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AB165 Bassman @ 499V B+

3/6/2000 7:31 PM
Ted	AB165 Bassman @ 499V B+ Hi I have a 66 Bassman which I have modded mostly back to AA864 (left the extra gain stage the same as in the AB165 though). I have noticed that it seems to distort fairly early @ 3-4 Volume setting. It seems to have quite high voltages compared to the schematics. I measure 499V on the 6L6 plates vs. the schematic 425V. The preamp tubes have correspondingly high plate voltages as well when compared with the schematic. This is while idling. It is a CSA tested PT (has a ink stamp CSA tested). I wonder if its a different PT than typical Bassmans? Can this higher voltage be causing some pre-amp distortion? Should I attempt to remedy the pre-amp plate volatages somehow? Thanks. Ted.

3/6/2000 7:31 PM

Ted

AB165 Bassman @ 499V B+

Hi I have a 66 Bassman which I have modded mostly back to AA864 (left the extra gain stage the same as in the AB165 though). I have noticed that it seems to distort fairly early @ 3-4 Volume setting.

It seems to have quite high voltages compared to the schematics. I measure 499V on the 6L6 plates vs. the schematic 425V. The preamp tubes have correspondingly high plate voltages as well when compared with the schematic. This is while idling.

It is a CSA tested PT (has a ink stamp CSA tested). I wonder if its a different PT than typical Bassmans?

Can this higher voltage be causing some pre-amp distortion? Should I attempt to remedy the pre-amp plate volatages somehow?

Thanks.
Ted.

Replies:

Corwin Ted: what is the voltage coming fro... -- 3/6/2000 8:26 PM