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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. |
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| Check out our huge library of Guitar Tube amp schematics, effects schematics and many other types of schematics The Tube Amp Schematics Library |
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| 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 |
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| 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  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 New 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 New 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  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 |
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| 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  |
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 |
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| 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  |
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  |
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  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 |
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| 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. |
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 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 |
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