Welcome To the Hoffman Amplifiers Forum

September 06, 2025, 01:27:21 pm
guest image
Welcome, Guest. Please login or register.
-User Name
-Password



Hoffman Amps Forum image Author Topic: TOS Voltages  (Read 2674 times)

0 Members and 1 Guest are viewing this topic.

Offline sdp1234

  • Level 1
  • *
  • Posts: 86
  • I love tube amps
Hoffman Amps Forum image
TOS Voltages
« on: October 25, 2010, 08:11:32 am »
I'm planning a TOS build and currently plan to use a salvaged PT from a Hammond Organ.  The voltages are listed as 285-0-285.  It had a 5u4 rectifier.  Based on the tube compliment I think it will be in the 350 DC range and should be able to provide over 200 ma if needed.  Heater current should be good for any tube complement.    I'm not sure what output tube I want to use but I'd like to try 6v6's, el34's 5881's and 6l6's.  Is the voltage high enough for the TOS?  Are there any of these output tubes I can't try?  For flexibility I plan to try the webber 45 watt Marshall output transformer 3400(6800) : 2(4), 4(8), 8(16), 16(32).

Offline tubenit

  • Global Moderator
  • Level 5
  • ******
  • Posts: 10274
  • Life is a daring adventure or nothing at all!
Hoffman Amps Forum image
Re: TOS Voltages
« Reply #1 on: October 25, 2010, 08:17:30 am »
I am currently using a 275-0-275  150 ma PT with GZ34 rectifier and 5881 tubes.  It works fine for me. I also use 6V6's sometimes in it (but not as often). I think I have around 360v on the 5881 plates?

On top of that, I use a VVR on the power amp and LTPI which further lowers the voltages and typically have the VVR set at about "5" more or less.

You could consider using a SS rectifier which would give you around 265 v X 1.4 = 371v.

With respect, Tubenit


Offline drumslinger2000

  • Level 2
  • **
  • Posts: 106
Hoffman Amps Forum image
Re: TOS Voltages
« Reply #2 on: October 25, 2010, 09:16:09 pm »
Is vibrolux iron ok for a TOS build?  I have an extra set lying around.  what seems to be the ideal iron to use?

Offline sdp1234

  • Level 1
  • *
  • Posts: 86
  • I love tube amps
Hoffman Amps Forum image
Re: TOS Voltages
« Reply #3 on: February 09, 2011, 12:54:02 pm »
I have the choice between two PT's that I have on hand. 

1. 285-0-285 - 200+ ma
2. this transformer has 2 HV taps one is 265-0-265 and the other is 320-0-320.  at 150 ma

Due to size and weight Id rather use the second PT.  Would this be enough for most tube choices or would i be better off having the extra current of the larger PT? 

 


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