John Curl's Blowtorch preamplifier part II - Page 1138 - diyAudio
Go Back   Home > Forums > Member Areas > The Lounge

The Lounge A place to talk about almost anything but politics and religion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th March 2011, 06:30 PM   #11371
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by scott wurcer View Post
Sorry I wish had more time yesterday that was a hurried post. I don't think we need the esoteric references. Let me take a step back because I think I have an experiment that anyone can do.


"I have coils on my desk which are made using 700 or so turns of 15 guage solid copper, and some made using equivalent guage litz. Measurement of both from 20 hz to 50 Khz clearly shows the equivalent series resistance of the solid goes nuts, exceeding 300 to 400 ohms at 20Khz.
Am I being told that both will have the exact same noise should I push 20 Khz 1 ampere into them?"


Yes, except for heating and other non-ideal effects


Gosh, I meant that all the noise would be accounted for by the real part of the resistance at 20kHz. This does get confusing. And this can be measured from the terminals with only the self noise as a "signal".
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."

Last edited by scott wurcer; 15th March 2011 at 06:34 PM.
  Reply With Quote
Old 15th March 2011, 06:36 PM   #11372
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by ikoflexer View Post
+1

Cheap shots on either part makes one look bad no matter the status or level.
That is why I prefer .22 for target shooting much less costly than larger calibers, but it does make you look silly on the range when everyone else is shooting relatively speaking cannons!

That was also an off topic bit for those who are satire impaired.

Can we continue with Scott's experiment?

Scott I find it a bit hard to conduct from the telegraphic post, why don't you flesh it out.

John, I take it you did not get my email or don't agree with it.

ES
  Reply With Quote
Old 15th March 2011, 06:38 PM   #11373
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Quote:
Did you post eddy loss/series resistance before me?
I don't know. My memory is poor, and I can't claim to have read the whole thread. I don't claim to be the first to mention eddy current as an issue.

However, we have been arguing for a few days about the nature of the eddy current issue. I claim thermal noise arises from this loss mechanicm, and you were disputing this. You were saying that there is a noisy back-reaction against a signal, but that would mean no noise from this mechanism if there is no signal. I'm not sure if we now agree or still differ!
  Reply With Quote
Old 15th March 2011, 06:53 PM   #11374
diyAudio Member
 
scott wurcer's Avatar
 
Join Date: Jan 2004
Location: cambridge ma
Quote:
Originally Posted by simon7000 View Post
That is why I prefer .22 for target shooting much less costly than larger calibers, but it does make you look silly on the range when everyone else is shooting relatively speaking cannons!

That was also an off topic bit for those who are satire impaired.

Can we continue with Scott's experiment?

Scott I find it a bit hard to conduct from the telegraphic post, why don't you flesh it out.

John, I take it you did not get my email or don't agree with it.

ES
Ed, I was suggesting the same thing as DF96. The noise in the system is a signal and you will always see the effects of the eddy losses. Measure the Q of a coil and then make a parallel LC circuit with it resonant at the same frequency. Then look at the voltage noise across this circuit. You will see the equivalent resistance (loss) in the noise spectrum. I see I was confused by JN's extraneous information (20kHz at 1A). The 1A is irrelevant the coil will look like 400 Ohms at 20k and have sqrt(1600*KT) nV/rt-Hz of noise at 20kHz.
__________________
"The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important."
  Reply With Quote
Old 15th March 2011, 07:27 PM   #11375
diyAudio Member
 
jneutron's Avatar
 
Join Date: Jan 2004
Location: away
Quote:
Originally Posted by john curl View Post
JN, you have never taught me anything of significance in all of our interactions.
I know. But it's not for my lack of trying.

Happened when I tried to explain EMC compatibility issues in your test equipment when you claimed you upscaled that old ST1700 with new electronics but neglected any and all ground loop issues..remember that thread?

Happened when you claimed the diffusion velocity of electrons was the fermi velocity.. You even got some prof in florida (if I recall) to try to "splain" to me how something I never said wasn't correct..

Happened when you were brandishing Hawksford's very bad and quite inaccurate skin theory goop.

But yes, you are correct..I never taught you anything. You're like a horse I've led to water, yet you'll die of thirst...

Quote:
Originally Posted by john curl View Post
Perhaps, it is just me, but I do tend to 'muddle on' to make successful audio products.
No, you do not muddle. You experiment, you use your observational skills, your produce excellent product as a result (from what others have told me..remember Phil Tower?).
Quote:
Originally Posted by john curl View Post
The very idea of 'keeping me honest' is a slight, that I do not appreciate it, like so many other comments that you made toward me.
No, it's a point of humor. You need to develop a sense of humor..

Quote:
Originally Posted by john curl View Post
I have NEVER knowingly lied or gave misinformation on this or any other website in my life experience.
Never said that. Never will. edit: and, I would argue anybody who claimed such inappropriately.

You divert, John..

Quote:
Originally Posted by john curl View Post
I don't know EVERYTHING, but I know a lot, and I always appreciate any REAL input from engineers and physicists that actually gives more insight to audio design.
Aw gee, guess that leaves me out, eh??

Quote:
Originally Posted by scott wurcer View Post
Gosh, I meant that all the noise would be accounted for by the real part of the resistance at 20kHz. This does get confusing. And this can be measured from the terminals with only the self noise as a "signal".
I was hoping you'd correct that. Now you are in agreement with me...(perhaps now would be a good time for you to rethink your stance??.)

