Why a sudden distortion in treble of this SET amplifier? - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 2nd May 2012, 10:19 PM   #1
diyAudio Member
 
Join Date: Apr 2010
Default Why a sudden distortion in treble of this SET amplifier?

I have had this very sophisticated SET amplifier with 520B valves on the output for a few years now; recently I noticed a unusual distortion between 5k and 12k that was not present before. Neither is the distortion in three other amps I have so I don't think it's related to the AC line. Nothing else change in the amp's sound that I could tell.

If it is a bad part in the amp, what are the first suspects? cap, resistor, tube?
  Reply With Quote
Old 3rd May 2012, 12:29 AM   #2
diyAudio Member
 
Join Date: Sep 2004
Location: North Carolina,
Are you sure it is not the tubes.
I wish I could help try and post this ? on diytube.com
maybe those guys can help.
  Reply With Quote
Old 3rd May 2012, 02:26 AM   #3
tim614 is offline tim614  United States
diyAudio Member
 
tim614's Avatar
 
Join Date: Jun 2008
power supply caps, im guessing.
i had the same thing happen to one of my amp, it turn out to be bad power supply caps.
__________________
Tim
" perfect imperfection "
  Reply With Quote
Old 3rd May 2012, 02:28 AM   #4
tim614 is offline tim614  United States
diyAudio Member
 
tim614's Avatar
 
Join Date: Jun 2008
what brand is this amp?
__________________
Tim
" perfect imperfection "
  Reply With Quote
Old 3rd May 2012, 06:17 AM   #5
diyAudio Member
 
Join Date: Apr 2010
I have tried different tubes and the problem persists.

The amp was made in Denmark by J. Nielsen. But the designer has no idea what could be the cause.

I also thought it could be the PS caps, especially considering the number of 150uF caps he uses in series for the B+ filtering. I think there are 24 of those caps in series... Checking that will be a major work.
  Reply With Quote
Old 4th May 2012, 05:50 AM   #6
M Gregg is offline M Gregg  United Kingdom
diyAudio Member
 
M Gregg's Avatar
 
Join Date: Jun 2010
Location: UK
Quote:
Originally Posted by spartan View Post
I have tried different tubes and the problem persists.

The amp was made in Denmark by J. Nielsen. But the designer has no idea what could be the cause.

I also thought it could be the PS caps, especially considering the number of 150uF caps he uses in series for the B+ filtering. I think there are 24 of those caps in series... Checking that will be a major work.
Just a thought,

Have you checked the bias of the O/P tubes? also bias voltage and B+ supply voltage + ripple? Can you direct us to a schematic it might be easier to give some more information..

Regards
M. Gregg
__________________
What is the sound of one hand clapping?
  Reply With Quote
Old 4th May 2012, 06:00 AM   #7
diyAudio Member
 
Join Date: Apr 2010
I haven't. Can you tell me how to do that?
  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


Similar Threads
Thread Thread Starter Forum Replies Last Post
HP 339A Distortion Set cowboy99 Swap Meet 9 31st May 2014 05:27 AM
need help on treble distortion with my EAR834p phono bigpandahk Tubes / Valves 8 26th December 2010 02:54 PM
RADFORD - Low Distortion Measuring Set TomWaits Equipment & Tools 15 22nd November 2007 04:17 PM
simple guitar preamp with bass treble distortion garydmd Chip Amps 0 7th April 2007 03:27 AM
Iron set for Paraglow (2A3) SET amplifier Alain Favret Swap Meet 1 19th March 2004 06:23 AM


New To Site? Need Help?

All times are GMT. The time now is 01:55 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