When power tubes start making a popping sound does that mean they're arcing?

[EADGBE]

Or could it be something else?

 

[PushedGlass]

You mean popping acoustically, from the tube?

 

[Sweetfinger]

Look at the tube while it is making the sound. Generally, you will quite clearly see if any bad things are happening.

 

[EADGBE]

You mean popping acoustically, from the tube?

No I mean more like an electrical discharging or shorting kind of pop.

 

[zenas]

That could be alot of things. Knowing what the amp is, it's age and what's been done to it may help.

 

[EADGBE]

Well the amp is a Marshall TSL602 combo. The tubes were GT labeled Svetlana EL34s. After about eight years they started making a popping sound. I couldn't see anything from the tubes themselves. Anyway I've already tossed the tubes. And I've ordered some new ones. But I was just wondering what was causing the popping sound? On average when a power tube gets old what is the first thing that breaks?

 

[J M Fahey]

The sockets might be popping.
They get the exact same voltage as tubes.

Open the chassis, have it upside down (just don't touch anything inside) and look at it (even play) in a darkened room.

You should see the faint bluish sparks , or the sparking might be internal.

In general, 8 y.o. tubes rather than "sparky" (although not impossible) simply lose emission and are worn, weak.

 

[mark norwine]

I'm confused

Is this sound coming from the speaker (an amplified noise) or is it coming from a component in the amp?

 

[stratified]

I was wondering the same thing.
I think the OP means there's a popping sound coming from the speaker and is assuming it's the output tubes causing it. We're still not sure why this assumption is being made.


There are many things that can cause a popping sound to come from the speaker and yes, output tube arcing is one of them.

A preamp plate load resistor that has cracked can cause the symptom.
A leaky capacitor can cause the symptom.
A failing rectifier can cause the symptom.
Etc.

 

[Jeff Gehring]

At least it's not power tube arching...

 

[zenas]

I wouldn't have tossed the tubes until l knew they were bad. Did a 60ish year old amp a while back. Guy says "it probably just need new tubes".
Didn't need any new tubes. Capacitors yes but no tubes.

Well I guess we wait and see what the new tubes do now.

 

[EADGBE]

Well the spares didn't make the same loud predictable popping sounds via the speakers. I tossed them so I wouldn't get them mixed up with the others. I bought them in 2004. So it was time for a change. They lasted much longer than I thought they would. By comparison the Electro-Harmonix's I used previously only lasted about three years before they developed what looked like a gas leak.

 

[mark norwine]

so we ARE talking about "sound from the speaker", correct?

Does it sound like bacon frying? That's plate load resistors.

It would still be nice to know what make/model amp we're talking about....

 

[EADGBE]

The amp is a Marshall TSL602 combo. There was no bacon frying sound. Just a very audible pop sound that occurred about eight minutes after turning the amp on. If I continued to play the amp it would occur a little more frequently. But I would stop playing and turn it off as I didn't want to harm the amp. It was only with these tubes.

 

[zenas]

Oh ok you did try other tubes first. Sounded like you just tossed them and were waiting for replacements.

 

[EADGBE]

Oh ok you did try other tubes first. Sounded like you just tossed them and were waiting for replacements.

The tubes that started popping were eight years old. They sounded great for many years. I replaced them and the popping sound went away. I was just wondering if the popping sound was evidence of arcing?

 

[J M Fahey]

Might very well be.
Confirmed by the new tubes working perfect.