Fun old Marshall amps - what are they?

[RJ Guitars]

Hello All,

I've recently been given three different amps... two of them for repair and return to the owner, the third is a gift to me.

All I really know about them is that they are from the mid 70's. The top one is a clone of the 2nd one, the 2nd one is a 50 watt and the bottom one is a 100 watt. I don't know a lot about Marshall history so I am fishing for info here...

The 50 watt belonged to the other guitar player (BW) in a band I played in back in 1975. It was an amazing amp and I remember it as the best sounding amp ever... it had awesome tone and it was louder than my 150 Watt Sunn amp. (sollid state). He blew the OPT when it was fairly new and replaced it with a HiFi ultra linear OT (notice big fat tranny in photo... maybe or maybe not what made it sound so good.

My buddy BW (only 17 at the time) cloned the 50 watter (top amp) and that's what I played through for a while... this is his gift to me 30 years later... It was a cool amp but it never sounded as good as his Marshall - it had the same Ultra Linear OPT by the way.

The 100 watter also belongs to BW... he bought it in England around 1977 when he was an exchange student at Oxnard University... It strikes me that the power tranny in the 100 is smaller than the 50 watter... just at a glance.

Anyway, none of them are working and I'm curious if anybody can tell me more about them? The 50 says it is a MKII - Is it anything special? He said it has had 6550 tubes since it was new. Is that common? The 100 says Super Lead 100 and it didn't have any tubes in it when I got it. I put 4 EL34's in to test it out... the light came on and the tube heaters worked, but no hum... again is there anything special about it or that I need to know before I work on it? I have some close up photos if they are useful to anyone.

They both light up the pilot light although I haven't even begun to check voltages yet... it should be great fun.

thanks

rj

[ampgeek]

Nice!!!
Here is a great site for Marshall amp history:

http://www.drtube.com/marshall.htm

Front panels indicate that they are JMP's.

Have fun!!
Dave O.

[sliberty]

I am guessing that the middle one is a JMP50, and the bottom one is a 1959 Super Lead (since it says Super Lead on the back).

[BBQLS1]

Nope, they are junk. Send them to me and I'll dispose of them for you, I'll even pay the shipping because I feel bad you are stuck with them.


I know, I'm a swell guy.

[Cameron]

Hello All,

I've recently been given three different amps... two of them for repair and return to the owner, the third is a gift to me.

All I really know about them is that they are from the mid 70's. The top one is a clone of the 2nd one, the 2nd one is a 50 watt and the bottom one is a 100 watt. I don't know a lot about Marshall history so I am fishing for info here...

The 50 watt belonged to the other guitar player (BW) in a band I played in back in 1975. It was an amazing amp and I remember it as the best sounding amp ever... it had awesome tone and it was louder than my 150 Watt Sunn amp. (sollid state). He blew the OPT when it was fairly new and replaced it with a HiFi ultra linear OT (notice big fat tranny in photo... maybe or maybe not what made it sound so good.

My buddy BW (only 17 at the time) cloned the 50 watter (top amp) and that's what I played through for a while... this is his gift to me 30 years later... It was a cool amp but it never sounded as good as his Marshall - it had the same Ultra Linear OPT by the way.

The 100 watter also belongs to BW... he bought it in England around 1977 when he was an exchange student at Oxnard University... It strikes me that the power tranny in the 100 is smaller than the 50 watter... just at a glance.

Anyway, none of them are working and I'm curious if anybody can tell me more about them? The 50 says it is a MKII - Is it anything special? He said it has had 6550 tubes since it was new. Is that common? The 100 says Super Lead 100 and it didn't have any tubes in it when I got it. I put 4 EL34's in to test it out... the light came on and the tube heaters worked, but no hum... again is there anything special about it or that I need to know before I work on it? I have some close up photos if they are useful to anyone.

They both light up the pilot light although I haven't even begun to check voltages yet... it should be great fun.

thanks

rj

That 100watt is one of the best Marshalls(late 68?). All the Van Halen guys will go nuts over that one , its just like Ed's. Just change the tubes. Dont change any parts if you dont need to. This amp you could easly get $2500 on ebay.

[RJ Guitars]

Nope, they are junk. Send them to me and I'll dispose of them for you, I'll even pay the shipping because I feel bad you are stuck with them.

I know, I'm a swell guy.

BBQ... Thank You so much for the generous offer.

Thank you everyone else for the info. BW will be delighted that he's he hung on to these things. I have assured him that we will get them back into form in the coming weeks.

Who knows we might just have to do a reunion tour of the old band - The Rigor Mortis Band, I'm sure you've heard of us. I seem to recall we played pretty loud but I don't really remember any other defining characteristic of the band.

I'll post again as I look for answers why these things have gone mute, or maybe when they are again singing the blues.