Quote:
Originally Posted by simon7000 View Post
John, I take it you did not get my email or don't agree with it. ES
John who? Me? (edit...got it, thanks)

Quote:
Originally Posted by DF96 View Post
I don't know. My memory is poor, and I can't claim to have read the whole thread. I don't claim to be the first to mention eddy current as an issue.
I do claim that. Of course, I've not read the entire thread either, so I'm not gonna look for anything that bursts my bubble...

Quote:
Originally Posted by DF96 View Post
However, we have been arguing for a few days about the nature of the eddy current issue. I claim thermal noise arises from this loss mechanicm, and you were disputing this. You were saying that there is a noisy back-reaction against a signal, but that would mean no noise from this mechanism if there is no signal. I'm not sure if we now agree or still differ!
You know, I'm not sure either. However, I believe we are not arguing. This has been an intelligent discussion. (don't burst that bubble either..please)

But I'm confident that the mechanism can be measured via a two terminal effective resistance test at frequency..and that if there is no signal present, the noise would be consistent only with the coil itself regardless of the core construction assuming consistent inductance. Remember, measurement of the coil noise voltage by itself doesn't push current, so there will be no coupling to the core such that the inductance of the core and/or eddy loss is involved.

Quote:
Originally Posted by scott wurcer View Post
I see I was confused by JN's extraneous information (20kHz at 1A). The 1A is irrelevant the coil will look like 400 Ohms at 20k and have sqrt(1600*KT) nV/rt-Hz of noise at 20kHz.
Yah, sorry about that. My tests have been 20 to 20k and 1 ampere to ascertain phase shift and eddy/winding losses, so naturally I just used it..

So I guess we all agree that the noise generated at a specific frequency will be dependent on the Rs component of the Ls-Rs model?

And that by using equipment like the HP 4284A to measure Ls-Rs from on terminal set, we should be able to determine equationally the amount of noise that will result from both proximity and eddy dissipation.

That would be a very good coup....

Cheers, John

Last edited by jneutron; 15th March 2011 at 07:48 PM.
  Reply With Quote
Old 15th March 2011, 07:31 PM   #11376
jlsem is offline jlsem  United States
diyAudio Member
 
jlsem's Avatar
 
Join Date: Jun 2003
Location: Dallas,TX
Quote:
Originally Posted by Steve Eddy View Post
Can you cite an example of this so I can take a look at what you're talking about?

se
Click the image to open in full size.

I said a slight rise but as you can see, permeability effectively doubles at 20kHz near saturation, which would seem to be related to domain stiction issues.

John

Last edited by jlsem; 15th March 2011 at 07:53 PM.
  Reply With Quote
Old 15th March 2011, 07:34 PM   #11377
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by scott wurcer View Post
Ed, I was suggesting the same thing as DF96. The noise in the system is a signal and you will always see the effects of the eddy losses. Measure the Q of a coil and then make a parallel LC circuit with it resonant at the same frequency. Then look at the voltage noise across this circuit. You will see the equivalent resistance (loss) in the noise spectrum. I see I was confused by JN's extraneous information (20kHz at 1A). The 1A is irrelevant the coil will look like 400 Ohms at 20k and have sqrt(1600*KT) nV/rt-Hz of noise at 20kHz.
Scott,

The issue I have with adding my noise to the currents swirling around here is my rule is that I cannot discuss anything that involves other folks' secret sauce recipes.

From what you have written I can still read it several ways. One way I can give you useful results, the others and I am still not here.


ES

Last edited by simon7000; 15th March 2011 at 07:47 PM.
  Reply With Quote
Old 15th March 2011, 07:40 PM   #11378
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Quote:
Originally Posted by jneutron View Post
So I guess we all agree that the noise generated at a specific frequency will be dependent on the Rs component of the Ls-Rs model?

And that by using equipment like the HP 4284A to measure Ls-Rs from on terminal set, we should be able to determine equationally the amount of noise that will result from both proximity and eddy dissipation.

That would be a very good coup....
Tell ya what, if anyone's equipped and willing to do this, I'll provide a CineMag CMMI-10C 1:10 microphone input transformer.

se
__________________
The Audio Guild
  Reply With Quote
Old 15th March 2011, 07:43 PM   #11379
diyAudio Member
 
Join Date: Nov 2008
Location: Oakmont PA
Quote:
Originally Posted by Steve Eddy View Post
From Soft Magnetic Materials for Audio Transformer: History, Production and Applications:

For the higher frequencies in the audio range there is the
"skin effect," that is, the flux tends to concentrate on the
outer surface of the laminations, which accounts for the
fall in effective permeability, as shown in Fig. 16.


se
Steve

Just yesterday I had to scream at Scott for posting an old and important paper anyone could understand. And here you are doing the same thing!

About the only issue that it did not make completely clear was why increasing the inductance of the transatlantic cable helped to carry the signal. Most folks would have assumed that the increased inductance would decrease the signal strength.

Are you now going to point them the papers on that issue that explain when there is capacitance and inductance in the right ratio's you have a constant impedance? So raising the inductance will actually result in a more uniform loss without frequency peaking?

Shame, shame, shame...

ES
  Reply With Quote
Old 15th March 2011, 07:48 PM   #11380
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Quote:
Originally Posted by jlsem View Post
I said a slight rise but as you can see, permeability effectively doubles at 20kHz near saturation, which would seem to be related domain stiction issues.
Thanks.

Yes. Could be. I'm afraid I haven't an answer for this one.

se
__________________
The Audio Guild
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 07:18 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2