John Curl's Blowtorch preamplifier part II - Page 4854 - 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 February 2014, 10:20 AM   #48531
PMA is offline PMA  Europe
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
Quote:
Originally Posted by jacco vermeulen View Post
Sst, it's how I recondition light bulbs.
Please send me the test-recovery file data in *.wav, I'd like to try it as well.
__________________
Pavel Macura
http://web.telecom.cz/macura/audiopage.html
  Reply With Quote
Old 24th February 2014, 10:44 AM   #48532
gk7 is offline gk7
diyAudio Member
 
Join Date: Oct 2007
Location: Vienna, Austria
Quote:
Originally Posted by VladimirK View Post
...
Everybody who did it reported "wow".
For an even increased "wow" effect try whiskey "burned in" for 20 years or so...
  Reply With Quote
Old 24th February 2014, 11:16 AM   #48533
diyAudio Member
 
Join Date: Feb 2007
Location: Tashkent
Quote:
Originally Posted by gk7 View Post
For an even increased "wow" effect try whiskey "burned in" for 20 years or so...
Yes, this is also not a bad practice, sometimes, with good armagnac (for me). And one could also try white-noise signal burning-in, if square wave is dangerous. It would be wise to make this simple procedure first, before developing joking.

Last edited by VladimirK; 24th February 2014 at 11:21 AM.
  Reply With Quote
Old 24th February 2014, 11:59 AM   #48534
a.wayne is offline a.wayne  United States
Sin Bin
 
Join Date: May 2008
Location: Front Row Center
I usually let a green amp run for 48 hrs before listening , interesting you run @ 80% for 24hrs I do agree break in is needed and essential on everything , annealing is suggested , what about compaction ..?

@Sy,

Are you serious about reversing procedure ...? If so then Wire direction after break in is very important ...
  Reply With Quote
Old 24th February 2014, 01:09 PM   #48535
diyAudio Member
 
Max Headroom's Avatar
 
Join Date: Jan 2013
Location: West Australia, straight over the road from the beach, natural ambient sounds only.
In my servicing career, I have observed an interesting initial burn in' effect, many times.
One of my amplifier standard servicing procedures (particularly for PA amplifiers) is to blanket resolder the power supply and output stages....this helps to ensure long term reliability, and reveals sub optimal solder joints that on first inspection would seem to be ok.

So, after this rework, my procedure is to power up via lamp and variac whilst checking DC conditions.
If all is good, I then reconnect to standard wall power, and allow thermal conditions to stabilise (lid on), whilst periodically checking and adjusting bias currents as required.
Usually, I will allow this no signal process to progress over four or more hours.

The next step is to audition the amp with known source, known programme material, and known speakers....ie my quite good quality reference bench system.

Initially listening is at low volume/power for extended period.
Then, I gradually raise the volume and listen closely.

The curious thing with fully reworked amplifiers that I have found repeatedly, is that at low levels, initially the sound is 'wrong', badly 'wrong' and this distortion gets worse as the volume is slowly raised, and reduces as the volume is decreased.

When a threshold is reached (first clip events ?), the amplifier/sound suddenly and dramatically changes for the better, and remains so, even after repeated volume changes, power up/down cycles, or fully cold restart.

This once only effect is perhaps not as stark as I have described, however a trained ear alerted to this behaviour will discern the sonic changes.

I expect that the likely explanation is that ferrous materials get demagnetised during the soldering process, and gentle clipping sets a magnetisation level in DC current path ferrous containing components.

Greater minds may have a proper explanation.

Dan.

Last edited by Max Headroom; 24th February 2014 at 01:15 PM.
  Reply With Quote
Old 24th February 2014, 01:26 PM   #48536
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Vlad, decades ago, my associates built a 'break-in box' with an approximately 700Hz square wave. We found it satisfactory also, and easier on the amp. Your explanation of WHY 'break-in' works is what we believe to be true also. I have even offered 'evidence' here, but to no avail.
  Reply With Quote
Old 24th February 2014, 01:44 PM   #48537
diyAudio Member
 
Max Headroom's Avatar
 
Join Date: Jan 2013
Location: West Australia, straight over the road from the beach, natural ambient sounds only.
Quote:
Originally Posted by john curl View Post
......I have even offered 'evidence' here, but to no avail.
Hello John, do you mind give your findings again.

Dan.
  Reply With Quote
Old 24th February 2014, 01:46 PM   #48538
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
I'm tempted.
  Reply With Quote
Old 24th February 2014, 01:51 PM   #48539
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
it is just too suspicious that "burn in" is Always an Audible Improvement

not likely if it were objective materials property changes causing real electrical circuit performance changes - at least some changes could be expected to go the "wrong" way, stablize at a less optimal state after burn in
  Reply With Quote
Old 24th February 2014, 02:11 PM   #48540
diyAudio Member
 
jneutron's Avatar
 
Join Date: Jan 2004
Location: away
Quote:
Originally Posted by john curl View Post
I have even offered 'evidence' here, but to no avail.
Odd that you choose to bracket the word evidence as..... 'evidence'.

It appears you also question the validity of it. edit: (scientific validity)

jn

Last edited by jneutron; 24th February 2014 at 02:39 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 09:12 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