Thanks again

rj

[908ssp]

That 100watt is one of the best Marshalls(late 68?). All the Van Halen guys will go nuts over that one , its just like Ed's. Just change the tubes. Dont change any parts if you dont need to. This amp you could easly get $2500 on ebay.

Huh not even close.

[Deric]

I seem to recall we played pretty loud but I don't really remember any other defining characteristic of the band.

I may have played a few shows with you

[RJ Guitars]

I may have played a few shows with you [/quote]

Yeah that is entirely possible... the song set woulda been something like Johnny B. Goode, Free Bird, China Grove, Rock n' Roll Hootchie Koo, and the 20 minute Jam with drum solo...

i know we were loud and I now I seem to recall we looked really good... bell bottoms, peace signs, long thick curly hair, and of course a half dozen Junior High babes hangin around...

of course anyone who rocked with us is probably looking at the other side of 50 these days... ':?:'

rj

[Cameron]

That 100watt is one of the best Marshalls(late 68?). All the Van Halen guys will go nuts over that one , its just like Ed's. Just change the tubes. Dont change any parts if you dont need to. This amp you could easly get $2500 on ebay.

Huh not even close.

Nice response

Ahh I see......I missed the caps there on top. Its got the right iron tho....

And still $ 2500

[BluzMike]

Hello All,

I've recently been given three different amps... two of them for repair and return to the owner, the third is a gift to me.

All I really know about them is that they are from the mid 70's. The top one is a clone of the 2nd one, the 2nd one is a 50 watt and the bottom one is a 100 watt. I don't know a lot about Marshall history so I am fishing for info here...

The 50 watt belonged to the other guitar player (BW) in a band I played in back in 1975. It was an amazing amp and I remember it as the best sounding amp ever... it had awesome tone and it was louder than my 150 Watt Sunn amp. (sollid state). He blew the OPT when it was fairly new and replaced it with a HiFi ultra linear OT (notice big fat tranny in photo... maybe or maybe not what made it sound so good.

My buddy BW (only 17 at the time) cloned the 50 watter (top amp) and that's what I played through for a while... this is his gift to me 30 years later... It was a cool amp but it never sounded as good as his Marshall - it had the same Ultra Linear OPT by the way.

The 100 watter also belongs to BW... he bought it in England around 1977 when he was an exchange student at Oxnard University... It strikes me that the power tranny in the 100 is smaller than the 50 watter... just at a glance.

Anyway, none of them are working and I'm curious if anybody can tell me more about them? The 50 says it is a MKII - Is it anything special? He said it has had 6550 tubes since it was new. Is that common? The 100 says Super Lead 100 and it didn't have any tubes in it when I got it. I put 4 EL34's in to test it out... the light came on and the tube heaters worked, but no hum... again is there anything special about it or that I need to know before I work on it? I have some close up photos if they are useful to anyone.

They both light up the pilot light although I haven't even begun to check voltages yet... it should be great fun.

thanks

rj

The JMP50 has already a big cabinet (same size as the 100W), so it is '72 to '76. It has a changed OT. Originals definitely have no UL taps. If yours does, change it for a quality replacement from Brian Wallace www.marstran.com or Mercury Magnetics. Check the inside. If it still has a turret board, it is not younger than '73.

The JMP100 is definitely no plexi, so not Van Halen-ish, but has a laydown PT, so it is either from the second half of '69 or maybe from '71 according to my experience.

For both Amps you can check the serial numbers. On metal panels, the last letter stell you the year, i.e. A= 1969 and 1970, C = 1971, D = 1972 etc.

I may recommend a cap job on both amps, as they will weaken or blow anyway sooner or later, and this would cause more serious trouble. I prefer the German made F&T electrolytics, but you can also get nice radial caps from JJ or TAD.

Also, check the voltages. As today's supply voltage is higher than during the times when these amps were built, the secondaries might be too high on the 120V primary tap. If you like that soundwise is just a matter of taste, but technically high plate/screen voltages can endangerour filter and PI caps as well as tubes. Should the JMP100 be from the early 70ies, it might have 520 to 540VDC on the HT, so better be careful. You can also use a step up transfomer that lets you dial in the exact voltages you would like to have in that amp. But do not take a simple 115V to 230V step up tranny, as this might even worsen things with the varying supply voltage.

Marshalls were for some years exported to the USA with 6550s, as there were no good EL34s in production anymore. Today you might want to try out JJ E34Ls (a bit tighter and more open, as well as a bit sturdier, so good if you want to crank the amps) or Winged C EL34s.

Have fun with the Marshalls and your clone!

[RJ Guitars]

Thank you BluzMike -

These have been on the back burner for a while but I plan to get back to them as part of my winter projects.

BW told me he had changed that OPT on the 50 so you were right on in that call. Currently the lights come on for both of them and he says they both make high voltage, but no sound.

The dates you provide match up pretty well with BW's history of them.

The 50 board looked like a PC board to me and I haven't pulled the 100 out of the camp case yet.

I'll post a note again when I tear into these.

rj