Welcome To the Hoffman Amplifiers Forum

September 08, 2025, 05:27:01 pm
guest image
Welcome, Guest. Please login or register.
-User Name
-Password



Hoffman Amps Forum image Author Topic: Blues Junior Schematics  (Read 8716 times)

0 Members and 1 Guest are viewing this topic.

Offline Apprentice

  • Level 1
  • *
  • Posts: 28
  • I love Tube amps
Hoffman Amps Forum image
Blues Junior Schematics
« 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?

Offline sluckey

  • Level 5
  • *******
  • Posts: 5075
    • Sluckey Amps
Hoffman Amps Forum image
Re: Blues Junior Schematics
« Reply #1 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.


A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline Apprentice

  • Level 1
  • *
  • Posts: 28
  • I love Tube amps
Hoffman Amps Forum image
Re: Blues Junior Schematics
« Reply #2 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?

Offline sluckey

  • Level 5
  • *******
  • Posts: 5075
    • Sluckey Amps
Hoffman Amps Forum image
Re: Blues Junior Schematics
« Reply #3 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
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline Apprentice

  • Level 1
  • *
  • Posts: 28
  • I love Tube amps
Hoffman Amps Forum image
Re: Blues Junior Schematics
« Reply #4 on: February 01, 2019, 03:50:53 am »
Many thanks, I was beginning to question myself for a bit

 


Choose a link from the
Hoffman Amplifiers parts catalog
Mobile Device
Catalog Link
Yard Sale
Discontinued
Misc. Hardware
What's New Board Building
 Parts
Amp trim
Handles
Lamps
Diodes
Hoffman Turret
 Boards
Channel
Switching
Resistors Fender Eyelet
 Boards
Screws/Nuts
Washers
Jacks/Plugs
Connectors
Misc Eyelet
Boards
Tools
Capacitors Custom Boards
Tubes
Valves
Pots
Knobs
Fuses/Cords Chassis
Tube
Sockets
Switches Wire
Cable


Handy Links
Tube Amp Library
Tube Amp
Schematics library
Design a custom Eyelet or
Turret Board
DIY Layout Creator
File analyzer program
DIY Layout Creator
File library
Transformer Wiring
Diagrams
Hoffmanamps
Facebook page
Hoffman Amplifiers
Discount Program


password