This amp build follows the 5F6A schematic, which was borrowed by Jim Marshall for the JTM-45 circuit. Blackface reverb is added with the control knob on the back panel. The quad of 6L6 power tubes drive a vintage ‘60s Twin Reverb output transformer,
       
     
This amp build follows the 5F6A schematic, which was borrowed by Jim Marshall for the JTM-45 circuit. Blackface reverb is added with the control knob on the back panel. The quad of 6L6 power tubes drive a vintage ‘60s Twin Reverb output transformer,
       
     
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This amp build follows the 5F6A schematic, which was borrowed by Jim Marshall for the JTM-45 circuit. Blackface reverb is added with the control knob on the back panel. The quad of 6L6 power tubes drive a vintage ‘60s Twin Reverb output transformer, wound by Schumacher Transformers (i.e. the 606 EIA code). Two control switches on the front panel allow the first tube bias to be switched to a later JTM-45 value and the negative feedback to be changed.