6L6 bias question

[rbailey1010]

Hey there guys....

Whats everyone biasing their 6L6GCs at? I want to bias them a little on the hot side but want to know what the common bias is around here is....

BTW....I am running Ruby 6L6GCMSTRs

Thanks again

 

[Zander]

35.

I'd wager Julia will tell you that's too high, but given what I've read and seen, that's a very common, if not "the" millivoltage to set to.

 

[JKD]

32

 

[Mattfig]

I can't crank mine beyond 32....Is that normal??

 

[nomad100]

no cooler than 35 for me

 

[Julia]

Maximum Plate Dissipation (in Watts) -- when in doubt check the tube manufacturer's web site for technical information (this would be New Sensor, SED, JJ, Shuguang, etc.)

5881, EL34, 6CA7, E34L, 6L6, KT66, KT77 = 25W

JJ 6L6GC = 30W

6550 = 35W

The transformer on the RM100 accd to Randall Tech Support is rated at 530 V to the plate for calculation purposes. Calculate your bias between 50% and 70%. Make sure you measure your house line voltage first because if it is low, you will bias too hot. Last time I set my bias when my line voltage was at 122V. During the day in the summer time it can drop to 115V.

 

[I am Legion]

34

 

[robespierre]

I just recently bought a RM50LB combo, brand new.

Should I be worried about checking the bias on the tubes (they're E34Ls)?

Or, since it's new, should I assume everything is fine?

 

[Mattfig]

GOtta check it....

 

[nomad100]

mine amp had 6L6's set at 42ma when i got it.

 

[kc2eeb]

Something to remember when setting bias;
When you set the bias in a Randall or any other amp that uses
the "voltage drop across a 1 OHM resistor between the Cathode and ground" method, you are also measuring the current added by the screen grid resistor. So, the actual bias is really slightly LOWER than what you
are measuring. So, 35ma(mv) is probably 33-34ma actual quiescent (idle) current.