In the fall of 1962 the Marshall JTM45, which is based on the Fender 5F6A, saw the light of the day and has been enjoyed by musicians and guitarists around the world ever since. Even though there have been minor changes to the circuit over the years, the JTM45 has remained faithful to its origins.
The TT JT45 kit is based on the reissue version of the JTM45 with the following modifications:
- The used output transformer offers a dual-primary winding and can be used for both EL34 and KT66 tubes. Only a different wiring of the primary connections is necessary.
- The standby is not a pure "mute". The resistor R107 is used to protects the components, but this has the consequence that even in standby a minimal current flows through the output tubes
- The resistors R108 and R109 in the leads to the rectifier tube provide a better matching of the power transformer to the rectifier tube. Especially with 5AR4 / GZ34 tubes from current productions we noticed again and again that they work sensitive in JTM45 amplifiers due to the often too low internal resistance of the high voltage winding. This problem is usually eliminated by the two mentioned resistors.
Schematic and Layout Version 2021 incl. Black-Flag Mod
You can get the JT45 kit in the Online-Shop and many other items which you might need for this amp like faceplates and headshells:
Care is necessary during construction! The voltages used in this amp are potentially fatal. This amp is NOT a beginner's project!
A successful build requires that you can read (and understand!) a schematic diagram, you know how to use various measuring devices, and you have some experience working with voltages over 60V.
Build with the use of the EZ-Board tbez-077