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Tubes, how to know when they are near the end ?

Chun13

Member
Messages
156
Hello to everybody ! Sorry for this question but my D13 sometimes has some wierd sounds in it and I was wondering if it was the tubes going microphonic?

How to know when a tube is near it's end ? Do I nead a multimeter or can I tell just by looking at it ?
 

Timbre Wolf

>thermionic<
Platinum Supporting Member
Messages
10,447
A ringing sound, that is not associated with what you play, indicates microphonics. Preamp tubes often get some random scratching, popping or fizzing sounds when they're failing, as well. Can you describe your weird sounds?

- Thom
 

Blue Strat

Member
Messages
30,241
Hello to everybody ! Sorry for this question but my D13 sometimes has some wierd sounds in it and I was wondering if it was the tubes going microphonic?

How to know when a tube is near it's end ? Do I nead a multimeter or can I tell just by looking at it ?
Have spares of everything (you're going to need them eventually). Periodically swap in the new tubes and see if you notice a difference.

If your /13 uses a 5879, that's a likely culprit of microphonics. Tap lightly on it with the amp turned on. If it makes a ringing sound, that's the one.
 

Chun13

Member
Messages
156
Well, sometimes it works with no parasite sounds at all, but sometimes there's a slight buzz going on and off periodically. It's really random, sometimes it'll just stay for a few minutes then it's gone, sometimes no sound at all.

A ringing sound, that is not associated with what you play, indicates microphonics. Preamp tubes often get some random scratching, popping or fizzing sounds when they're failing, as well. Can you describe your weird sounds?

- Thom
 

Mooncusser

Member
Messages
2,207
As far as I am aware, power tubes go slowly, become microphonic at times, and has intermittent volume loss or low end loss.
BUT....this happens at a gradual rate usually, so it's one of those things where you eventually pick up on something new, because no one nows your amps nature better than you since you use it day in and out.
You can invest in a moderatley priced Hickock to have on hand...I think they are invaluable, as they test for most every tube you would use.
I hope that helps out a bit...
All the best,
Mass
 

Blue Strat

Member
Messages
30,241
Well, sometimes it works with no parasite sounds at all, but sometimes there's a slight buzz going on and off periodically. It's really random, sometimes it'll just stay for a few minutes then it's gone, sometimes no sound at all.
If you haven't already, try tapping lightly on each tube while the amp is running.

Also, clean all tube pins and tube sockets with some electronic spray cleaner. You'd be amazed at how many amps can be fixed by doing this.

The bottom line is, without doing some trial and error, no one can tell you what's up with your amp over the internet.
 

Timbre Wolf

>thermionic<
Platinum Supporting Member
Messages
10,447
The bottom line is, without doing some trial and error, no one can tell you what's up with your amp over the internet.
+1

But there are some great suggestions to try out. This is why it is a good thing to learn how to trouble-shoot your amp yourself. Same as learning how to do the setup on your own guitar - fine things to learn.

- Thom
 






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