Master Volume (JCM800) Series Mods

The following modifications should work for both the 'Master Volume' series of amplifiers and the 'JCM800' series of amplifiers both built by Marshall. Cosmetically the two are quite different but internally the circuits are the same.

• 2203 / 2204 Tonestack Mod
• 2203 / 2204 Tone Mod
   
• 2205 / 4210 Gain Mod