Guitar Forums

Go Back   Guitar Forums > The Gear > Amplifiers

Reply
 
Thread Tools Display Modes
Old 02-10-2018, 03:54 PM   #1
grousehunter49
Senior Member
 
Join Date: Jan 2010
Location: NFLD/LARBADOR
Posts: 391
grousehunter49 Just getting started
Default Bad tube

When you own a amp that only has one tube.how do you tell when that tube is bad or not doing it,s job. Micro terror.
grousehunter49 is offline   Reply With Quote
Old 02-10-2018, 03:59 PM   #2
Seattle
Senior Member
 
Seattle's Avatar
 
Join Date: Nov 2015
Posts: 1,196
Seattle Just getting started Seattle Just getting started
Default

Quote:
Originally Posted by grousehunter49 View Post
When you own a amp that only has one tube.how do you tell when that tube is bad or not doing it,s job. Micro terror.
When you can't hear anything? Make sure it didn't just become unseated.
Seattle is online now   Reply With Quote
Old 02-10-2018, 04:31 PM   #3
KamaK
Retired
 
Join Date: Dec 2016
Location: East Coast
Posts: 250
KamaK Just getting started
Default

Some common modes of tube failure are:

1: Produces no sound
2: Sounds fine for a few mins, then starts to crackle.
3: Sounds fine for a minute, then starts to (make a sound like a) motorboat
4: Goes completely microphonic, and whistles.

My recommendation is that tube amp owners simply own two complete sets of tubes and an inexpensive multi-meter, and familiarize themselves with how to replace them. It's typically not a huge financial burden unless you're running a quad of 6550's or similar.

Tube amp owners should also obtain an "Uncle Doug" level of understanding their amp, especially when it comes to biasing.

https://www.youtube.com/watch?v=L3rRk3eSTnA
https://www.youtube.com/watch?v=w9B0Rhr_Y-E

Last edited by KamaK; 02-10-2018 at 04:42 PM.
KamaK is online now   Reply With Quote
Old 02-10-2018, 05:34 PM   #4
pdawg0
Senior Member
 
Join Date: Apr 2015
Location: TX and NY
Posts: 656
pdawg0 Just getting started
Default

^^^ Yep. What he said ^^^

Have spares, and understand how to replace them and set the bias, if needed.
pdawg0 is offline   Reply With Quote
Old 02-10-2018, 08:07 PM   #5
PKVeazey
Old Timer
 
PKVeazey's Avatar
 
Join Date: Jun 2017
Location: South Central Virginia
Posts: 892
PKVeazey Just getting started
Default

Waaayyyyy back when I rode a dinosaur to work, I had several tube amps. The first sign that a tube was going soft(getting gassy), I would notice the high frequencies weren't quite what they used to be. Then I'd notice that the amp wasn't quite as loud as it used to be. By that time, I'd be suspicious that something was wrong and I'd turn the amp one and wait about a full minute and tap the tubes with my fingernail to see if they were microphonic. If I heard something that sounded like, "Tink, Tink, Tink", coming out of the speaker, I say, "Oh, Crap!" Then I'd replace the offending tube. Sometimes I'd wobble the tube around in the socket to burnish the pins and that would cure the problem. Then, of course there is the old standard of the amp sounding like WW3 was going on and I'd retube the whole amp.
__________________
Always B natural, Sometimes B sharp, Never B flat.
PKVeazey is offline   Reply With Quote
Old 02-12-2018, 12:25 AM   #6
Hi Hat
Senior Member
 
Hi Hat's Avatar
 
Join Date: Oct 2014
Location: By the snare drum
Posts: 2,579
Hi Hat The Oven's On But Nothing's Cooking Hi Hat The Oven's On But Nothing's Cooking
Default

I don't even know where to find a tube tester these days.
Hi Hat is offline   Reply With Quote
Old 02-12-2018, 01:03 AM   #7
GarethB
Member
 
Join Date: Apr 2016
Posts: 47
GarethB Just getting started
Default

Unless you can find someone who has an old tube tester, the only one I know of that's still being made is from Orange, but they cost US$500 new.

https://www.amazon.com/Orange-VT1000.../dp/B00BOU7QC0
GarethB is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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


All times are GMT. The time now is 03:57 AM.


Powered by vBulletin® Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Guitar Competition | Piano Lessons