Peavey Classic 30 - Squeal - diyAudio
Go Back   Home > Forums > Live Sound > Instruments and Amps
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Instruments and Amps Everything that makes music, Especially including instrument amps.

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 8th February 2010, 02:37 PM   #1
diyAudio Member
Join Date: Feb 2010
Default Peavey Classic 30 - Squeal

I have just bought my first tube amp recently, and not knowing much about them, i would like some advice on a problem i am having.

At first it was fine and i was able to play it with no problems, but recently there has been a squealing noise when i put it on. It sometimes stops after being on for a couple of minutes but 90% of the time it doesnt stop and i have to turn it off.

I notice when i tap the silver part where the volume knobs are (just above where the tubes are) that it has a break in between each squeal.

I have never changed the tubes, as i was told they were brand new when i bought it (2nd hand) and ive had the amp for about 6 months.

Would the best action be to change ALL of the tubes at once and see if that rectifies the problem?
Or, is there a way i can isolate it to see which tube it is that needs to be replaced?

.... if it is in fact as easy as changing the tubes, could it be a different problem?

I have searched the forum, and although there are threads on the 'squeal' from an amp, most of what i read was the squeal from other members amps occurs at a higher volume. The squeal in mine occurs even when all the volume levels are turned to zero.

Kinda hoping someone can reassure this complete newbie lol.
Thanks in advance for any suggestions you may have.
  Reply With Quote
Old 10th February 2010, 06:42 PM   #2
diyAudio Member
Join Date: Feb 2010
Umm, well ive bought tubes anyway, hopefully they'll be here by the weekend.... and hopefully they'll be what the problem is.

Just giving this a bump incase anyone has an opinion on what else it could be. (sorry if bumping is frowned up here)
  Reply With Quote
Old 10th February 2010, 09:49 PM   #3
diyAudio Member
Rod Coleman's Avatar
Join Date: Jul 2004
Location: Warwickshire UK
Tubes (especially 12AX7 preamp tubes) are quite likely, especially if it responds to tapping/knocking.

Another really frequent problem with Peavey (& Fender) is the power supply capacitors. The grey IC (Illinois) axial type are often used, and these can have a short life (I have seen as bad as 5 years).

Not a really high priced job, but it's best to have them all renewed, if any are bad. If they are 10 years old, they will be sounding bad, as well. Well-chosen new power caps sound better than a set of new valves, in many amps. Get your tech to fit Nichicon VX series 22uF/450v (they can take 500v unloaded) in the preamp section, and Panasonic TSHA (or TSUP) in the position after the rectifier.

Good luck!
  Reply With Quote
Old 11th February 2010, 02:06 AM   #4
diyAudio Member
Join Date: Feb 2010
Used, right? Get some spray cleaner, no lube. Remove all tubes. Spray all tube connections and all pots...turning the pot switch'es and spraying again to really clean. Get some spray lube for pots and pots only. Check/clean tube pins ( be careful ). Check all internal wiring for breaks or looseness. Normal caveats apply for electrical hazards. If you don't know what you're doing, take it to someone that does.
  Reply With Quote
Old 11th February 2010, 06:29 PM   #5
Enzo is offline Enzo  United States
diyAudio Member
Join Date: Sep 2004
Location: Lansing, Michigan
Isolate the problem. Turn it on, get it to squeal.

Now, do ANy controls have ANY effect on the noise? (That helps localize which part of the circuit is doing this)

Tap on each tube, going down the row. DO any respond to the tapping?

GO down the row and firmly grasp each tube and hold it. Use a rag or glove if they are too hot for you. Does gripping a tube have any effect. (We are looking for microphonic tubes)

SInce tapping on the chassis affects the noise, then if it is not a tube (most likely it is a tube) there is a loose connection somewhere inside.
  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
Peavey Classic 60/60 bias mod advice RIC Instruments and Amps 7 4th November 2013 10:34 PM
ARC Classic 30 problem TonyE Tubes / Valves 3 2nd January 2007 11:05 AM
need schematic: peavey minx bass amp 30 watts elementx Instruments and Amps 1 12th July 2006 11:59 PM
squeal in amplifier n0plb Tubes / Valves 5 5th July 2005 11:16 AM
can I tone control the Peavey Classic 60/60 RIC Instruments and Amps 2 24th March 2005 04:27 AM

New To Site? Need Help?

All times are GMT. The time now is 12:19 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