Mesa Heartbreaker bias pot

[Zouto]

Hi, for better biasing I want to put a bias pot into a Mesa Heartbreaker.Which one of the bias resistors is best to be replaced by the pot?Schematics
http://www.freeinfosociety.com/elect...iew.php?id=508
Thanks,
Zouto

[Zouto]

Any....

Any suggestions much appreciated.....
Zouto

[Pedro Vecino]

Using 6L6, the 10K resistor paralleled to 220uF in bias circuit. If you need to raise the work regime (the usual thing with Mesa) it?s better to use resistors in parallel with it.
With 100K paralleled: 9K
With 47K, 8,2K
With 27K, 7,3K...

Later probably you will need to readjust the 33k resistor (tube) to compensate the new work regime (bias) that produces the voltage drop of tube rectifiers.

Finally, If you are going to use them, the general adjust for EL34 because usually in Mesa there is higher that in 6L6 (for an "medium grade") and if you have raised this last, the most possible thing is that it remains higher still.
Regards

[Zouto]

Thanks Pedro,
wouldn't it be better to take a 10K pot (one lug connected to 5K or 2K2 in series to gnd) instead of using parallel resistors? The amp is played with 6L6s and GZ34 only, so biasing will be easier.
Zouto