Bluesmaster PAB?

[Mark]

The PAB enables a huge amount of boost from the preamp as we all know.

I have seen this sort of thing before in the Mark 1 Mesa Boogies. Though it was purely a switch to open circuit the end of the mid pot from a ground path.

The Dumble PAB boost is similar with the exception of the 22M resistor between the wiper of the mid pot to the bottom of the bass pot. I would be surprised if this actually does anything.

Has anyone looked into the purpose of part of the PAB?

Look forward to your replies.

[bluesfendermanblues]

The Dumble PAB boost is similar with the exception of the 22M resistor between the wiper of the mid pot to the bottom of the bass pot. I would be surprised if this actually does anything.

No, the 22M doesn't do anything for the sound, but it enables noiseless switching of the PAB.


BTW the 22M option is known as the 'mega boost' - I use 68k- 82k on my Bluesmaster.

[Mark]

Thanks for the quick reply.

I had been using two 4.7Meg resistors in series and decided to go to two 10Meg resistors in series, I suspect there will be no difference in output between 20M and 8.4M.

BFMB, the thing that has me wondering is I only had the 8.7M resistor for boost. The mid/bass pot was hard wired as the 22M resistor between the wiper and the top of the mid pot (bottom of bass pot) seemed pointless to me.

We know HAD isn't silly, so what prompted him to include this part of the circuit.

I'll accept that he knew one day someone would reverse engineer his amps (nice words for copy, remembering imitation is the sincerest form of flattery) and this little circuit would do their heads in for a while.

[angelodp]

On my Dlite I do not have the 22m resistors and do not have any issue with a pop. I have read that they are not significant sonically, but also read that they create the mega-boost? So without them its ?? Semi-mega-boost?

Please clarify.