symptom of a dying (gain) tube - 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 12th March 2012, 02:19 PM   #1
diyAudio Member
Join Date: Sep 2009
Location: seoul
Default symptom of a dying (gain) tube

what are the symptoms of an overaged tube in a preamp circuit? is it diminished bass/mid? i think i have some tubes that need changing.
  Reply With Quote
Old 12th March 2012, 02:51 PM   #2
diyAudio Member
Frank Berry's Avatar
Join Date: Sep 2003
Location: Midland, Michigan
It sounds more like a capacitor that is changing value.
As a tube ages, the emission will decrease. The effect will be lower gain and/or the early onset of clipping at high levels.
  Reply With Quote
Old 12th March 2012, 03:12 PM   #3
diyAudio Member
Join Date: Sep 2009
Location: seoul
i should mention that the gain is also lower. it takes about 3 times the turn of the volume that is usually required to reach the desired listening level.

the whole component is fairly new and the caps should be well within their lifespan.

Last edited by PreSapian; 12th March 2012 at 03:17 PM.
  Reply With Quote
Old 12th March 2012, 03:33 PM   #4
diyAudio Member
Osvaldo de Banfield's Avatar
Join Date: Dec 2011
Location: Barrio Garay,Almirante Brown, Buenos Aires, Argentina
May be that the +B is too low because of a bad cap or a false contact in the heaters rail so the tubes take more time to get normal cathode temperature.
Osvaldo F. Zappacosta. Electronic Engineer UTN FRA from 2001.
Argentine Ham Radio LW1DSE since 1987.
  Reply With Quote
Old 12th March 2012, 05:14 PM   #5
DF96 is offline DF96  England
diyAudio Member
Join Date: May 2007
You might get more distortion at levels below clipping. It is conceivable that your ears may perceive this as a frequency response problem, but it isn't.
  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
Dying breeds 503Timber The Lounge 0 31st May 2011 03:11 PM
opinion on cd700 cd-mecha error/symptom anton-sa Car Audio 0 28th August 2008 04:04 PM
help! EL84's dying buliwyf Tubes / Valves 5 23rd October 2005 05:31 PM
Symptom Diagnosis please? panos29 Multi-Way 12 18th April 2003 04:51 PM
Iron ( steel) dying Koy Solid State 6 28th August 2001 02:24 PM

New To Site? Need Help?

All times are GMT. The time now is 01:40 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