#1
Hey, recently put new power tubes in my carvin and I'm experiencing slight volume spikes after about 10 minutes of play on the lead channel. Will getting them biased fix this up, and will playing at lower levels fix this until then?
"Don't panic, everything is falling neatly out of order"
- Douglas Adams
#2
When was it that people started believing that you didn't need to bias power tubes when you swapped them out? It's not an option to maximize performance, it's a necessity to ensure that your amp is running under safe conditions.

Volume fluctuations can occur when your power tubes are dying. I'm not suggesting anything, but generally, if the tubes you stuck in there draw more plate current than whatever you had in there before, and you didn't rebias, it would not be out of the question that those tubes could be on the way out. Especially if you've been playing the amp at higher volumes.
#3
Quote by al112987
When was it that people started believing that you didn't need to bias power tubes when you swapped them out? It's not an option to maximize performance, it's a necessity to ensure that your amp is running under safe conditions.

Volume fluctuations can occur when your power tubes are dying. I'm not suggesting anything, but generally, if the tubes you stuck in there draw more plate current than whatever you had in there before, and you didn't rebias, it would not be out of the question that those tubes could be on the way out. Especially if you've been playing the amp at higher volumes.


Look, I've heard from a tech that it prolongs the life of the tubes, and depends on how hot or how the amp sounds. I just wanted to play the thing. So I played with them for a good while, fresh and unbiased. He also said that some blues players prefer the sound of unbiased power tubes to biased power tubes. He didn't make it out to be life or death on the case whether to do it or not, although I do understand it's importance.

So you're telling me that these power tubes, that haven't been used for more than 7 hours are about to die because I didn't bias them all? Is that seriously what could be happening?
"Don't panic, everything is falling neatly out of order"
- Douglas Adams
#4
Quote by Otnip
Look, I've heard from a tech that it prolongs the life of the tubes, and depends on how hot or how the amp sounds. I just wanted to play the thing. So I played with them for a good while, fresh and unbiased. He also said that some blues players prefer the sound of unbiased power tubes to biased power tubes. He didn't make it out to be life or death on the case whether to do it or not, although I do understand it's importance.

This is going to sound mean but your tech is an idiot and you need to start taking your amp to a new one. Especially if he's feeding you BS like this. Biasing your amp is setting a safe operating range for the tubes. You bias them too cold you get crossover distortion, you bias them too hot, they can die on you within minutes. For a tech, this blues players comment was an absolutely idiotic thing to say as playing with unbiased tubes can lead to many outcomes depending on the tubes. Who knows if a set of tubes you stick in an amp will run hot or cold? You can't tell until you measure the bias.

So you're telling me that these power tubes, that haven't been used for more than 7 hours are about to die because I didn't bias them all? Is that seriously what could be happening?

It is not out of the question, especially if your tubes are "hot" and draw a lot of plate current. I've burned out power tubes in less time than 7 hours. I've had tubes redplate on me in less than 10 minutes of playing time when they were biased too hot.
Last edited by al112987 at Jan 27, 2009,
#5


Please go take your amp to get your tubes biased, because you're obviously don't know enough about amps to bias them yourself. Having tubes biased to hot is can shorten the life of your tubes. And having them biased to cold will make your amp sound bad. You have to find the sweet spot on your amp. Are you even using a matched quad? Where did you get your tubes from?
Quote by doggy_hat
This chick that looked like shrek ****ed me while I was passed out on xanax. I screamed when I woke up.
#6
Quote by BleedDeathMetal


Please go take your amp to get your tubes biased, because you're obviously don't know enough about amps to bias them yourself. Having tubes biased to hot is can shorten the life of your tubes. And having them biased to cold will make your amp sound bad. You have to find the sweet spot on your amp. Are you even using a matched quad? Where did you get your tubes from?


I'm using a matched quad, or at least I think I am, I'm using two matched sets of EH El34's I got from knostubes. I'm far too afraid of screwing up the process or killing myself to bias them with my current experience (and bad luck) with tube amps so yes, time to take it to a new tech it seems...

And it seems like it's time for even more tubes... Great...

Thanks for the insight guys. If anyone has any other ideas, post 'em please.
"Don't panic, everything is falling neatly out of order"
- Douglas Adams
#7
Quote by Otnip
I'm using a matched quad, or at least I think I am, I'm using two matched sets of EH El34's I got from knostubes. I'm far too afraid of screwing up the process or killing myself to bias them with my current experience (and bad luck) with tube amps so yes, time to take it to a new tech it seems...

And it seems like it's time for even more tubes... Great...

Thanks for the insight guys. If anyone has any other ideas, post 'em please.

It's always best to get a second opinion. I would recommend not playing the amp until you bias it. Don't make the same mistake I did and break the amp due to stupidity. It ended up costing me more to get mine fixed then it would've for a tube change. Just be careful.

BTW- Two pairs of two matched tubes =/= a matched quad. This is imperative to make sure that your tubes are running at the same level. I would have your tech check them out before he installs them. There is a margin of error allowed, but the smaller the better.
Quote by doggy_hat
This chick that looked like shrek ****ed me while I was passed out on xanax. I screamed when I woke up.
Last edited by BleedDeathMetal at Jan 27, 2009,
#8
Quote by BleedDeathMetal
It's always best to get a second opinion. I would recommend not playing the amp until you bias it. Don't make the same mistake I did and break the amp due to stupidity. It ended up costing me more to get mine fixed then it would've for a tube change. Just be careful.

BTW- Two pairs of two matched tubes =/= a matched quad. This is imperative to make sure that your tubes are running at the same level. I would have your tech check them out before he installs them. There is a margin of error allowed, but the smaller the better.


So will he be able to tell if I destroyed my tubes or should I just get a new set of four? I only really have the money for preamp tubes and that was what I was about to buy until I did this...
"Don't panic, everything is falling neatly out of order"
- Douglas Adams
#9
Quote by Otnip
So will he be able to tell if I destroyed my tubes or should I just get a new set of four? I only really have the money for preamp tubes and that was what I was about to buy until I did this...

Preamp tubes last longer then power amp tubes. I would start with just power and then if your not happy add some pres. They are simple enough to do yourself. He should be able to tell you if your tubes are all right, and to be honest I'm sure they are. It just seems to me like your amp is biased cold.
Quote by doggy_hat
This chick that looked like shrek ****ed me while I was passed out on xanax. I screamed when I woke up.
#10
Quote by Otnip
So will he be able to tell if I destroyed my tubes or should I just get a new set of four? I only really have the money for preamp tubes and that was what I was about to buy until I did this...

You can't really tell a power tube is dying visually generally, but if it redplates, it's usually a good indication (the big gray plate in the center is glowing orange) that the tube is on it's way out.