Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Apprentice on January 31, 2019, 09:29:36 am

Title: Blues Junior Schematics
Post by: Apprentice on January 31, 2019, 09:29:36 am

Hi all can anyone let me know which of the Hoffman blues junior schematics is current. I have one with a bright cap and 130k resistor at the gain pot. and another without (which I have built). There are a couple of additional mods (resistor and cap removals) what is the reason for this. i.e. should I do the mods?

Title: Re: Blues Junior Schematics
Post by: sluckey on January 31, 2019, 10:19:41 am

All schematics are current. All the BJ schematics in the schematics library have a 100pF bright cap and a 130K on the volume pot. Can't say about the one you built. Hoffman's conversion has a 120K but not a bright cap.

Quote

There are a couple of additional mods (resistor and cap removals) what is the reason for this. i.e. should I do the mods?

Are you asking about the Hoffman conversion circuit? If you are doing the Hoffman conversion you should stick to his plan.

Title: Re: Blues Junior Schematics
Post by: Apprentice on January 31, 2019, 02:10:04 pm

I’m now a bit confused. I’ve attached the two schematics. I have built the one with 120k resistor but have now found other version. Are the changes purely tonal?

Title: Re: Blues Junior Schematics
Post by: sluckey on January 31, 2019, 03:24:01 pm

The old schematic you have that shows a bright cap also has a reverb send and return to be able to use the original BJ reverb circuit. Hoffman abandoned this idea.

This is the most current version...

     https://el34world.com/Hoffman/files/Hoffman_BluesJunior.pdf

Title: Re: Blues Junior Schematics
Post by: Apprentice on February 01, 2019, 03:50:53 am

Many thanks, I was beginning to question myself for a bit