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Fuse Holders-Cords-AC Items Handles-Amp Trim Parts Screws-Nuts-Washers Resistors
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Fuse Holders-Cords-AC Items Pots-Knobs Tube Sockets Tube Sockets
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Screws-Nuts-Washers Tools and Batteries Jacks-Plugs-Connectors Jacks-Plugs-Connectors
Tools and Batteries Tubes-Valves Jacks-Plugs-Connectors Wire-Cable-Heat shrink
Pots-Knobs Lamps-Diodes-Channel Switching Misc Hardware-Grommets-Feet-Ring terminals Switches
Fuse Holders-Cords-AC Items Transformers Switches Capacitors
Chassis-Boxes Misc Hardware-Grommets-Feet-Ring terminals Wire-Cable-Heat shrink Screws-Nuts-Washers
Tube Sockets Transformers Foot Pedals Tube Sockets
Wire-Cable-Heat shrink Circuit Board Building parts Guitar Strings Tube Sockets
Books Switches Jacks-Plugs-Connectors Tube Sockets
Transformers Fuse Holders-Cords-AC Items Transformers Resistors
Handles-Amp Trim Parts Lamps-Diodes-Channel Switching Transformers Capacitors
Tubes-Valves Circuit Board Building parts Jacks-Plugs-Connectors Tubes-Valves
Lamps-Diodes-Channel Switching Switches Pots-Knobs Fuse Holders-Cords-AC Items
Pots-Knobs Jacks-Plugs-Connectors Jacks-Plugs-Connectors Tools and Batteries
Handles-Amp Trim Parts Reverb tanks and Bags Foot Pedals Tube Sockets
Capacitors Resistors Lamps-Diodes-Channel Switching Jacks-Plugs-Connectors
Tools and Batteries Handles-Amp Trim Parts Screws-Nuts-Washers Bike Light Parts
Pots-Knobs Capacitors Pots-Knobs Fuse Holders-Cords-AC Items
Pots-Knobs Jacks-Plugs-Connectors Lamps-Diodes-Channel Switching Pots-Knobs
Screws-Nuts-Washers Resistors Lamps-Diodes-Channel Switching Capacitors
Circuit Board Building parts Pots-Knobs Switches Switches
Jacks-Plugs-Connectors
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Welcome to the EL34 World Tube Amp library of information.


Bookmark this page

This page is full of links that lead to every information page on my web site.
There is a ton of information below, take your time and read it all.
Many questions can be answered by studying the information below.

tube amp schematic tube amp layout diagram
Check out our huge library of Guitar Tube amp schematics,
effects schematics and many other types of schematics

The Tube Amp Schematics Library

Click on a link below to navigate around this page
This table is the index for all the info on this page.

Transformer wiring diagrams  *

Mods and Projects

Scratch Building amps

Hoffman board information and parts listings

Helpful info items

Technical and amp service information

Servicing Fender amps

Hoffman Amplifiers stuff

Sound Clips page - Tube amp sound clips and tunes of all types

Check out all my other hobbies and projects on this page

How to print the diagrams on my web site on your printer

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Windows printing tip
Any of the drawings or layout diagrams on my web site can be downloaded into your computer and printed on your printer.

Method 1: Put your mouse cursor on top of an image and then right click your mouse. Choose the "save picture as" option. Save the drawing on your Desktop or in a folder where you can find it. Open the drawing with your favorite drawing program. I use Paint Shop Pro to open and edit the drawings.

Method 2: Right click you mouse on top of an image, choose copy, then paste the image into your drawing program.

How to print the images larger:  In your drawing program, you can specify how you want your printer to print the drawing. Choose Landscape format and then Fit to page so the drawing fills out the entire width and length of the paper. I print the long drawings like the AB763 drawing on 8.5 x 14" legal size paper, but they still look good printed on 8.5" x 11" paper.



