John Curl's Blowtorch preamplifier part II - Page 2963 - diyAudio
 John Curl's Blowtorch preamplifier part II
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gedlee
diyAudio Member

Join Date: Dec 2004
Location: Novi, Michigan
Quote:
 Originally Posted by SY Very well, but some quibbles: minimum phase can apply to nonlinear systems as well. The only requirement is that the phase be the derivative of the amplitude response wrt to frequency. And single valued functions indeed contain no loops, but if (for example) you have a 2d function unwinding in a 3d space, you can inadvertently have multiple values which are not loops in the 2d representation. Rooms have 3 dimensions (assuming the room size is time invariant!), the signal applied to them has one dimension plus time. So, no minimum phase (there's delays from reflections) and multiply valued (amplitude varies over space as well as time).
Since the concept of "Minimum phase" (MP) comes from "linear systems theory" it is dangerous to try and apply it to a nonlinear system. It may appear to be MP at one level and not at another one - so is it or is it not MP? It cannot be defined.

Also MP is a one dimensional concept and has no multidimensional meaning. A room can be MP from a source to one point and not be to a different point - again it cannot be defined.
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kgrlee
diyAudio Member

Join Date: Nov 2011
Location: Cooktown, Oz
Quote:
 Originally Posted by Wavebourn I thought you understand the difference between damping of ringing and equalizing the rest of response that can't be tamed mechanically?
I'm sorry Guru Wave. I'm just trying to add to my knowledge & experience from my own poor attempts at these techniques of which you are expert.

But I'm confused You say
• You've tried the 0R1 resistor, PFB bla bla method
• unlike other people, you find no distortion advantage
• There is a need to make sure Impedance of speaker is flat
• But no need to compensate for the bass resonance in a speaker which is surely the biggest feature in a speaker's impedance
• That Audyssey solves everything
• Audyssey DOESN'T solve everything
So can you explain what advantage your PFB, 0R1 resistor gives which Audyssey doesn't? Please use simple words suitable for dummies.

Do you see less ringing with the PFB? Is this acoustic or electrical? Is it at LF?

Messrs George & SY, I'll pontificate a little about Minimum Phase later cos I'm a pseudo guru on the subject .. especially as it pertains to speakers & rooms.

Banned

Join Date: Jul 2011
Location: Portugal
Quote:
 Originally Posted by kgrlee cos I'm a pseudo guru on the subject
You too ?
Did-you suffer slings and arrows ?

 My English humor is pathetic.

Last edited by Esperado; 20th November 2012 at 06:56 PM.

Wavebourn
diyAudio Member

Join Date: Sep 2006
Location: Pleasant Hill, CA
Quote:
 Originally Posted by Esperado You too ? Did-you suffer slings and arrows ?
It is hard to tell what he suffered, but as the result he definitely acts as if he sees contests in any discussion.
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The Devil is not so terrible as his math model is!

Banned

Join Date: Jul 2011
Location: Portugal
Quote:
 Originally Posted by Wavebourn It is hard to tell what he suffered
Hard ? Mr kgrlee is the patient, not the disease.

jneutron
diyAudio Member

Join Date: Jan 2004
Location: away
Quote:
 Originally Posted by Esperado Hard ? Mr kgrlee is the patient, not the disease.
Darn. I was hoping to use the phrase "your a disease, I'm the cure"

jn

Wavebourn
diyAudio Member

Join Date: Sep 2006
Location: Pleasant Hill, CA
Quote:
 Originally Posted by jneutron Darn. I was hoping to use the phrase "your a disease, I'm the cure"
It is called Symbiosis
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The Devil is not so terrible as his math model is!

PMA
diyAudio Member

Join Date: Apr 2002
Location: Prague
My favorite example. These signals differ only in phase of one of the spectral components. For absolutely identical amplitude spectra, we get totally different time domain signals. One of them will push the amp to clipping, the 2nd will not .....

One has to be careful when working with amplitude spectra only. It is only a half of the necessary information.
Attached Images
 fourier1.PNG (38.3 KB, 163 views) fourier2.PNG (37.3 KB, 162 views)

Last edited by PMA; 20th November 2012 at 07:40 PM.

jneutron
diyAudio Member

Join Date: Jan 2004
Location: away
Quote:
 Originally Posted by Wavebourn It is called Symbiosis
No. It's called Cobra, as in Cobretti.

jn

 20th November 2012, 07:54 PM #29630 jneutron   diyAudio Member     Join Date: Jan 2004 Location: away Quote removed from post that was removed. I believe he was responding to your posting verbage with sarcasm. I must admit that what you wrote could be read several ways. It would be nice if you both stood down. I enjoy tremendously the technical content you both provide, and wish it to remain above animosity. thanks, jn

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