Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: blues man on April 03, 2011, 08:10:56 pm

Title: Bassman Ten rebuild
Post by: blues man on April 03, 2011, 08:10:56 pm

I just finished the build. Its a plexi for the lead channel and a 6g6 bassman for the rythm. I have posted the sch. I have one issue so far. When you dime the vol on the lead channel you can only get the master up to about 3/4. Above that it sounds like it's becoming unstable. Feed back as well as some possible parasitic oscillation. Any tips on taming it down a little. I thought about maybe changing out the 1.5k res on the power tube grids to a higher value like 5.6. would that help?

Title: Re: Bassman Ten rebuild
Post by: VMS on April 04, 2011, 09:23:18 am

What happens if you remove V3 tube?

Also, how close are the volume pot wires to the wires of tonestack and master pot?

Title: Re: Bassman Ten rebuild
Post by: blues man on April 04, 2011, 07:06:41 pm

Thanks for the tip VMS. The master vol wire was routed right by the vol wire and pot. I rerouted the wire and cut off about 4" of wire. I did use shielded wire originally but layout does matter. It definitely got rid of the parasitic. I didn't have time to thoroughly check it out but will tomorrow. I'm trying to rush the build to much and get it done. I just signed up to take the masters electrical exam. The amp building is going on the back burner for the next month.