Welcome To the Hoffman Amplifiers Forum

September 06, 2025, 12:50:58 pm
guest image
Welcome, Guest. Please login or register.
-User Name
-Password



Hoffman Amps Forum image Author Topic: PT wiring question / confirmation  (Read 1636 times)

0 Members and 1 Guest are viewing this topic.

Offline Bieworm

  • Level 3
  • ***
  • Posts: 705
  • I like it loud!
Hoffman Amps Forum image
PT wiring question / confirmation
« on: June 13, 2022, 02:36:03 am »
Hi guys!

There is something in need to get confirmed. Am I correct to assume that when I use the secondary HT winding like in the drawing that I should end up with a 'kind of' half power switching? I mean, I could use the winding like that, no?

Thanks in advance...
"This should be played at high volume.. preferably in a residential area"

Offline sluckey

  • Level 5
  • *******
  • Posts: 5075
    • Sluckey Amps
Hoffman Amps Forum image
Re: PT wiring question / confirmation
« Reply #1 on: June 13, 2022, 05:29:18 am »
The idea is sound but your voltages are wrong. You really have 0v-300v-600v which will give you about 848v or 424v into a cap input filter.

The Twin amp does something similar but with lower voltages. Notice that only the output tubes plates and screens are changed while the rest of the amp uses the "high power" voltages. Oh yeah, you must also switch the bias voltage.

IMO The Twin method is more realistic than your idea.
« Last Edit: June 13, 2022, 05:33:45 am by sluckey »
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline Bieworm

  • Level 3
  • ***
  • Posts: 705
  • I like it loud!
Hoffman Amps Forum image
Re: PT wiring question / confirmation
« Reply #2 on: June 13, 2022, 06:13:17 am »
Thanks Steve!

I'd be better off with this one then?

https://www.tube-town.net/ttstore/toroidal-185va-power.html
"This should be played at high volume.. preferably in a residential area"

Offline sluckey

  • Level 5
  • *******
  • Posts: 5075
    • Sluckey Amps
Hoffman Amps Forum image
Re: PT wiring question / confirmation
« Reply #3 on: June 13, 2022, 06:39:14 am »
That gives more practical voltages. If you plan to implement this idea into a real amp then I urge you to study the twin method and copy that instead of simply switching the AC voltage per your drawing.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO 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