Bassman AA864 / AA165 Filter Caps

[Deric]

I have what appears to be an AA165 that someone attempted to convert to an AA864 on my bench. Most values had been changed to AA864 including the removal of the 8uf filter cap for the input stages.

Had some hum issues that I was able to clean up by fixing grounds and and removing a half-assed DC heater mod. Re-wired the Bass channel to AA165 spec since the pot values had not been changed, replaced the remaining filter caps, bypass caps, bias cap, out of spec resistors, etc...

Amp sounds great and is hum free. V1 plate voltage is ~285vdc. Is there any good reason not to replace the missing filter cap and 27k dropping resistor?

Thanks

[Stevem]

No reason not to, but there will be a effect of less drive voltage out of that V1 stage since you will then have about 220 to 240 volts on that incoming end of that plate load resistor.

This will also mean some level of lesser high end out of that gain stage ( browner sound if you will) and that stage will also clip sonner and your down stream stages a bit later due the lesser drive signal.

Remember it was a Bass amp if the owner is playing guitar thru it then set it up like a superreverb unless he has very hot pickups or a stomp box he goes thru.

[Deric]

The owner has played it for a bit as it is now and digs it. Will likely leave it as is but will let him know and see if he's interested in the changes.

Thanks for the input!