Anyone bias by their amp by ear? Did my 5153 and JSX...

[glip22]

You can bias almost every amp with a simple multimeter, alittle "know how", and simple math. And if you want it alittle hotter or colder you can adjust it.

Absolutely. But, most people I see on this forum would end up dead or needing CPR.

 

[bananaladonpcp]

You can bias almost every amp with a simple multimeter, alittle "know how", and simple math. And if you want it alittle hotter or colder you can adjust it.

Absolutely. But, most people I see on this forum would end up dead or needing CPR.

dude +100 on that.

 

[rocknrolla]

And this is why I never want to buy a used amp.
Please people, use a bias meter.

 

[loudgtr]

I ordered a Compu Bias. It's taking a while to get here...

One thing I read online about the Compu is that you cant bias with a guitar plugged in...so setting it while playing is not doable I guess. I'll read the manual once I get to make sure.

This is true of any bias meter. Compu-Bias puts their indemnity in the manual. I have been using one of these for the last few years, without problems. The reason is that bias plug breaks the ground. If you have the amp cranked and happen to pop a tube because you biased it too hot, voltage can travel back through the amp input, instead of to the fuse - to the guitar and to the strings and give you a hell of a jolt. You will look like Don King.

That said, you don't have to bias out of safe range. You don't even have to play the guitar while biasing to get peak performance. If you will give the amp a bit of volume with the bias meter hooked up, nothing plugged in, keep adjusting it up until you start hearing some hiss, then back it off a little bit. Check the bias and see where you are at. You will probably be in the 80-90% range.

70% is too cold for most amps, but, it is safe for vendors. Depends too how close to screen voltage you are and tube selection.

Thanks Steve, was hoping someone would give up some info

Last question...when starting to bias, should ALL eq knobs be at 0 or just the volumes? Does it not matter what the eq knobs are set at? Thanks guys.

 

[steve_k]

I ordered a Compu Bias. It's taking a while to get here...

One thing I read online about the Compu is that you cant bias with a guitar plugged in...so setting it while playing is not doable I guess. I'll read the manual once I get to make sure.

This is true of any bias meter. Compu-Bias puts their indemnity in the manual. I have been using one of these for the last few years, without problems. The reason is that bias plug breaks the ground. If you have the amp cranked and happen to pop a tube because you biased it too hot, voltage can travel back through the amp input, instead of to the fuse - to the guitar and to the strings and give you a hell of a jolt. You will look like Don King.

That said, you don't have to bias out of safe range. You don't even have to play the guitar while biasing to get peak performance. If you will give the amp a bit of volume with the bias meter hooked up, nothing plugged in, keep adjusting it up until you start hearing some hiss, then back it off a little bit. Check the bias and see where you are at. You will probably be in the 80-90% range.

70% is too cold for most amps, but, it is safe for vendors. Depends too how close to screen voltage you are and tube selection.

Thanks Steve, was hoping someone would give up some info

Last question...when starting to bias, should ALL eq knobs be at 0 or just the volumes? Does it not matter what the eq knobs are set at? Thanks guys.

No, it doesn't matter.....just the MV.

You're welcome

 

[loudgtr]

I ordered a Compu Bias. It's taking a while to get here...

One thing I read online about the Compu is that you cant bias with a guitar plugged in...so setting it while playing is not doable I guess. I'll read the manual once I get to make sure.

This is true of any bias meter. Compu-Bias puts their indemnity in the manual. I have been using one of these for the last few years, without problems. The reason is that bias plug breaks the ground. If you have the amp cranked and happen to pop a tube because you biased it too hot, voltage can travel back through the amp input, instead of to the fuse - to the guitar and to the strings and give you a hell of a jolt. You will look like Don King.

That said, you don't have to bias out of safe range. You don't even have to play the guitar while biasing to get peak performance. If you will give the amp a bit of volume with the bias meter hooked up, nothing plugged in, keep adjusting it up until you start hearing some hiss, then back it off a little bit. Check the bias and see where you are at. You will probably be in the 80-90% range.

70% is too cold for most amps, but, it is safe for vendors. Depends too how close to screen voltage you are and tube selection.

Thanks Steve, was hoping someone would give up some info

Last question...when starting to bias, should ALL eq knobs be at 0 or just the volumes? Does it not matter what the eq knobs are set at? Thanks guys.

No, it doesn't matter.....just the MV.

You're welcome

Thanks again

I'll do my best to not end up looking like Don King