Traynor bass amp running hot/bias resistor

[Diverted]

Hi,

How would I increase the negative bias in this Traynor bass amp? It's non-adjustable fixed bias and currently the 6AC7s are running at about 80 percent. Would I want to reduce the 33K (R32) just prior to the bias diode, or would I be better off adjusting the 47K (R31) after the diode? Thanks.

[sluckey]

Put a 50K pot in series with that 47K.

[Diverted]

Can't do a pot on this one, he doesn't want it. So instead, I guess just try upping the value of that resistor ... maybe 51K, 56K, etc.? Thanks for the tip.

[sluckey]

Tell him that he may have to go through this every time he changes tubes unless he submits to the pot.   

Changing the value of a resistor is just as much a mod as adding a trim pot.   

[2deaf]

Can't do a pot on this one, he doesn't want it. So instead, I guess just try upping the value of that resistor ... maybe 51K, 56K, etc.? Thanks for the tip.

My money is on 51K.

36K in series with a 25K pot if you want to go that route.