I have a Traynor YSR-1 that is need of new EL34 tubes. How do I go about checking the bias after I get the new tubes?. Its a fixed bias, no adjustment pots, and it has a bias vary tremolo which is something new to me.
Turn the trem off, and measure tube current as you would for anything else. The tube currents at the plate voltage yields dissipation, which is within limits or not. Or do you just not know about measuring bias current in general?
If the trem works, unless the thing sounds real weird, I'd assume it was OK.
If the trem works, unless the thing sounds real weird, I'd assume it was OK.
Schematic
http://www.lynx.bc.ca/~jc/moddedYSR1.gif
Set tremolo to 0 or remove V7 and measure plate current and plate voltage , so you get actual plate dissipation...
http://www.lynx.bc.ca/~jc/moddedYSR1.gif
Set tremolo to 0 or remove V7 and measure plate current and plate voltage , so you get actual plate dissipation...
I understand how to take the measurements, I am unclear as to how to make the actual adjustment. Fixed bias is new to me. I would think changing R49 would do it but I haven't the experience to be sure.
SInce the amp has no adjustment, we would take the readings to determine that the tube bias fell within safe limits, and that is it. The way to alter it would be to make R48 variable. But the amp itself won't care if the bias is set to some super precise readings. All the amp wants is tubes that don;t red plate or be running so cold the crossover distortion is huge.
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