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'71 Marshall JMP 50 opinions

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8/29/2000 3:13 AM

'71 Marshall JMP 50 opinions

Hi,

I have taken the plunge on my first vintage Marshall. Even when I started playing in the 70's I always went for the new stuff, at that time a Princeton Reverb. Never played a Marshall from any year other than the 90s versions, DSL, TSL, 6100, and an Eighties JCM800. Currently have a couple Two Rocks, a Bogner Ecstasy and thought this JMP would be the ticket for the Vintage Marshall type tone and when dimed will put out some nice distortion. Would appreciate some feedback on how these babies sound and what I am to expect and since this has four inputs what is the correct way to "jump" the channels.

Thanks,

Steve

8/29/2000 3:23 AM

Steve,
Along with Tweed Bassmans, JTM-45s, these amps are the holy grail. They are clean, but when you crank 'em you get a nice dynamic crunch that will put goosbumps on ya'. There is no correct way to jumper the channels. If you plug in to high input of the muddy channel and jumper over to the high input of the clean channel(or the other way around) you can mix the channels to suit your taste. Things will get kind of muddy on the bottom if you crank both channels all the way. To avoid this plug into the low input of the mud channel and jumper over to the high input(or low) of the bright channel and mix 'em. Depends on your guitar too. I plug my Tele into the high inputs and let her rip......can you say Led Zepplin?

Peter S

8/29/2000 3:36 AM

quote:
"I have taken the plunge on my first vintage Marshall."

Hurray! Congrat's to you!

quote:
"what is the correct way to "jump" the channels."

I use a small jumper between lower (low sens.) input of I and the upper (high sens.) input of II, and plug the guitar into the upper input of I.
You could invert them, though. Try different combinations and see what you like.

Good Luck and have fun!

-Dave

8/29/2000 4:32 AM
steve snider	Thanks Guys! I know this amp differs from the 1959 SLP but was wondering in what way. Steve

8/29/2000 5:32 AM

Steve,
The 1959SLP is a reissue amp. The circuit is pretty much the same as the one in yours except they use an 829ohm cathode resistor on the cathode of the first gain stage(bypassed by a .68) in the bright channel. Thsi gives the amp more gain and a fuller tone. The reissues are also pc board construction and use cheaper signal circuit components. Your amp is handwired and uses a 2.7k cathode resistor on the bright channel with the .68 bypass cap. You could install an 820ohm resistor if your not too worried about keeping it totally original. In the Kimerik k-50 amps I use an 820ohm on both cathodes, because I like the extra gain and fullness. Of course the 1959 is a hundred watt amp which has a different sound than the 50 watters and it's slightly louder too. These are great amps!

Peter S

8/29/2000 11:38 AM

Steve, I agree with pete on the 820 ohm resistors on both cathodes of the first preamp tube. Another way to run the amp is with a Y-cord into both top inputs. Also, if the amp hasn't been gone over you might want to take to someone to check out. I'd guess there's probably a better than 50/50 chance it's been modded with something or needs caps. Congratulations on a cool purchase. I've got a bunch of old Marshalls and my favorite is a '73 50 watt lead with a PCB board and a .68 cap on the presence control. Fat, loud and clear!! Mark

8/29/2000 12:39 PM

I've had two of these amps...a '70 and a '71.
Also an older '67 plexi 50 watt. The '67 had the warmest tone of the three and was not as loud as the '70 or '71. I still have the '70 and love it...it's my best Marshall but to loud to play at home or at the Church gigs I play mostly these days. A THD Hot Plate is going to be next purchase. I use Tesla EL 34's in mine. I've tried Mullard, RCA and GE pre amp tubes...I like the RCA best. The Mullards were a little to dark sounding and the GE a little to bright. The RCA sounds best in my amp. Lew

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