Welcome To the Hoffman Amplifiers Forum

September 06, 2025, 01:20:41 pm
guest image
Welcome, Guest. Please login or register.
-User Name
-Password



Hoffman Amps Forum image Author Topic: '70's Fender Twin Reverb Trilogy of Schematics  (Read 22949 times)

0 Members and 1 Guest are viewing this topic.

Offline 2deaf

  • Level 3
  • ***
  • Posts: 1667
  • Now too deaf for 100 watts
Hoffman Amps Forum image
'70's Fender Twin Reverb Trilogy of Schematics
« on: April 29, 2019, 11:38:51 pm »
I was never a fan of the '70's Fender drawing style, so I drew my own. 

Offline sluckey

  • Level 5
  • *******
  • Posts: 5075
    • Sluckey Amps
Hoffman Amps Forum image
Re: '70's Fender Twin Reverb Trilogy of Schematics
« Reply #1 on: April 30, 2019, 06:40:40 am »
Very nice! Easy on the eyes. I put all 3 in a single pdf and tucked it away. Thanks.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline BrownIsound

  • Level 1
  • *
  • Posts: 24
  • I love Tube amps
Hoffman Amps Forum image
Re: '70's Fender Twin Reverb Trilogy of Schematics
« Reply #2 on: November 16, 2023, 07:43:37 am »
Hi, I see an error in your schematics (unless you are correcting an error on the original fender schematics?), it looks like there is a feedback feed from the output of the LTP V6A, a 220k ohm resistor connected after the 0.1uf coupling cap on the Fender schematics, yours is connected to the 68k top 6L6s input grid load resistor and the bias balance pot.

This would lower the feedback, and maybe this was an intentional effect for your schematics?

But otherwise very nice schematics!  I have a late 1971 quad reverb and a Super Six, all the date codes on the transformers in both other than the chokes match exactly.
« Last Edit: November 16, 2023, 07:49:28 am by BrownIsound »

Offline sluckey

  • Level 5
  • *******
  • Posts: 5075
    • Sluckey Amps
Hoffman Amps Forum image
Re: '70's Fender Twin Reverb Trilogy of Schematics
« Reply #3 on: November 16, 2023, 08:56:57 am »
Hi, I see an error in your schematics
So it seems.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline Lambertini

  • Level 2
  • **
  • Posts: 101
  • Learning tube amps
Hoffman Amps Forum image
Re: '70's Fender Twin Reverb Trilogy of Schematics
« Reply #4 on: December 10, 2023, 09:10:46 am »
@2deaf:
Thank you for these easy-to-read schematics.

@BrownIsound:
Thank you for noticing the 68k resistor placement error.
I've updated the 2 schematics I'm interrested in. Can you please check if the fix is ok?


« Last Edit: December 10, 2023, 09:16:09 am by Lambertini »

Offline BrownIsound

  • Level 1
  • *
  • Posts: 24
  • I love Tube amps
Hoffman Amps Forum image
Re: '70's Fender Twin Reverb Trilogy of Schematics
« Reply #5 on: December 10, 2023, 06:01:25 pm »
Looks good, I just checked the one w/o MV.

Offline Lambertini

  • Level 2
  • **
  • Posts: 101
  • Learning tube amps
Hoffman Amps Forum image
Re: '70's Fender Twin Reverb Trilogy of Schematics
« Reply #6 on: December 10, 2023, 06:30:53 pm »
Did the same update on both. Thank you!

 


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