Welcome To the Hoffman Amplifiers Forum

September 06, 2025, 12:36:20 pm
guest image
Welcome, Guest. Please login or register.
-User Name
-Password



Hoffman Amps Forum image Author Topic: New amp D-HRM cathode biased  (Read 2526 times)

0 Members and 1 Guest are viewing this topic.

Offline tubenit

  • Global Moderator
  • Level 5
  • ******
  • Posts: 10274
  • Life is a daring adventure or nothing at all!
Hoffman Amps Forum image
New amp D-HRM cathode biased
« on: July 03, 2010, 08:15:06 am »
I wanted a low power D-type amp so I built this one. I think I may be done with the tweaking. Anyhow I am happy with it and DaGeezer and Sluckey gave me alot of help figuring out the foot switchable relay (since it was my first attempt at it). I did not use a traditional D-clone layout and the amp is still super quiet.

SCH schematic and layout are here:
http://www.el34world.com/Forum/index.php?topic=9498.0

With respect, Tubenit

Offline tubenit

  • Global Moderator
  • Level 5
  • ******
  • Posts: 10274
  • Life is a daring adventure or nothing at all!
Hoffman Amps Forum image
Re: New amp D-HRM cathode biased
« Reply #1 on: July 03, 2010, 08:18:30 am »
Chassis interior does not have very neat wiring but it is quiet.  I used a different HRM approach and instead of internal trim pots, I mounted them on top of the chassis for easy access. The front cab panel is attached with velcro which has worked on another cab with no problems for yrs & allows me easy access to change tubes.

Tubenit

Offline John

  • Level 3
  • ***
  • Posts: 1895
Hoffman Amps Forum image
Re: New amp D-HRM cathode biased
« Reply #2 on: July 03, 2010, 09:05:01 am »
Pretty cool.

Ya know, after I spent over a month re-capping, etc. my old amp, I thought I'd lose the fever to build one from scratch. Instead, I keep thinking of cabinet options for my first build.
Tapping into the inner tube.

Offline Geezer

  • Level 4
  • *****
  • Posts: 3680
  • Groov'n Tube'n KOOK (Keeper Of Odd Knowledge)
Hoffman Amps Forum image
Re: New amp D-HRM cathode biased
« Reply #3 on: July 03, 2010, 09:34:15 am »
WOW!!!!!!

All that FLAME!    It's on Fy-AH !!   :blob8:

Great work!
   Cunfuze-us say: "He who say "It can't be done" should stay out of way of him who doing it!"

 


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