how do you bias your amps?

[LSD-Studio]

usually you're aiming for 50-70% dissipation...I'm usually at something like 65%...what about you?

EDIT: title might be confusing...I don't wanna know HOW you bias them (the technical way), but how high you're setting the idle current

 

[GuitarHack]

On the Rev with the JJ's I set it at 70%.

30W/526V x 0.7 = 39.9mA (from memory 526V is what the plate voltage was).

https://taweber.powweb.com/biasrite/br_page.htm

I use the BR-4 Octal. You can easily switch between tubes and read either the Plate Voltage or Bias current with the flick of a switch.

 

[Torniojaws]

Most tube manufacturers have their own recommendations for their tubes, depending on the tube type (6L6, 5881, EL-34, etc).

That said, I use 70 % for my 6L6s. Haven't biased my Marshall (EL-34) yet, since the previous owner changed new tubes in and biased it before selling the amp to me 10 months ago.

 

[Metaltastic]

Yeah, I rock my JSX at around 38 mA

 

[abyssofdreams]

stupid question: my 5150 has a fixed non-adjustible bias. Do I need to adjust it somehow?

 

[Metaltastic]

Nope, you're unable to unless you get the bias mod.

 

[Meisterjäger]

I just scored a 6505 with a Bias Mod. Guy says he's running it at about 35mA, and it started life at about 14mA.

 

[abyssofdreams]

Nope, you're unable to unless you get the bias mod.

do I need it?

 

[Torniojaws]

do I need it?

You don't need it, but it can help you get a better (subjective) tone.

 

[53Crëw]

....Depends on the amp, and the brand of tubes.... but I usually run around 60 - 65% of max plate dissipation. Although, I'm liking my 5150 set cold lately... closer to stock... Currently it's at 30%. lol

 

[Glenn Fricker]

Cranked mine way back as well. Had it running at about 38mA till I changed cabinets... now i just set it by ear.