Amp Bias, hotter or colder?

[griff]

Hey guys, firstly for you tube players, what do you normally have your amps biased at for the best tone (in your view)?
My amp apparently comes out of the factory biased on the cold side to preserve tube life, but sometimes I feel my amps tone can be a bit richer and dynamic so maybe a hotter bias will do some good.
What tone changes have you noticed, good or bad, with a hotter bias?
I don't mind replacing tubes more often with a hotter bias.

[sizzlingbadger]

Depends quite a bit on the amp. Are you using mostly pre-amp gain or power amp gain ? are you playing mainly clean ? how loud ? What amp is it ? etc...

[griff]

Yeah I guess. Half and Half on the preamp and power amp, some clean stuff but mainly overdriven, not much high gain. Usually 'Pub loud'. Jet City 20 watt. Great amp.

[calling card]

Only one I've adjusted has been a Fender twin, I checked the voltage when I got and it was way down low. Power tubes hardly made any heat, sounded a little weak too. As the voltage climbed I could hear it stirring into action, like steam in a boiler. Set to factory spec and sounding like I'd imagine a twin ought to. This thing does make quite a bit of heat after an hour of running.
I'd suggest a check and correct it to spec if necessary but would be cautious with sneaking it up beyond factory setting.
The voltage is so small you need a very good meter too.

[sizzlingbadger]

I would just make sure its biased to spec, those Jet City's sound great standard, they are not renowned for their clean tones

[griff]

I would just make sure its biased to spec, those Jet City's sound great standard, they are not renowned for their clean tones

They are biased cold out of the factory.
A guy Mark Marshall was saying on a FB forum earlier today (he mods these amps all the time) is to try and Bias the power tubes as hot as possible and back it off a bit (The redplate method). He said JJ's will last over 2 years even though they run quite hot.
Yeah clean tones aren't fender clean by any means, but with a bit of delay and low pre gain I can get quite a passable Sultans Of Swing solo tone.

[NippleWrestler]

Most amps come cold biased from the factory. They might be sitting on the shop floor for a long time being tested so the tubes need to last a while.

Everyone except Crate ships this way in my experience, who bias the tubes mightily hot.

I keep my bias at around 60-70% but it depends on the amp... my custom Bigfoot amp had the bias at 2ma and roars like a bastard. It can go up to 40ma comfortably but I've never wanted to go above 16ma (w/ EL34s). My Laney AOR 30 I keep pretty hot because it's a small amp and I like the extra grunt.

[sizzlingbadger]

I would just make sure its biased to spec, those Jet City's sound great standard, they are not renowned for their clean tones

They are biased cold out of the factory.
A guy Mark Marshall was saying on a FB forum earlier today (he mods these amps all the time) is to try and Bias the power valves as hot as possible and back it off a bit (The redplate method). He said JJ's will last over 2 years even though they run quite hot.
Yeah clean tones aren't fender clean by any means, but with a bit of delay and low pre gain I can get quite a passable Sultans Of Swing solo tone.

too hot is just as bad as too cold, I would aim for around 70% normally.

[AiRdAd]

I had a Carr Amp whereby I could hook up a multimeter to a port and bias the amp. The manual said where to set the Bias to 66 millivolts. When I changed it colder to about 61 - I didn't like it. When I changed it hotter to about 71, there was a change, but really only a marginal change - not really a noticeable change. Maybe I could have done it even hotter? or was that about as far as you'd consider it safe to do?

[NippleWrestler]

It varies amp to amp.

Try this calculator:

https://robrobinette.com/Tube_Bias_Calculator.htm

You need the plate voltage which you measure from the tube pin(s), and the dissipation of the tubes. Then you can figure out a safe bias (in terms of tube life).

[griff]

Thank god I know a tech who can do this shit!

[NippleWrestler]

It takes 5 minutes to set bias, amp techs would have you believe it's some voodoo magic but you get the numbers, turn a pot and you're done. Nothing to it.

[chur]

It takes 5 minutes to set bias, amp techs would have you believe it's some voodoo magic but you get the numbers, turn a pot and you're done. Nothing to it.

You do need some special tools though yer.. probably not expensive, but needed regardless

[chur]

Thank god I know a tech who can do this shit!

I have my JCA22H in getting new power valves currently, one started arcing and randomly glowing bright red.. highly annoying and distracting mid solo with volume cutout.. oddly, other band members didn't say a thing, clearly they weren't listening to my awesomeness

[griff]

Thank god I know a tech who can do this shit!

I have my JCA22H in getting new power valves currently, one started arcing and randomly glowing bright red.. highly annoying and distracting mid solo with volume cutout.. oddly, other band members didn't say a thing, clearly they weren't listening to my awesomeness

hahaha
Biased too?