Tweet
Hey guys,
Today I was playing my 90's Tweed Bassman RI and as usual it was sounding great but just too freaking loud. I finally decided to do something about it so I can play the thing around the house without running in excess of 120dB!
First off I converted it to cathode bias, which is really easy to do. I pulled the transformer lead off the board and taped it off, and then grounded the junction of the 220K resistors. Then I put a 470 ohm, 10 watt resistor from pin 8 of the 6l6's to ground and bypassed it with 100uF @ 100 volts.
Then I put in a VVR circuit to scale the voltages in the whole amplifier. I had the parts laying around the shop so I put 'em to good use...
Drum roll, please...
It sounds absolutely terrific. It's still plenty loud if I run the voltage up, but I can now turn it down and maintain really decent tone at conversational levels. All in all, a great project.
I looked around and didn't see any reports of anyone else doing this so I thought I'd share my results with you all. If you're thinking about going cathode bias with a tweed bassman, I can say that it sounds great. A lot like my 5E3 deluxe but way bigger. Try it, you'll like it!
Dave
Today I was playing my 90's Tweed Bassman RI and as usual it was sounding great but just too freaking loud. I finally decided to do something about it so I can play the thing around the house without running in excess of 120dB!
First off I converted it to cathode bias, which is really easy to do. I pulled the transformer lead off the board and taped it off, and then grounded the junction of the 220K resistors. Then I put a 470 ohm, 10 watt resistor from pin 8 of the 6l6's to ground and bypassed it with 100uF @ 100 volts.
Then I put in a VVR circuit to scale the voltages in the whole amplifier. I had the parts laying around the shop so I put 'em to good use...
Drum roll, please...
It sounds absolutely terrific. It's still plenty loud if I run the voltage up, but I can now turn it down and maintain really decent tone at conversational levels. All in all, a great project.
I looked around and didn't see any reports of anyone else doing this so I thought I'd share my results with you all. If you're thinking about going cathode bias with a tweed bassman, I can say that it sounds great. A lot like my 5E3 deluxe but way bigger. Try it, you'll like it!
Dave