JCM Build - Hum and Crackle - 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 23rd January 2012, 06:13 PM   #1
diyAudio Member
Join Date: Apr 2011
Default JCM Build - Hum and Crackle


I've had my JCM 800 2204 build up and running for a while now! - However, The Amp has a low frequency hum which you can really hear when you turn up the volume! - But more annoyingly, every now and then it crackles... It also crackles when I tap (Not particularly hard but not soft) on the top of the amp! :S

The Hum could be because I haven't grounded the C.T of the heater windings... I wasn't too sure about grounding them as I'm using the C.T of the heaters to make up 6.3VAC across the valve (One tap is 6.3, so I had to use the C.T otherwise I would have 12.6VAC to the valve heater pins!).
Will grounding the C.T have any affect on anything other than getting rid of the hum? Click the image to open in full size.

I have no idea of what could cause the crackle so any ideas on that would be great! Click the image to open in full size.

Many Thanks in advance! Click the image to open in full size.
  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
JCM Build - Voltage problem! shunt94 Instruments and Amps 6 16th November 2011 06:58 AM
does some know how to build a 60hz hum Eliminator which stops the 60 hz hum?? prorms Solid State 21 13th August 2011 07:26 PM
jcm 800 preamp? thefruitgnome Instruments and Amps 4 1st April 2010 06:09 PM
Sub plate amp hum/crackle GhettoSQ Solid State 3 15th February 2007 03:35 PM
marshall jcm hifi? honsten Instruments and Amps 0 9th May 2004 01:41 PM

New To Site? Need Help?

All times are GMT. The time now is 08:41 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