Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

Power trans coupling with speaker, causing hum
Power trans coupling with speaker, causing hum
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 15th January 2007, 02:59 AM   #1
slowpogo is offline slowpogo  United States
diyAudio Member
 
Join Date: Jan 2007
Default Power trans coupling with speaker, causing hum

I have a Fender Pro Jr tube amp that I've ugpraded/modified extensively. Hiss is way reduced, and there's no hum or buzz in the signal unless it's turned up all the way.

However, it seems the power transformer is coupling directly with the speaker, which is only about 6 inches away. In the 5-10 seconds before the tubes warm up and hiss fades in, I hear a quiet hum. Actually, it's there even if I unplug the speaker from the chassis.

I already relocated the output transformer and put a shield between it and the PT (small angled piece of sheet metal, thanks to Bill Machrone for that one), and that seems to have eliminated almost all output trans. related hum.

But how to shield the speaker from the power transformer? I'm sure the stock Pro Jr PT is just cheap, and getting a good replacement with a built-in shield would solve a lot of it. But is there any simpler solution, short of trying to construct some kind of massive homemade shield?

The hum is quiet and it's not a huge deal, but having come this far, I'd like to get rid of that last bit if at all possible...
  Reply With Quote

Reply


Power trans coupling with speaker, causing humHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Linear power supply causing mains hum at speaker cmhadley Power Supplies 5 18th April 2009 03:43 PM
Power Trans, 45V-0-45V pistoljoe Swap Meet 1 15th April 2008 11:39 AM
Power Trans Question cominup Parts 8 9th June 2005 09:06 PM
Power Trans. Sockets or not mashaffer Solid State 5 15th May 2005 04:18 PM
cap on speaker causing amp to cut out dvdwmth Chip Amps 1 12th September 2004 11:00 PM


New To Site? Need Help?

All times are GMT. The time now is 09:22 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio
Wiki