This amp started life as a 1989 Marshall JCM800 2204 EL-34 50 watt.
It was completely gutted and rebuilt by John Suhr in December 2008 with a new board featuring the PT100 circuit. He also added a three position Whomp II switch, Resonance knob and his excellent effects loop with a level switch for pedals. It retains the original Marshall transformers. It also has a new Plexi rear panel that JS built. Although it is a single channel amp, both inputs have different gain stages and will cover everything from Plexi cleans to hard rock tones. It also features a footswitchable boost (black box marked "Solo" in pic) that can be adjusted with a trim pot on the board.
It was recently completely retubed and given a clean bill of health by John.
John has stated that he is no longer doing Marshall mods and there are no other like this.
It has a new custom Mojo small box style cab and Suhr Marshall badge (one of a kind). I also reached out to John recently to confirm that he did in fact do the work on this amp himself, I have attached a screen capture of the conversation as a courtesy to potential buyers looking for confirmation as I always know with modded amps, I like to hear proof right from the source! :)
It definitely retains that classic JCM800 punch but with MUCH more gain available and the best loop in the business. It takes pedals well and cleans up great when rolled back. Similar to a PT100 but this one has more Marshall flavor to it still and John confirmed that this build was a prototype version for the second version of the Suhr PT100 amplifier (prior to the 3rd/latest version known as the "signature edition" which has the plexi transformers, midi etc.) and this amp is a one of a kind.
Just a great amp.