Magnetic Interactions - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

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
Reply
 
Thread Tools Search this Thread
Old 25th June 2002, 03:20 PM   #1
diyAudio Member
 
mrfeedback's Avatar
 
Join Date: Feb 2002
Location: Perth, Australia.
Default Magnetic Interactions

Hello All, I thought I should relate a recent observation.
My PC workstation is a corner table with monitor on the table-top, and a vertical rack with amplifier, 14" TV/monitor and Vcr mounted, and Boston Acoustics A40 6-1/2" 2 ways on either side.

The amplifier that I am currently using (I have plenty of choice in amps) is a classic 1964 Panasonic Am/Fm all tube reciever.
This on a thin steel shelf 3" above my PC monitor.

My observation is that the PC display is modulated (jumps around) by the stray power AND audio fields, and in sympathy with the audio, and according to audio level.

It seems that these stray fields are quite strong, and not to be disregarded when building tube amps.
Maybe this is a help for some.

Regards, Eric.
  Reply With Quote
Old 25th June 2002, 03:36 PM   #2
PassFan is offline PassFan  United States
diyAudio Member
 
Join Date: Aug 2001
Location: Central FL
Eric:
Thanks for the warning. My amp is in close proximity to my CPU though seperated by about 1 foot and a couple inches of wood. I have about 2 feet to the monitor. I havn't had any problems so far but I will bear this in mind for any future changes. One other thing though, my chassis are made out of solid oak and not metal boxes. Perhaps shielding has something to do with expanding the field. Something to think about. Thanks again.
  Reply With Quote
Old 26th June 2002, 05:56 PM   #3
dhaen is offline dhaen  Europe
diyAudio Moderator Emeritus
 
dhaen's Avatar
 
Join Date: Jun 2002
Location: U.K.
Default Really?

Eric,

Are you sure it's not acoustical/mechanical?
What I mean is that if you vibrate a scanned device (CRT monitor), it interferes with the visual perception of the scan.
If you don't believe me, try this trick:
Clean your teeth with an electric toothbrush while in front of your CRT monitor.
The display seems to jump about like mad!
Of course this trick is actually the reverse of my suggestion, (by vibrating the observer) but it illustrates my point.
  Reply With Quote
Old 26th June 2002, 06:22 PM   #4
diyAudio Member
 
mrfeedback's Avatar
 
Join Date: Feb 2002
Location: Perth, Australia.
Hi dhaen
It is definately magnetic coupling.
The display jitter is a bit like when degaussing, except with audio component, and level and distance related.
I was just bringing to attention the levels of the radiated magnetic fields.

Eric.
  Reply With Quote
Old 26th June 2002, 07:05 PM   #5
diyAudio Member
 
Gabevee's Avatar
 
Join Date: Feb 2002
Location: Richmond, VA.
The electron beam is very sensitive to stray magnetic fields of any kind, even that of earth, which is much smaller than the local fields created by the OPTs of a power amp. And yet degaussing is to remove the influence of the earths magnetic field.

My 2 cents.

Gabe
__________________
Gabe CGV Electronics
Home of the CGV-300B amplifier on a budget
  Reply With Quote
Old 26th June 2002, 09:24 PM   #6
dhaen is offline dhaen  Europe
diyAudio Moderator Emeritus
 
dhaen's Avatar
 
Join Date: Jun 2002
Location: U.K.
Ok Eric, I conceed.

I was just a little surprised at the level from the distance you described. But now that you detail the purity/ landing distortion as well as the registration error, you must be right.
I've spent more than a little time with CRT's, and during my stay (15 years or so), we spent a lot of effort reducing this effect.

Thanks for the alert.
  Reply With Quote

Reply


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
Death Magnetic ak_47_boy Music 6 14th October 2008 01:12 PM
WTB: cd-pro magnetic clamp teleqc Swap Meet 0 13th February 2007 10:48 PM
Magnetic circuit hugobors Planars & Exotics 30 10th January 2006 12:22 AM
magnetic Pbassred Solid State 6 26th May 2004 12:14 PM


New To Site? Need Help?

All times are GMT. The time now is 05:47 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2