Ampman72's Early 70's Marshall Page
The purpose of this website is to take a closer look at the Marshall amps made between 1969 and 1975, which are sometimes referred to as metal face or aluminum panel Marshalls. The coveted plexiglass panel amps (1964-1968) are now far out of reach of the budget of the working musician. I will mainly concentrate on the 50 watt lead, model 1987, and the 100 watt super lead, model 1959 from the early 70's period. I definitely have a theme going here.
These amplifiers, with the exception of a few capacitors and resistors, are schematically identical to their Plexi counterparts. When these aluminum panel Marshalls have had all of the eighties era modifications removed (master volume, effects loop, extra gain stages, etc) and good quality tubes installed and biased properly, they have a tone all their own; different but equal to that of the plexiglass-paneled amps.
The 1974 model 1987 JMP MKII 50 watt lead
I bought this amp in the fall of 1993 from a music store in Charlotte, NC. This amplifier was completely original, with the original GE 6550s in it. I had it converted to EL34 and he changed the phase inverter resistors to 150K. I sold it to a guitar buddy 1996. He still has it and will not sell it back to me. It is the "best" one. A fantastic sounding amp with lots of break up. B+ is 407 volts. Original Drake Transformers.
The 1974 model 1959 MKII 100 Watt super lead
This one I bought in the summer of 1995 from a man who lived east of Raleigh, NC. It had a pre phase inverter master volume and the typical box fan installed. Luckily, there was no huge gaping hole cut in the side of the box. I took these modifications out and set it up for EL34s (added 47K resistor). It now has the excellent sounding brown base Svetlana EL34s. This amp has plenty of clean headroom, but breaks up nicely when pushed. B+ is around 440 volts. Original Dagnall transformers.
The 1974 model 1987 JMP MKII 50 Watt lead modified by Harry Kolbe
In Sept. 2001, I found an ad in the Trading Post (local bargain hunter paper) for a 1974 JMP MKII modified by Harry Kolbe. I drove up to Greensboro to get it. Original trannies, three switches, PCB. Harry has done a number of mods to it, including a master volume and additional gain knobs and mode switches. It's a screamer. Too much gain for me. Instead of removing the mod and rebuilding it, I sold it to another close friend, who appreciated its high gain sound and wouldn't change a thing about it. It has the original Drake Transformers.
The 1972 model 1987 JMP 50 Watt lead formerly owned by Audley Freed of the Black Crows
This amplifier was also sold to me by the same guy who had the Kolbe modified '74, a few months later, Nov 2001. He told me he had a '72 that he might sell and I told him I would buy it, sight unseen. It had a 2204 type master volume, an effects loop and blew fuses once it was turned past five. I removed the MV and the effects loop. It has various EL34s in it. The power transformer had been replaced with a late 70's Drake 1202-324 and B+ is a high 485 volts, giving it more bass and more clean headroom than most 50 watters from this period. This amp has been on the road with me and is my main live amp. The OT is the the original Drake.
The 1972 model 1987/T 50W tremolo
I got this tremolo model chassis in a home made black small box last summer as a project amp on flea-bay. There was a PPIV MV installed and the tremolo section was completely gutted. V1 was changed to a split cathode configuration. According to the paper tag on the top of the chassis, this was originally in a combo amp. The non original caps were restored with phillips "mustard" caps and the MV has been removed. It has been wired to the old 1987/T schematic (including among other things the 56 K slope resistor and the shared cathode configuration on V1, more like the 1986 bass) and I have yet to rebuild the tremolo circuit, but this will happen soon. This amp has the classic rock sound. I have installed the Marstran 139 OT, and was blown away by the volume, and quality on tone of this amplifier. Contact Brian Wallace through the link at the end of the page. The head cabinet was constructed by Ray Domzalaski and I have bigger pictures upon request. He does excellent wood and tolex work. The Drake PT is intact and provides 443 Volts DC after rectification. The shared cathode circuit gives this amp a much earlier tone than the split cathode amps on this page.
The 1974 model 1987 JMP MKII 50 watt lead
A fender fanatic friend bought this head on e-bay spring 2003, which I converted over to EL34s from 6550s. When I heard he bought another old fender amp and wanted to throw this on e-bay with no reserve, I acted fast. I couldn't let it get away. I picked it up right after New Year's, Jan. 2004. There was a master volume mod that worked like a 2204 with preamp volume being volume 2 and master volume being volume 1. This left a fuzzy, buzzing distortion sound. I took this modification out and wired it back to stock 1987 spec. What an amazing tone! This one now has that "chunky growl" that only the non-master amps can create. This amp has the original drake transformers and B+ is only 376 Volts, so it "gives it up" very easily. Svetlana output tubes.
The 1970 model 1960A The 1971 model 1960A The 1973 model 1960A The 1973 model 1960B
The 1974 model 1960B The 1975 model 1960A The 1972 model 1960A
pic coming soon!
The two cabinets on the upper left were found a long time ago in a galaxy far, far away (the '70 in '93 and the '71 in '95 ) in shambles with no original speakers. The tolex was removed and they were spray painted black. The '71 had Radio Shack grill cloth. But, they were cheap. Mojo Music did the tolex and grill cloth job on these. The '70 has no speakers, the '71 has two green back G12M-25s from '71 and two RI G12M-25s.
The '73 1960A cabinet has the original G12M-25s in it. The 1973 1960 B has no speakers. The 1974 1960B has one '74 G12M-25 cream back, a '72 green back G12M-25 and two RI G12M-25s. The '75 has two '78 G12M-25s and two RI G12M-25s. All of these came in '07-'08. The other basketweave B cab is not a Marshall but is in fact a copy of a Bogner 4X12 that I put salt and pepper grill on to match the '71.
Links
http://myspace.com/secretmountainjamsociety
http://vintageamps.com This is the Plexi Palace website. There are numerous forums about great vintage amps. I hang out here pretty often.
http://marstran.com This is Brian Wallace's excellent website, home of the Historic Data Base and other tech info. The HDB has over 120 amps in it, including JTM45, JTM50 and JMP50 from 1962-1980. There is a link for Wallace amplification, his amplifiers and transformers.
http://richtone.com Home of Richtone mandolins.; He has made over 100 instruments. You can find him at shows, bluegrass festivals, old time fiddlers conventions and house parties playing his mandolin.