Scratchy clicky noise coming from homemade 6L6 tube amp - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 15th June 2009, 02:52 PM   #1
Jim5150 is offline Jim5150  United Kingdom
diyAudio Member
Join Date: Jun 2009
Default Scratchy clicky noise coming from homemade 6L6 tube amp

Hi all ,

Got a bit of a problem and need some help, recently I built myself a 100W Power amp for use with my line 6 pedalboard. The amp has a 12Ax7 first stage to just increase the gain to line levels, a 12AT7 phase splitter and 4 6L6GC tubes and is based on a standard boogie type/ fender power amp design there are no tone controls just a volume which is controlled/coupled to the phase splitter. The problem I've got is that I get a scratchy type sound coming from it, the type of sound you get when you turn a dodgy pot or fiddle with dodgy lead or input but it's constant.
The sound is always there at the same volume no matter if the volume is down or way up. I've tried changing the the 12Ax7 and the AT7 but to no effect. Is there a resistor or a cap breaking down somewhere maybe a dodgy solder joint? If so does anybody have any ideas how to pinpoint it. Is there anything I should be focusing my intentions on. The bias supply for instance? I'm thinking that the Power section is at fault due to the fact that when the volume is at 0 the scratchy sound is still there and as the volume is controlled at the phase splitter section this rules out anything before. Anybody have any ideas.
Any help would be much appreciated?


  Reply With Quote
Old 15th June 2009, 05:09 PM   #2
diyAudio Member
Join Date: Oct 2004
Location: Maui, Hawai'i, USA
Clean the tube pins and sockets.

  Reply With Quote
Old 15th June 2009, 07:40 PM   #3
m6tt is offline m6tt  United States
diyAudio Member
Join Date: Aug 2007
Check bias, limit bandwidth (i.e. use grid stoppers), and clean as mentioned. Sometimes it's RF coupling from various stuff like motors, other times it's cathode noise from too high current, or of course spurious resistances from dirty sockets.
  Reply With Quote
Old 16th June 2009, 04:45 AM   #4
kevinkr is offline kevinkr  United States
diyAudio Moderator
kevinkr's Avatar
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
How about a schematic and a few pictures of your project as these might provide some clues in order to take a shot in the dark at what ails this thing.
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
  Reply With Quote
Old 25th June 2009, 10:53 AM   #5
Jim5150 is offline Jim5150  United Kingdom
diyAudio Member
Join Date: Jun 2009
Hi Guys , I cleaned the tube sockets with some alcohol type cleaner and although the sound hasn't completely dissapeared it's better and doesn't bother me anymore . So thanks for that.

Will post some photo's and some hand drawn schematics when I get a chance. As although the amp is working the sound is not quite what I want , so I may start a new thread reviewing my design and what I can do to improve the sound quality etc...

But thanks all for your help

Much appreciated

  Reply With Quote


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
Homemade Vacuum Tube dhaen Tubes / Valves 50 13th July 2011 05:48 PM
Why does my tube amp make a scratchy, popping sound? longdrive55 Tubes / Valves 12 11th August 2009 06:48 PM
Strange noise coming from MTX Thunder1004 amplifier fastblackcar94 Car Audio 1 17th November 2006 09:17 PM
scratchy staticy noise MrGuitardeath Chip Amps 1 23rd August 2004 09:22 PM
scratchy staticy noise MrGuitardeath Solid State 1 23rd August 2004 08:42 PM

New To Site? Need Help?

All times are GMT. The time now is 09:27 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2