Welcome To the Hoffman Amplifiers Forum

September 08, 2025, 12:54:18 pm
guest image
Welcome, Guest. Please login or register.
-User Name
-Password



Hoffman Amps Forum image Author Topic: Power Transformer for Laub Engeering Model 26  (Read 2612 times)

0 Members and 1 Guest are viewing this topic.

Offline jamesedmunda

  • Level 1
  • *
  • Posts: 30
  • I love Tube amps
Hoffman Amps Forum image
Power Transformer for Laub Engeering Model 26
« on: August 22, 2020, 08:45:38 am »
I need a power transformer for a Laub Engeering model 26. Kind of a Magnatone 260 clone.
It looks like a Fender Hot Rod transformer would work.
 Doesa anyone see any problems, here's the specs.

Fender Original Hot Rod Deluxe Power Transformer. Equivalent to #036958.

Specifications Primary 120 VAC @ 60 Hz (Black - White) Secondary 1 (Red - Red) 495 VDC unloaded, 440 VDC @ 65.7 mA DC, 388 VDC @ 200 mA DC Secondary 2 (Brown - Brown) 53.6 VAC @ 1.58 A AC Secondary 3 (Green - Green) 6.6 VAC @ 3.75 A AC

Fender part number: 003-6958-000
 Mojotone has one with 4 amps on the Heater winding, would that be a better fit.

Fender Original Hot Rod Deluxe Power Transformer. Equivalent to #036958.


 Thanks again James

« Last Edit: August 22, 2020, 02:20:48 pm by jamesedmunda »

Offline vampwizzard

  • Level 3
  • ***
  • Posts: 501
  • Don't let the magic smoke out of the machines
    • Walbertedwards.com
Hoffman Amps Forum image
Re: Power Transformer for Laub Engeering Model 26
« Reply #1 on: August 22, 2020, 11:10:00 am »
You may be a little high on the B+ if you dont use the 48V winding otherwise it appears you have enough current available for the tubes.

Offline Latole

  • Level 4
  • *****
  • Posts: 2522
Hoffman Amps Forum image
Re: Power Transformer for Laub Engeering Model 26
« Reply #2 on: August 22, 2020, 11:26:24 am »
Did you check how much current tubes's heater need ?

Transformer specs are 6.6V at 3.75 amps

Offline vampwizzard

  • Level 3
  • ***
  • Posts: 501
  • Don't let the magic smoke out of the machines
    • Walbertedwards.com
Hoffman Amps Forum image
Re: Power Transformer for Laub Engeering Model 26
« Reply #3 on: August 22, 2020, 12:40:36 pm »
looks like those 6CG7's take .6A per tube. You're looking at ~4A of heater current. 

Offline DummyLoad

  • SMG
  • Level 5
  • *****
  • Posts: 5791
Hoffman Amps Forum image
Re: Power Transformer for Laub Engeering Model 26
« Reply #4 on: August 22, 2020, 02:55:58 pm »
another option.

https://www.edcorusa.com/xpwr021

--pete

Offline jamesedmunda

  • Level 1
  • *
  • Posts: 30
  • I love Tube amps
Hoffman Amps Forum image
Re: Power Transformer for Laub Engeering Model 26
« Reply #5 on: August 22, 2020, 03:06:33 pm »
Thanks for the reply Pete.
 Do you think the B++ is high enough the schematic shows 390 volts while the Edcor  transformer is only showing 290volts.
 Thanks James

Offline sluckey

  • Level 5
  • *******
  • Posts: 5075
    • Sluckey Amps
Hoffman Amps Forum image
Re: Power Transformer for Laub Engeering Model 26
« Reply #6 on: August 22, 2020, 03:44:27 pm »
Thanks for the reply Pete.
 Do you think the B++ is high enough the schematic shows 390 volts while the Edcor  transformer is only showing 290volts.
 Thanks James
290VAC will make about 410VDC unloaded. Probably be just about right with load. But, you've been looking at laydown type transformers. Can you use a standup type transformer?

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

Offline PRR

  • Level 5
  • *******
  • Posts: 17082
  • Maine USA
Hoffman Amps Forum image
Re: Power Transformer for Laub Engeering Model 26
« Reply #7 on: August 22, 2020, 05:03:19 pm »
> schematic shows 390 volts while the Edcor  transformer is only showing 290volts.

Schem is DC Volts, Edcor sells you AC Volts. Not the same. Counting on thumbs, 400V DC might be 282V AC. Or what DL said. More VAC if it was a tube rectifier, but it isn't.

A "5F6a Bassman" PT will work out to around 400VDC (with different rectifier connection!) but is probably over-kill (more current than you need).

Offline jamesedmunda

  • Level 1
  • *
  • Posts: 30
  • I love Tube amps
Hoffman Amps Forum image
Re: Power Transformer for Laub Engeering Model 26
« Reply #8 on: August 23, 2020, 04:39:18 pm »
Thanks Guys,
 I've ordered the Edcor.
James

 


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