This was an awesome rig that I owned from late 1979 through to end of 1985. Played both Guitar and Bass through it and whilst it was a Marshall Super Bass JMP 100 the tone was a bit more mellow compared to the Super Lead of the same era. Damn loud and barely played past '1' on the volume knob as there were no master volumes back when it was built which I reckon might have been late 1960's,and probably one of the 1st metal front versions that were introduced after the original plexi's. The quad box was an Australian made 'Wasp' and loaded with 4 x 12" Green Back Celestions. With a Boss Overdrive and playing my Ibanez Explorer the controllable feedback it generated cannot be described as you truly have to witness such first hand to truly appreciate. Selling this rig was one of my biggest regrets but they are no longer practical in this modern era of low db levels at venues these days, hence why I now have combos.
Last shot has me on the far left playing Bass through the Marshall circa 1984.