British Style 50W 800 Amplifier Kit

3 Reviews
$637.38 to $895.00
SKU: G1800969

Check our Resources page for current build times.

On Back Order

Kit Build Difficulty:

This kit has a lead time.  Check here for more information.

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

This kit produces similar tones to a 81-90 Marshall® JCM800 2204.

  • Class Type:AB All Tube Amplifier
  • Output:~50 Watts
  • Circuit:2204
  • Bias Type:Fixed Bias with an adjustable potentiometer
  • Build Time:~7 hours
  • Preamp Tubes:JJ ECC83/12AX7 (3)
  • Output Tube(s):JJ E34L (2)
  • Rectifier Tube:None - Solid-State Rectified
  • Transformers:Power - Plexi / 800 50W (7020850), Output - Plexi /800 50W (7021850), Choke - Plexi / 800 Choke (7022800)
  • Speakers:None
  • Cabinet:British 800 / 900 Head Shell Cabinet
  • Hardware:British 800 Small Parts Kit, British 800 Chassis, Front & Rear Faceplates, 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:

British 800 Schematic
British 800 Wiring Diagram

Ratings & Reviews

3 reviews

  • 3 stars
  • 0 reviews
  • 2 stars
  • 0 reviews
  • 1 star
  • 0 reviews
9/1/2021 8:31 am

Great kit, however.....

by Jesse Yasaitis -

First of all the customer service is second to none. Andy is a wealth of knowledge regarding everything Mojotone and replies very quickly. That being said, the voltages in this amp are unrealistic. Please look up voltages for a JCM800 before you get concerned about a lack of voltage around the phase inverter and the XA, XB, XC, etc. Also, I used a 180K resistor before the diode for the negative voltage for the bias circuit to get the -60.

8/30/2021 7:59 pm

Good but two little details

by Moojoe -

This is mostly a nice kit, but a couple small notes: You will need one extra resistor to get the right bias (Mojo has been giving a 10K pot with a 47K resistor for years now, but the 800s used 22K pots with 56K or 47K resistors. So the kit biases too hot unless you switch to 56K or a higher-range pot). Second, the faceplate's holes are drilled wider than the chassis holes so the plate won't sit flat. To fix this you'll either be filing/drilling or gluing down the faceplate (which can mess up its finish because it's reverse-engraved).