John Curl's Blowtorch preamplifier part II - Page 3345 - 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 24th January 2013, 08:49 AM   #33441
fas42 is online now fas42  Australia
diyAudio Member
 
fas42's Avatar
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 11
Refreshing to see some movement on considerations apart from the textbook electricals -- hmmm, I wonder if I can patent "Everything matters ...". Uhh, oh ... I think Mike in the UK has got there first ...

Frank
  Reply With Quote
Old 24th January 2013, 10:27 AM   #33442
bcarso is offline bcarso  United States
diyAudio Member
 
Join Date: May 2005
Location: Canoga Park, California
Default forgive the whimsey

I got a different sound after a while when I used plywood for the heatsink
  Reply With Quote
Old 24th January 2013, 11:30 AM   #33443
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
.... and don't forget smell is also part of the perceptive experience

jan
__________________
If you don't change your beliefs, your life will be like this forever. Is that good news? - W. S. Maugham
Check out Linear Audio!
  Reply With Quote
Old 24th January 2013, 12:31 PM   #33444
PMA is offline PMA  Europe
Design engineer, consultant
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
Quote:
Originally Posted by gpapag View Post
Then after plywood, test with another kind of wood.


George
You do that, not me . And please also do not invite me for listening tests of plywood vs. oak cover. Thank you .
__________________
Pavel Macura
http://web.telecom.cz/macura/audiopage.html
  Reply With Quote
Old 24th January 2013, 01:52 PM   #33445
diyAudio Member
 
Max Headroom's Avatar
 
Join Date: Jan 2013
Location: West Australia, straight over the road from the beach, natural ambient sounds only.
Default Loudsinks...

I am well familiar with heatsinks 'singing' according to power amplifier output level and loading, and differences according to heatsink construction and shape....also rubber bungs between fins intended to damp/prevent heatsink 'singing'.
Ditto transformers and other components also, but IME producing rather lower acoustic level and different spectrum (ie sound) compared to typical aluminium heatsinks.

My initial question is more to do with measurement data showing spectral and distortion harmonics differences imparted by otherwise identical steel or aluminium enclosures....anybody quantified this ?.

Thanks, Dan.
  Reply With Quote
Old 24th January 2013, 01:56 PM   #33446
diyAudio Member
 
jneutron's Avatar
 
Join Date: Jan 2004
Location: away
Quote:
Originally Posted by DF96 View Post
That is defining the total current. No time integral is stated or implied. To define a sinusoidal current you need to specify its frequency and amplitude. This they do. Amplitude for AC currents is usually specified either as peak or RMS. They use RMS.

It is slightly puzzling, as EM theory usually uses peak current, but it has no significance for what you are saying. So there is nothing in the paper to say that they are using a time average. This is, of course, because they are not using a time average.
Yes, they concentrate only on dI/d(theta). Yet nowhere is a derivation attempted to discern the integrated resistance and subsequent IR drop over time. Of course, that was not their intent.
Nor did A. B. Dwight back in 1923. His paper is a virtual duplicate of the one being discussed. I am delighted to find that papers from the 20's are available via google and IEEE btw...some of the best stuff on this topic is from '58 back.

Quote:
Originally Posted by DF96 View Post
That may be so, but the authors do not say so;
So your sticking point is that I said the word eddy currents as discussed within their document, you agree that they were talking about eddy currents, but now you are hung up on the fact that they did not specifically say the word eddy currents when they were talking about eddy currents and I pointed out they were talking about eddy currents????

Is that what your gonna hang your hat on??.

jn

ps..this discussion with you is nice. I would have it no other way, thank you for your time and effort..
  Reply With Quote
Old 24th January 2013, 02:14 PM   #33447
diyAudio Member
 
Esperado's Avatar
 
Join Date: Jul 2011
Location: France
Quote:
Originally Posted by gpapag View Post
>Edit. As I have promised not to add noise to this thread,
What is the ratio of useless posts witch can be considered as noise contribution in this thread ?

This said, you were very near, indeed, to advice cones and choose of rare woods ;-)

I'm, like you, sure that the change of this amp's sound, depending from the cover's material, can be measured and explained. Or some noise from the PSUs, or some microphonic part in the amp, like a poor weld or poor contact somewhere or some mechanical element, playing a role of capacitance, and sensible to vibrations.
As habit, the bad way to solve this problem is the audiophile way: playing with material's quality, OMHO.

As said Chuck Norris, "When the wise man points at the moon, the fool looks at his finger".
__________________
Ultimate Protection and more.The Only Source of Knowledge is experience, everything else is just information” ©A. Einstein

Last edited by Esperado; 24th January 2013 at 02:37 PM.
  Reply With Quote
Old 24th January 2013, 02:41 PM   #33448
PMA is offline PMA  Europe
Design engineer, consultant
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
Quote:
Originally Posted by Esperado View Post
What is the ratio of useless posts witch can be considered as noise contribution in this thread ?
My vote is 99.9% useles, 0.1% valuable. But even those 0.1% are sometimes damned interesting
__________________
Pavel Macura
http://web.telecom.cz/macura/audiopage.html
  Reply With Quote
Old 24th January 2013, 03:10 PM   #33449
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Well, PMA, put forth some more interesting ones. You don't have to be as negative as these other guys, you know what it takes to build good audio equipment. Show us some more measurements, or simulations. I certainly learn from them!
  Reply With Quote
Old 24th January 2013, 03:21 PM   #33450
diyAudio Member
 
Esperado's Avatar
 
Join Date: Jul 2011
Location: France
Quote:
Originally Posted by PMA View Post
But even those 0.1% are sometimes damned interesting
+1
i've learned or my attention have been pointed on various interesting things i do not worried enough about.
Reason why we all stay trolling or shaking the coconut here, i believe.
Thanks to John, (among some others), even if i am far to agree all the time with him. The issues he raises are often interesting.
__________________
Ultimate Protection and more.The Only Source of Knowledge is experience, everything else is just information” ©A. Einstein

Last edited by Esperado; 24th January 2013 at 03:24 PM.
  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 12:13 PM.


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