Links to technical and amp service information

Lots and lots of helpful people can be found on my Amp forum.
This is where you go to ask tube amp questions.
My Tube Amplifier and Guitar help forum

Amplifier service technicians listing

Tube amp Schematics and layout diagrams
Everything from Acoustic to Wurlitzer

PDF tube amp books that you can download
Right click on the links below and then choose "Save Target as"
Save the PDF files to your computer where you can find them and then read them via Adobe acrobat
Note that these are very large files.
Radiotron designers handbook 3rd edition - 16 mb
Radiotron designers handbook 4th edition - 25 mb

Plus all the links further down this page regarding amp servicing
Top of page



Hoffman Board information

What is a Hoffman board?
Hoffman boards are classic amp circuits that have been re-designed using my own turret lug layouts.
I didn't invent the circuits, I just came up with a slick way to organize the circuits on super neat turret lug boards.
What is a Hoffman board?

Note: I don't sell complete Hoffman boards.
I used to make them years ago and sell them.
See the board manufacturers listing for people that are authorized to make my board designs.


Hoffman board manufacturers
Hoffman Board manufacturing instructions
Hoffman board installation Instructions
Choosing a chassis for a Hoffman board
Scratch building an amp
Sound clips of some of the amps below

Note: The layout diagrams in this section below are my own designs.
Look at this page for layout diagram hookup info.
Common Hookup info for all Board layout diagrams *
Note: If there is an item on one of my layout diagrams this is confusing you,
it's probably because you did not look at the page above.


I now offer the bare Hoffman style boards as pre-drilled boards with un-finished edges that need sanding.
Go to my parts catalog to see these boards and for more info
Board building parts page

Pre Drilled tube amp board

I created some new layout diagrams for the pre-drilled boards I sell.
The new layouts are taken from my CAD program that I use to drill the board holes on my CNC machine.
The new layouts show the exact lug layout as it appears on the pre-drilled boards.
You still need to use the old layouts because they have way more wiring info than the new layouts.
The new layouts only show where the parts go from lug to lug.
The new layouts are large image files and may be way larger than your screen
Download the image files and print the new layouts on paper
Use them to assemble your projects.

The old layouts are labeled - Layout diagram #1
The new layouts are labeled - Layout diagram #2

New stuff to read here

Check out my new Parts List page.
Some of the items below have Parts list.
You can add all the parts to your shopping cart with one button click.
Parts List Page



Hoffman Princeton Reverb - layout diagram
Hoffman Princeton Reverb parts listing



Hoffman 5E3 Tweed Deluxe - layout diagram #1
Hoffman 5E3 Tweed Deluxe - layout diagram #2
Hoffman 5E3 Tweed Deluxe parts listing



Hoffman 6G15 stand alone reverb - layout diagram #1
Hoffman 6G15 stand alone reverb - layout diagram #2
Hoffman 6G15 stand alone Reverb unit parts listing



Hoffman AC30 - layout diagram #1
Hoffman AC30 - layout diagram #2
Hoffman AC30 parts listing



Hoffman AB763 - One Channel Layout diagram #1
Hoffman AB763 - One Channel Layout diagram #2


Hoffman AB763 - Two Channel Layout diagram #1
Hoffman AB763 - Two Channel Layout diagram #2

Hoffman AB763 - One and Two Channel Parts listing

You can see my AB763 project on this page

Hoffman AB763 Schematic
Thanks To Steve on the Hoffman Forum
The one channel board is the same, just eliminate the top channel on the schematic
Click on the image to see a larger image

One Channel AB763




Hoffman 5F6A Tweed Bassman - layout diagram #1
Hoffman 5F6A Tweed Bassman - layout diagram #2
Hoffman 5F6A Tweed Bassman parts listing
Bassman reissue filter cap hookup document



Hoffman Plexi50 - layout diagram #1
Hoffman Plexi50 - layout diagram # 2
Hoffman Plexi 50 parts listing
Marshall 50 watt power supply diagram


Hoffman Plexi100 - layout diagram #1
Hoffman Plexi100 - layout diagram # 2

The 100 watt has a unique power supply
Marshall 100 watt power supply diagram



There is more info on this board in the Mods and Projects section below

18 Watt Stout - layout diagram #1
18 Watt Stout - layout diagram #2
18 Watt Stout - schematic
18 Watt Stout - parts listing



There is more info on this board in the Mods and Projects section below

18 Watt Reverb Stout - layout Diagram #1
18 Watt Reverb Stout - layout Diagram #2
18 Watt Reverb Stout - Schematic
18 Watt Reverb Stout - Parts listing



ReVibe - Reverb/Vibrato stand alone unit
With the Tore-T ReVibe mod

Tore-T is a European gentleman that came up with a very cool mod that eliminates the hum that the original ReVibe had.
I modded my personal ReVibe with the Tore-T mod and it is dead quiet.
I would recommend building this version and not the original version.
Tore-T visits my amp forum on a regular basis.
ReVibe with Tore T mod - Layout Diagram #1
ReVibe with Tore T mod - Layout Diagram #2
ReVibe with Tore T mod - Schematic

Origins of the ReVibe

ReVibe - photo page
ReVibe -  parts listing

I built a ReVibe into a 3 high rack chassis
The Rack ReVibe project page
My Rack ReVibe Project on the forum


The original Re-Vibe had quite a bit of background hum.
I am not making a board for the original ReVibe
This section is here just for info purposes
Original Reverb/Vibrato Schematic
Original Hoffman style Reverb/Vibrato layout diagram - don't use this

Top of page



Mods and Projects

These mods and projects are not supported with any sort of tech support by me personally.
Some are projects that I have built for me personally or I built them to document a build process.
In some cases you need to have major fabrication skills to build these projects.
Please go to the Hoffman amp forum for technical questions.

Note: I don't recommend using relays to do switching unless you are an experienced builder.
Relays and switches add extra wire and can add hum and other problems unless your layout is perfect.
I prefer to hot wire the gain stages to keep wire lengths as short as possible.

Sound Clips of some of the projects below

I now offer the bare Hoffman boards as pre-drilled boards with un-finished edges that need sanding.
Go to my parts catalog - Board building parts page


Rack mount ReVibe


I like my ReVibe so much that I decided to build one in a 3 high Rack chassis.
I like Rack mounted gear because it takes up way less space,
the knobs all face out,
you don't have a bunch of gear sitting on the floor,
and it's easy to wire it all up using short George-L cables.

See the Hoffman Board Information section at the top of the forum for more ReVibe info.

The Rack ReVibe project page
My Rack ReVibe Project on the forum

Hoffman Revibe


What is an 18 Watt Stout?
If you take a stock Marshall 18 Watt circuit and add in another pre amp gain stage, you get a terrible monster amp that can go from clean to mean.
I added a second gain stage to the stock 18 watt circuit and call my version the 18 watt Stout.
I also came up with a way to wedge reverb into to the Stout, which is called the 18 watt Reverb Stout.


18 Watt Stout Project
The 18 watt Stout project Pictures

With switch to turn off gain stage
18 Watt Stout - layout diagram with voltages
18 Watt Stout - schematic

No switch - gain stage on full time
18 Watt Stout - layout diagram #1
18 Watt Stout - layout diagram #2
18 watt Stout bare board picture
18 Watt Stout - schematic

18 Watt Stout - parts listing - with or without switch or relay



18 Watt Reverb Stout

No switch - Gain stage on full time
18 watt Reverb Stout project#1 - Pictures
18 Watt Reverb Stout - layout Diagram #1
18 Watt Reverb Stout - layout Diagram #2
18 Watt Reverb Stout - voltages
18 Watt Reverb Stout - Schematic
18 Watt Reverb Stout - Parts listing

