Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki 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

OPTs causing crosstalk?
OPTs causing crosstalk?
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 28th November 2006, 02:43 PM   #1
blacklight is offline blacklight  Finland
diyAudio Member
Join Date: Feb 2006
Location: you tell me
Default OPTs causing crosstalk?

A simple, stupid question: Can channel crosstalk be caused by a stray magnetic field from one OTP to another, if they're relatively close to each other like in a stereo amp?
  Reply With Quote
Old 28th November 2006, 09:24 PM   #2
HollowState is offline HollowState  United States
diyAudio Member
HollowState's Avatar
Join Date: Aug 2006
Location: Taxland, New Jersey
I suppose it would be possible if they were operating at a very high level and they were positioned just right and unshielded. However, I think it very unlikley. At least I've never experienced it or heard of such a case.

Crosstalk usually comes from low level circuits which are much more susceptible to it through improper lead dress, parts placement or poor circuit board layout. Also, from a stereo amplifier that uses a common power supply that is not sufficiently isolated or perhaps somehow faulty.

  Reply With Quote
Old 28th November 2006, 10:49 PM   #3
Tubelab_com is offline Tubelab_com  United States
diyAudio Member
Tubelab_com's Avatar
Join Date: Jul 2005
Location: West Virginia panhandle
It is possible, and I have heard it happen, but I don't think that it is a problem in the real world.

Below is a picture of my TubelabSE amp. I put all 3 transformers in a row right next to each other (dumb!). This amp worked fine with my 86db 7 speakers with a 7 inch woofer (limited bass response). When I took it to a friends house who had big horns that are 101 db efficient I heard HUMMMMMMMM. The hum was worse before the rectifier warmed up (no current in the OPT's). I have since rotated the power transformer 90 degrees and no more hum.

As for the crosstalk, I have performed the following test a few years back. One channel driven to full power (music) into an 8 ohm resistor. The other channel with its input shorted into headphones. There was some very faint bass sounds indicating some crosstalk. In an atempt to determine if it was electrical, I pulled the input tube for the silent channel. The sounds diminnished indicating some electrical crostalk. I then pulled the output tube, and much to my surprise the sound increased. It was still very faint into headphones, so it would never be heard through speakers. The sound was all low frequency stuff, I could make out the kick drum beat but nothing else.

This told me that SE OPT's are more succeptable to magnetic fields when there is no current flowing. I experimented with other OPT's and they all do this to some degree. These are custom Electra-Prints. The magnetic field radiated from an SE OPT goes up when it hits saturation. I have seen the effects in a neighboring OPT on an oscilloscope.
Attached Images
File Type: jpg nx483.jpg (65.9 KB, 90 views)
Tubelab, it's 5 year mission. To explore strange new tubes, to seek out new circuits and topologies, to boldly go where no tube has gone before......
  Reply With Quote


OPTs causing crosstalk?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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
OPT Grounding / Crosstalk draperphoto Tubes / Valves 0 5th October 2008 12:07 AM
Crosstalk cancellation Prune Digital Source 10 19th January 2006 02:19 PM
PSRR and Crosstalk dgardner Solid State 4 20th June 2005 01:09 PM
A question on crosstalk sardonx Solid State 6 21st June 2004 11:45 PM
Crosstalk cancellation Prune Everything Else 0 31st March 2004 12:11 PM

New To Site? Need Help?

All times are GMT. The time now is 02:05 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio