Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: isaac_teller on May 25, 2021, 12:28:44 pm

Title: Musicmaster amp with fixed bias
Post by: isaac_teller on May 25, 2021, 12:28:44 pm
Hello. I have a Fender Musicmaster amp with 6V6 tubes. It's about 10 watts. I would like to give it a bit more punch without investing an excess amount of money(For example putting in larger power and output transformers that can handle 6L6 tubes). Is it possible to remove the 220 ohm cathode resistor, ground the cathodes, add a bias circuit with the bias voltage going to the center tap of the interstage transformer? Thank you.
http://www.prowessamplifiers.com/schematics/fender/musicmaster_bass_schem.pdf
Title: Re: Musicmaster amp with fixed bias
Post by: sluckey on May 25, 2021, 01:46:55 pm
Is it possible to remove the 220 ohm cathode resistor, ground the cathodes, add a bias circuit with the bias voltage going to the center tap of the interstage transformer?
Sounds feasible. I would convert to fixed bias with the 6V6s first since there's little money involved. Get that working and evaluate. Only then would I start throwing money at it.   :icon_biggrin:
Title: Re: Musicmaster amp with fixed bias
Post by: PRR on May 25, 2021, 01:58:11 pm
> give it a bit more punch without investing an excess amount of money

If Fender coulda, they woulda. But usually you get what you pay for (or less).

It's about 12% more power, 0.5dB. I don't think you could tell the difference in a dark club.
Title: Re: Musicmaster amp with fixed bias
Post by: isaac_teller on May 25, 2021, 02:43:01 pm
Thank you.