With relay to switch off Gain stage
The 18 watt Reverb Stout project#2 - Pictures
18 Watt Stout with Reverb - layout Diagram
18 Watt Stout with Reverb - Schematic
18 Watt Stout with Reverb - Parts listing

Top of page

More Mods and Projects

Tube pre amp in a pedal box
Notes: This is not a kit, it's a one of a kind personal project that I created from scratch.
It requires major fabrication skills.
It is a pre amp that I used for recording.
It is not a stomp box distortion pedal.
If you are thinking of building this, copy pedal #2 layout.
Pedal #2 was a much better layout design.

The tube pedal project
Tube pedal project parts listing
Tube pedal project schematic


All tube Stereo guitar pre amp project

Notes: This is not a kit, it's a one of a kind personal project that I created from scratch.
It requires major fabrication skills.
I built this stereo pre amp to use with my Stereo effects unit.
I now use it mainly for recording and it sounds great!

Stereo pre amp project

Stereo pre amp project- layout diagram
Stereo pre amp project - schematic

Hoffman pre amp

All tube Stereo guitar power amp project

Notes: This is not a kit, it's a one of a kind personal project that I created from scratch.
It requires major fabrication skills.
I built this stereo power amp to go along with the stereo pre amp above and my stereo effects unit.

Stereo power amp project

Stereo power amp project - schematic

Hoffman power amp

A Gibson GA-5 circuit built into a Schedule 40 PVC electrical box

The Schedule 40 GA-5 amp
Schedule 40 schematic
Original Gibson GA-5 schematic

Craig Barnett created a board layout and parts listing for the Schedule 40
Schedule 40 Circuit board layout diagram by Craig Barnett
Schedule 40 Parts listing by Craig Barnett


Hot switch Mod and relay switching info

Add a gain stage to some of my Hoffman style boards and other amps.
Hot Switch Mod


Relay switching info
Add a relay to the Hot switch mod and relay switching info


Compare to a regular Hoffman plexi layout diagram to see the before and after.
Plexi 50 with Hot Switch Mod schematic


Add reverb to the Western electric circuit.

Notes: The reverb mod works great.
I used this circuit on my 30 watt Hoffman combo amps.

Add Reverb to the western electric circuit.


How to assemble a Bias current checker

Hoffman Bias current checker
Most recent version using the new PC board

An Older version using my CNC'd PC board

A very old version that did not use a PC board


Wah Wah bypass switch mod
Add a true bypass foot switch to your wah pedal

Top of page


Helpful info items
Record you tube amp voltages here
Tube amp voltage recording page

 See voltage data that others have recorded
Tube amp voltage index page
The old valve data index page

LED current limiter resistor calculator

How to clamp down a EL84 9 pin tube socket
Cool amp tools
Fender bias circuit conversions
Fender cathode/fixed power tube conversions
Bassman reissue filter cap hookup document
Filter cap hookup solutions
How a bias circuit works

How to's
How to add a bias pot to a Princeton and other amps
Updated- How to use the turret lug tool
How to use the lead bender tools
How to solder wires and components to turret lugs
Add a true bypass foot switch to your wah pedal
How to wire Hi/Low input jacks - Cliff and Switchcraft types

Charts and Diagrams
Heater wiring diagram
Power transformer rectifier circuit diagrams
Rotary switch hookup photo
Amp Grounding diagram
Amplifier current flow
Capacitor code chart
Series speaker wiring
Parallel speaker wiring
4 Speaker Series/Parallel wiring diagram
Capacitors in series and parallel
Resistor code chart
Reverb Tank Chart
Fender transformer number conversion chart
Marshall rotary style voltage selector switch, power switch and transformer wiring diagram
Marshall toggle style power switch diagram and 5 pin to 4 pin conversion info
Marshall 50 watt power supply diagram
Marshall 100 watt power supply diagram

