM   #7109
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The impulse does not show that occuring.
True. Sorry, I got carried away. I still have a lot to learn.

Thanks for your replies!

Best regards,

Mike
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Old 11th August 2010, 10:30 AM   #7110
JohnPM is offline JohnPM  United Kingdom
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To be accurate, log sweep cannot measure system's impulse response. Not unless you start the sweep from DC. But one cannot do that because it would take infinite time to play the sweep. Anything else yields only approximation of the impulse response. In practise approximations are often sufficient, but it does not remove the (approximate) steady state condition requirement. The more 'steady stateiness' in the log sweep the more accurate is the measured impulse response. That is, the longer the sweep the more accurate is the impulse response. To understand this try to think what will happen if you make your log sweep infinitesimally short in duration.
In the limit an infinitesimally short sweep is an impulse, and I think we know the term used for the output of a system when driven by an impulse. Perhaps you are aware that sweeps are also referred to as "time stretched pulses", particularly amongst Japanese researchers, and the motivation for their use is to spread the energy of the impulse out in time so that the total energy delivered is far greater than the system could cope with if an impulse were used directly. Or perhaps not.
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