Is there an ez way to tell a bad tube from a good tube?

[lhrocker]

As the title says, how can I tell if one of my tubes in my amp is bad and then which one?

[elcid]

Leave your wallet next to it then leave the room. If your wallet is there when you come back, you have a good one.

[satchboogeyman]

swap em out one at a time. check out eurotubes website he has some tips there.

[jb4674]

look at the tubes and if one's totally smoked up inside, then it's bad. Use the same logic you would use when a bulb's burned out.

Jimmy

[ChopTart]

If your amp comes with a tube task-chart, you can tell which tubes perform which jobs in the amp, and narrow it down to (usually) one or two. Then, like said before, it's just a matter of switching and listening.

[Paul_R]

What are the symptoms that make you think you have a bad tube(s)?

You should replace tubes in your amp when you start to notice changes in the sound quality. I took my Marshall 30th Anniversary (Blue Tolex Thank You! ) for a check up and it had tubes replaced due to "not top notch sound." What a difference in the sound with new tubes! I fell MORE in love with it.

Anyways, bad tubes can create a dull sound. The gain of the amplifier can decrease noticably.

The best and easy way to identify a bad tube from a good tube is to use a tube tester (For example: http://maximatcher.com/operate.htm#plate). Most don't have one. I have one on my want list but they're expensive.

Hope that helps.

Paul

[RG462]

try knocking on each tube with the amp turned on. if it makes a crazy sound, most likely its a bad tube.

[ChopTart]

Originally Posted by RG462

try knocking on each tube with the amp turned on. if it makes a crazy sound, most likely its a bad tube.

But be sure to be very gentle!

A light tap with a chopstick or a pencil should do.

[bpd111]

How about if it makes a fizzy sound, pops, blows the fuse, emits a flash of light, smokes, and then makes no sound at all?

[Brando Clean]

If the tube once had a mirrored or silver tip where the glass has a wick and now it is white or clear, the vacuum is gone. The tube has a leak.

"try knocking on each tube with the amp turned on. if it makes a crazy sound, most likely its a bad tube."

Sort of true, but not always. Some tubes are just microphonic. All are to some extent. That is why dildoes sell fancy rubber bands on Skibay to prevent microphonics.

[sleepyone]

One power tube in my amp looks like a burnt bulb...some people told me that is something common with tubes and that it doesn't mean it's ***ked up...that when a tube really burns out it turns incandescent red and almost "explodes" sort of speaking...please don't laugh at me (hehehe) I'm sure you'll know the right answer

[jemaholic]

bad ones are usually in and out of jail.
good ones you find in church alot.

sorry- had to.
-jemaholic