Mojotone Custom 50 Guitar Tube Amp Kit


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SKU: 0755545
Weight: 30 lb
Sale Unit: Piece

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Please read our article 'Mojotone Amp Kit Building Primer' along with our amp kit disclaimer located in the Specs tab before buying this kit.

The design was a labor of love that started in a garage in New Malden, England. It quickly grew in local popularity, and made its way to the stage behind big names like the Who, Pink Floyd, Jethro Tull, the Moody Blues, and Manfred Mann. The legendary DR504 is synonymous with big, clean, and powerful.

Skilled amp builders, try your hand at recreating this sonic icon with our Mojotone Custom 50 amplifier kit.

The kit comes with everything necessary to build a working unit, including resistors from Ohmite and Vishay, Mojotone Dijon capacitors, Heyboer transformers, Belton tube sockets, and potentiometers by Alpha.

Also included is a full-color wiring diagram which provides a faithful road map of all the right angles and mil-spec techniques which were documented from studying two original examples from the early seventies.
  • Class Type: AB All Tube Amplifier
  • Output: ~50 Watts
  • Circuit: 1970-1972 DR504 Custom 50
  • Bias Type: Fixed Bias
  • Build Time: ~8 hours
  • Preamp Tubes: ECC83/12AX7 (3) & ECC81/12AT7 (1)
  • Output Tube(s): EL34 (2)
  • Rectifier Tube: None - Solid-state Rectified
  • Transformers: Power - Hiwatt 50W (MOJO786), Output - Hiwatt 50W (MOJO785)
  • Hardware:Mojotone Custom 50 Small Parts Kit, Custom 100 Chassis, Front & Rear Faceplates, Octal Base Clamps, 10' Removable Power Cord

Disclaimer: Some of the parts contained in this kit are subject to availability.

Mojotone reserves the right to change or substitute any and all of the parts contained in this amplifier kit without advertisement or notification to the buyer. Part substitutions made by Mojotone are guaranteed not to affect the integrity or operation of your amplifier kit. Time estimates listed are from start to finish. If you are new to tube amplifiers, additional time may need to be factored.


When purchasing a kit from Mojotone, you will receive the following documentation.

1. Schematic

2. Wiring Diagram / Layout

Our beginner level kits such as the tweed champ and tweed deluxe include a manual. If you purchase a kit from Mojotone and do not receive these documents, you can obtain copies by emailing or calling 800-927-6656. The Mojotone staff is available Monday through Friday from 8:30 a.m. to 5:00 p.m. EST unless otherwise closed.


Mojotone kits include the best quality parts that are available at the time of purchase. If a substitution is required, our team will use parts that are of equal quality to ensure the integrity of the kit build remains the same.


Building a fully functional amplifier kit is not an easy task. Before building a kit, one should have the ability to properly solder as well as read and understand a schematic and wiring diagram. While we do our very best to ensure all documentation is current, the included documentation is meant to serve as an overall guide to building the amplifier. Simply following the schematic and wiring diagram does not guarantee you will have a fully functional amplifier. In fact, post build troubleshooting is a common issue across all builds.


Our staff is available to assist with basic troubleshooting needs. There are plenty of online videos available that are helpful with most post build issues. Technical staff is available via email by sending a message to You may also call our sales team to discuss build problems, dial 800-927-6656 and press 1 for sales.


Building a tube amplifier takes time, dedication, resources and most importantly... Skills! The experience of building an amp can come with some frustration, the reward of completing the build is definitely well worth your time. Please review the wiring diagram, schematic and manual (if applicable) prior to making your purchase. Mojotone will not accept any returns on amplifier kits and/or parts that have been assembled, soldered or modified.

This amp kit also comes with the following documents. Please feel free to view and/or download them:

Custom 50 Schematic
Custom 50 Wiring Diagram

Other Videos Featuring This Product

Ratings & Reviews

5 reviews

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5/3/2024 11:08 pm

Great Hi-Watt sound, great beefy clean sound.

by Dave -

This was my third build from Mojotone. This is labeled as a difficult build. I think maybe its listed that way because the diagnosing of problems may be a little more challenging (unfamiliar?) compared to other amps. I didn't find it very hard to follow at all. Plenty of room to work on everything. Luckily all voltages were correct, and everything worked wonderfully on first start up. The thickness of the clean is just great. When you can play a signal note and it sounds full and then play a chord and all the notes actually come through cleanly. One of the filter caps was sent incorrectly, and the wiring diagram was missing, but Mojotone has been absolutely great to deal with and their customer service is top notch. Now I have a serious problem, and can't stop building these amp kits.

3/23/2024 5:03 pm

Beautiful kit, some notations.

by Sasha

Am currently rebuilding my old Peavey 5150 mk 1 head, but i wanted to try my hand at a hiwatt circuit. The Custom 50 is plenty for my needs & this will hands down be the first amp i build. As of writing this review, am in build process of the kit, but i wish to clarify a few things: Bias circuit will need some altering to keep the power tubes a little bit cooler than they would be with the stock "vintage" scheme. Triple check you have all your components, & when assembling verify all fit without hitch in or out on the chassis. My kit was missing a few parts, & my chassis' heat shield sat too close to the can caps. Mojotone's customer service swiftly resolved the missing parts, & sent my concern of the heatshield placement to have it corrected in future chassis (i made no request to swap my chassis as all else fits, & two holes to drill isn't a bother). Overall, great kit, superb build quality. Highly recommend. Take your time to build, the journey is enjoyable!