Can AC wires induce hum in output transformers? - 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 26th March 2009, 10:24 AM   #1
diyAudio Member
Rob11966's Avatar
Join Date: Jun 2007
Location: Australia
Default Can AC wires induce hum in output transformers?

Hi folks,

Can twisted AC wires (HV or heater) induce hum in (quality) transformers if they run close to the transformer? If so, how close is too close? I am not talking about the proximity or orientation of the power transformer to the output transformer but rather the AC secondary leads.

As a supplementary question, if induced hum is possible, would a 2mm aluminum plate between wires and transformer act as a shield?

Obviously, the simple solution is to keep the two separate but for various irritating reasons this is not easily possible with my current chassis.

Any input welcome. Thanks in advance.

  Reply With Quote
Old 26th March 2009, 10:37 AM   #2
diyAudio Member
analog_sa's Avatar
Join Date: Aug 2002
Location: Cascais
This induction is definitely not an issue at output levels. And the 2mm alu will have practically no effect.
  Reply With Quote
Old 26th March 2009, 04:50 PM   #3
Jeb-D. is offline Jeb-D.  United States
diyAudio Member
Jeb-D.'s Avatar
Join Date: Nov 2005
Location: SoCal
I'd only worry about it if the transformer is an open bracket interstage transformer that is being used in low level circuitry.

The twisted pair should be pretty resistant against causing this sort of thing.
  Reply With Quote
Old 26th March 2009, 05:06 PM   #4
diyAudio Member
Wavebourn's Avatar
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 26th March 2009, 05:15 PM   #5
diyAudio Member
Richard Ellis's Avatar
Join Date: Sep 2006
Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.
First off...Aluminum is a non-magnetic metal and will not "short out" a stray unwanted magnetic field.
If I recall, Morgan Jones made a notation to twist-per-inch of such lines. The twisting has a nulling effect for magnetic fields.
It would be a nice study of twisting 'rates' vs. field 'output'????
Seeing how some run these lines, I have the impression a "flanking manouver" with twisted pairs is a viable wiring technique.
Rather...not trying to do a shortest possible but a sweeping route thru the chassis...trying to maintain the longest distance between other wires. This of course will look kinda kooky with the twisted pairs floating thru the chassis toward their target.
I have the impression fields generated by twisted pairs is measured in millimeters. EG..3-7mm
_______________________________________________Ric k........
  Reply With Quote
Old 26th March 2009, 07:56 PM   #6
diyAudio Member
Rob11966's Avatar
Join Date: Jun 2007
Location: Australia
Thanks for the replies,

Normally I run all of the AC power lines away from any of the signal path, including the output transformers. Unfortunately the penetratrators for my power transformer leads ended up very close to my output transformer as I was forced to move my output transformers due to a problem with the original design of the chassis.

Anyhow, this is good news.

Cheers and thanks again.

  Reply With Quote
Old 26th March 2009, 11:18 PM   #7
pointy is offline pointy  United Kingdom
diyAudio Member
pointy's Avatar
Join Date: Mar 2009
it could be that the transfromers are acting on the ac wires. if so screen them.................................i think ?
  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
Difference between SE output transformer and push-pull output transformers hilbert_mostert Tubes / Valves 12 8th March 2009 05:10 PM
Help identifying a pair of output transformers and power transformers mjk130 Parts 3 30th January 2009 10:44 AM
Ferrite bed od the wires who goes to output transistors ? gaetan8888 Solid State 5 21st June 2007 06:50 PM
Conductors (I.C.'s, RCAs, internal wires, speaker wires) bigphil Parts 1 25th November 2005 06:47 PM
wires of output transformer are too thin! zxx123 Tubes / Valves 5 4th February 2005 10:18 AM

New To Site? Need Help?

All times are GMT. The time now is 01:04 AM.

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