Hoffman Amplifiers Tube Amp Library
Welcome to the EL34 World Tube Amp library of information.Bookmark this pageThis 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. Click on the Bookmark Links below to navigate around this page |
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Hoffman Turret boards Note that Hoffman boards are not assembled by looking at my builds. I do test builds first and change the designs based on those builds. You assemble Hoffman boards using the documents listed under each board Go to the Hoffman Turret board links below Read every document listed for that board Hoffman Turret board information Hoffman 5E1-5F1 Tweed Champ Hoffman 5F2A Princeton Hoffman 5E3 Tweed Deluxe Hoffman 5F6A Bassman Hoffman 6G15 Reverb Unit Hoffman AC30 Hoffman AB763 One Channel Hoffman AB763 Two Channel Hoffman AB763 Two Channel - Twin Reverb Hoffman AB763 Two Channel - Short Board Hoffman Blues Junior Conversion Hoffman Plexi 6V6 Hoffman Plexi 50 Hoffman Pro Junior Conversion Hoffman Princeton Reverb Hoffman ReVibe Hoffman Stout Hoffman Stout TMB Hoffman Stout Reverb Other Boards I make |
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Mods and Projects 1 Note that Hoffman boards are not assembled by looking at my builds. I do test builds first and change the designs based on those builds. You assemble Hoffman boards using the documents listed under each board Hoffman Plexi 6V6 Build Hoffman Blues Junior Conversion Build Hoffman Princeton Reverb Build 5F1 Champ Board Build Hoffman AB763 One Channel Build Rack Mount ReVibe Project Hoffman 18 Watt Stout TMB Project Hoffman 18 Watt Stout Project Hoffman 18 Watt Stout Reverb Project Mods and Projects 2 Tube Pre Amp in a Pedal Box project Tube Stereo Guitar Pre Amp Project Tube Stereo Guitar Power Amp project Schedule 40 Project Mods and Projects 3 Hot Switch Mod and Relay switching Info Add Reverb to the Western Electric Circuit How To Assemble a Hoffman Bias Checker Wah Wah Bypass Mod |
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DIYLC - Do It Yourself Layout Creator Create layouts and schematics with this free program Go here for more information about DIYLC Download .diy files and templates DIY file library Have custom boards made using DIYLC DIY file analyzer program Hoffman Amplifiers Web Store Check out the huge library of Guitar Tube amp schematics, effects schematics and many other types of schematics The Tube Amp Schematics Library Transformer wiring diagrams Helpful information links Servicing Fender Amplifiers Info: Scratch Building amps Design your own custom Turret Board or Eyelet board Technical and amp service information 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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| 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 |
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| Mods and Projects 2 |
| These are some of my personal projects They were one off type scratch builds I do not make boards or kits for the projects below |
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 - Page 1 The tube pedal project - Page 2 The tube pedal project - Page 3 The tube pedal project - page 4 Tube pedal project parts listing Tube pedal project schematic Top of page |
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  Top of page |
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 
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Rack mount ReVibe Project I liked my first 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 
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Schedule 40 Project 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 |
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| Mods and Projects 3 |
| Misc. Mods and Info |
Hot switch Mod and relay switching info Updated on 05/12/2018 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. 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 Top of page |
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. This is a post on my amp forum This is not one of my mods Adding one tube reverb Top of page |
How to assemble a Bias current checker  Most recent Bias Checker version using the new PC board An Older version using my CNC PC board A very old version that did not use a PC board Top of page |
Wah Wah bypass switch mod Add a true bypass foot switch to your wah pedal |
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Servicing Fender Amplifiers  |
This is my Fender amp servicing guide. I developed this service guide after many years of servicing Fender Vintage amplifiers. 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 service guide for each amp to be able to service a Deluxe Reverb, Super Reverb, Pro reverb or any of the vintage fender amps. 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 Fender Layout diagram on this page. |
| Servicing Fender amps 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 |
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| Transformer wiring diagrams |
The links below lead to wiring diagrams for the transformers I have sold Older discontinued models are here also Toroidal power transformer wiring diagram Fender Style Transformer wiring Diagrams Marshall Style Transformer wiring Diagrams Discontinued Hoffman Transformers - wiring diagrams and info |
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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 and 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. This topic on my amp forum describes how to print 8.5 x 22 inch extra large drawings How to print really large layout diagrams |
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