George-L cable review

Top of page


Servicing fender amps
  This is just a general Fender amp servicing guide. Many Fenders used the same circuit inside with just a few different parts in the same spot on the board. You don't need a special Deluxe Reverb service Guide to be able to Service a Super Reverb or a Pro reverb.
 STOP: Before doing any service work on an amplifier, you must make sure the amplifier is unplugged from the wall and the filter caps are drained. Filter caps can hold a charge that can give you a severe shock.
 The easiest way to drain your filter caps is to warm up the amp and then play the amp. Do not shut the amp off with the power switch or the standby switch. Just unplug the amp from the wall and keep strumming your guitar until the sound dies away.
  Once the sound dies down, the voltage in the filter caps will be below a level that can hurt you. There will still be a small voltage present in the caps but it is not enough to give you a nasty shock. Typically there is less than 20 volts is in the filter cap after draining it this way.

 Follow along with the instructions below by referring to the Super Reverb Layout diagram on this page
See this Windows diagram printing tip on how to print this diagram.
Updated
Inside the amp - caps, resistors, etc.
Filter caps
Jacks, pots and tube sockets
Power cord and fuses
The heater system
Biasing the amp
Oddball amp noises

Top of page


Transformer wiring diagrams

The links below lead to wiring diagrams for the transformers I currently sell, and older discontinued models
Note: I do not sell OEM Fender and Marshall transformers.
Most are copies of older style transformers.

Toroidal power transformer wiring diagram

Fender Style Transformer wiring Diagrams

Marshall Style Transformer wiring Diagrams

Discontinued Hoffman Transformers - wiring diagrams and info

Top of page


Hoffman Amplifiers stuff
This section has info on the Hoffman amplifiers that I used to build many years ago.
Notes: I do not build these amps, this section is just here for informational purposes.
There's also info on my personal stuff, photos' etc.

Photo pages

The original Hoffman 30 watt head
The original Hoffman 50 watt head
Hoffman 50 watt head chassis assembly
Later style 50 and 100 watt heads
Oddball Hoffman 30 watt combo
Amps that I made for Randall



Hoffman amp Diagrams

Stand alone reverb unit
Stand alone reverb unit face plate layout



Very early 30 watt heads with 2-EL84's and DC heaters
30 watt heads with 2-6V6's and DC heaters
30 watt heads with 2-6V6's and AC heaters
30 watt heads face plate layout



I called the early metal box heads the 2034 model

Early 50 watt heads with DC heaters
50 watt heads face plate layout
50 watt heads wiring diagram

I scanned the Metal template that I used to make the 2034 circuit boards
Here's an image of that metal template scan
50 Watt heads Metal Template scan image

Here's a .gif file you can use to drill the boards
50 Watt heads Template



These were the Marshall looking box heads I made after the early metal box heads
H50 and H100 later style pre amp layout diagram



30 watt combo's
30 watt combo front face plate layout
30 watt combo rear face plate layout



Diagrams of amps that I made for Randall

Randall 50/100 watt head pre amp layout
Randall 50/100 watt head power amp layout
Randall 50/100 watt head PC board pre amp layout
Randall 50/100 watt head PC board power amp layout


Personal stuff

My Main guitars and some amp photo's
Dickie Betts 1957 goldtop
Dickie Betts amp head stack
Dickie Betts photo's

Gerald Weber, Terry Oubre, Doug Hoffman, Bob Fieberts
Old Tube amp shop photo

Top of page

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Create your own custom Turret lug board

The Tube amp Library of information - Charts - Diagrams - How To's - Projects
Click the link above for Tube amp info, Schematics, Board building information, Projects, Mods, Transformer diagrams, Photo's, Sound clips.
There are hundreds of pages of Tube amp information on my library page.
Check out our huge library of Tube Amp Schematics here

Please visit my Tube Amplifier Forum
Here's the place you can go to ask tube amplifier questions.
You will find a large community of friendly amp builders at the link above.

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