British Style 45W Amplifier Kit


Cabinet and Speaker Sold Separately (Add Below)
SKU: G1B45238
Weight: 24.5 lb
Sale Unit: Piece

In Stock


Amp Kit Difficulty Level


If this kit shows as out of stock please 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 was the first amplifier Marshall® ever built, based off of the 5F6A circuit. Favored by blues and rock guitarists, this amp can produce a warm sustain and elegant clean tones, with a pronounced rectifier "sag." Played by guitar greats such as Angus Young and Gary Moore.

  • Class Type:AB All Tube Amplifier
  • Output:~45 Watts
  • Circuit:M45
  • Bias Type:Fixed Bias with an adjustable potentiometer
  • Build Time:~6 hours
  • Preamp Tubes: ECC83/12AX7 (3)
  • Output Tube(s): E34L (2)
  • Rectifier Tube: 5AR4 / GZ34
  • Transformers:Power - 45 (7020300), Output - 45 (7021300), Choke - (MOJO777)
  • Hardware:British 45 Small Parts Kit, British 45 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:

Mojotone British 45 watt Schematic

Mojotone British 45 watt Wiring Diagram

Mojotone British 45 watt Wiring Diagram with Master Volume Mod

Videos Featuring This Product

Ratings & Reviews

5 reviews

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4/6/2023 11:50 am

JTM45 Rocks !!!!!!!!

by Marshall -

The wife and I are both retired !! The wife has vast a array of craft talent !! Eg,. She does Stain Glass , Wood Burning , Etch Glass , Expert Knitter , etc !!! I've played guitar 🎸 for the past 45 years , Aircraft / Car mechanic !! I decided to build the JTM45, so I can sit and chat with wife at her craft table !! Nevertheless , the JTM45 was an exciting and fun amp build !! Mojotone stepped up to the plate in every aspect of troubleshooting / sending me a few replacement parts without a sigh 😕 !! I didn't use the tube retainers , for if a tube is loose in its socket , then the socket needs replacing !! I utilized Rob Robinette website in Amp Startup / Troubleshooting guide , which I highly recommend !!! The Amp is going to be gifted to a Disabled Vet, and I'll be moving on to another Mojotone Amp kit build soon !! For now (( Think 🤔 Smart / Think 🤔 Safe )) while building your Mojotone Amp kit !!

1/1/2023 5:52 pm

Highly addictive hobby

by Darryl Carstensen -

This is my third Mojotone kit, and hopefully not my last. I have built over twenty amps in the last two decades sourcing individual parts from multiple vendors. Mojotone makes it so much easier. They use excellent parts that are well organized. I have been thoroughly impressed with the transformers and chassis. This British kit was the only one that I needed tech support. I had a problem with power tubes that were mismatched. They corrected it quickly, and my amp is sounding fantastic. As I said earlier, this won't be my last kit. Mojo is a first rate company.