amp

These Marshall amplifiers are pretty classic, them came in a Super Bass 100 Watt and Super Lead. The Super Lead was the amp used by Hendrix, although many musicians inc. Hendrix often preferred the Super Bass for guitar! I obtained two Super Bass Amps over the last number of years and they were manufactured way back in 1974. The Serial No for the Amps are SB/A 22024 F & SB/A 22078 F so they must have been made around the same time! To check out the year of your Marshall amplifier check it out here: http://www.oocities.org/SunsetStrip/Bistro/3491/dating.html

However, one of them is non functioning, I was told by the guy in the shop that it died as a result of a failure in the bias supply, perhaps combined with the poor condition of the capacitors which couple the stages together, especially the driver plate to the output tube grid. And when these leak, it causes huge currents to flow in the output tubes, and could have burned up the output transformer. As it turns out I was only interested in getting a few spare control knobs for my JMP but upon seeing the amp I took it from the guy for only £35 Irl. I recently sent it to a really good tech. To check it out. Turns out just a few tubes had gone, I also got the power supply rewired from 220V to 240V, put on an Euro power socket and got the impedance selectable switch working again. So the amp is now as good as new! I also stripped off the old worn black protective cloth which was in tatters, scraped and sanded off the glue and painted it up to a nice gloss red, which goes smashing with my 2 x 12" bass cabinet that I designed .

Performance

Normally, these amplifiers are quite bullet-proof, and can take tons of abuse and survive massive beer spills (Thanks to Terry for testing this out on numerous occasions). The Marshall JMP 100 Coupled with the original 4 x 12" Marshall Bass Cab, really punches out that Bass with deep lows and a punchy Mid Range. I was initially worried about lugging this bulky heavy Amp and Cab around (esp. the Cab as it's really awkward!) as I felt all the gigging may damage the tubes esp. after a gig when the tubes are cooling down, but to my surprise this amp is real rugged and can take a lot of abuse. I guess if it's survived this long, then it will survive anything. As for Volume the Marshall outstrips my old Peavey Mark IV Bass Head in all aspects. The Marshall has a real nice Bass Sound that goes down real well with the Blues rock that I play.

Though I never experienced any real problems with the Amp, though I have found when the Cab is placed on Stone surfaces (concrete floors, stone tiles) the Bass sound seems to distort and appear to be muddied to those around the CAB, however to the audience the sound appears to be O.K., does anyone know how this happens?? Let me know if you've experienced similar problems!!

Modifications

The Original Amp and Cab were covered in a Black Covering, however somewhere down the line this was stripped off (or what was left of it after years of gigging!) and both the Amp Head and CAB were varnished (quite poorly) in a rosewood finish. Both the Voltage & Speaker Impedance settings have also been hardwired to suit the CAB, maybe someone had a nasty experience before if they set-up the wrong speaker impedance?? The power cable plug/socket has been changed to a more modern type.