– Replace the 0.022u F coupling caps in front of the 6L6 to 0.1u F.
ranchidating 2016 jelsoft enterprises ltd - Dating fender transformer code
(click on image to view full size) 2) Negative feedback loop The negative feedback loop can easily be tweaked to alter the treble cut and distortion in your amp.
The purpose of the NBF loop is to clean up the tone and cancel out the mid/higher frequencies and upper harmonics (distortion) at the entry point of the phase inverter which is placed in front of the power tubes.
– Remove the 220k feedback resistors from each of the plates on the two 6L6 tubes.
You will get more breakup and distortion and more volume at a given volume knob setting.
The next time you get into a Fender Bassman discussion you should narrow down exact which era, model and circuit you’re discussing. The tube charts are not very useful for determining the circuit model.
A lof of blackface Bassman amps with AA864 tube charts are actually AA165’s, and a lot of AA165 charts are glued into AB165 amps.
We’ll come back to this later in the “blackface chapter” below where we’ll demystify some of the hypes with the popular AA864.
The AA165 is very rare and its circuit and tone is quite similar to the AA864.
The bassman was a combo amp in the tweed era with the 1×15″ and 4×10″ speaker configurations.