M90 Tubes/Biasing

[mcdyas]

I got an M90 recently and I checked the bias on the Gold Lion KT88's. It reads under 30 mV per tube. I thought that KT88's typically want to be bias around 37- any comments on that?

Also, the manual says EL34's can be put in the amp with a re-bias. I assume this does not mean any cap/resistor change, right? Where is my bias pot? I pulled the chassis and didn't see anything that looked obvious as a bias pot.

Any help or advice would definitely be appreciated.

Thanks-

Mike

 

[61reissue]

http://www.guitarstudio.tv/Elmwood/elmw ... ontrol.htm

Should be the same location as the 90.

 

[ElmwoodAmps]

Hello Mike

Reading 30mA per tube is a bit to low for the KT 88's.
We set the bias to approximately 45-50 mA per tube( Shuguangs) as stock.
The bias trimmer is located at the same place as in the M60.
Instead of sitting under a pcb with a relay on it, as in the M60, the pcb above the trimmer carries a capacitor in the M90.
Send an e-mail to info@elmwood.se and I will return it with a "how to" bias guide.

Regards

Jan
Elmwood Amps