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  1. R

    Is it normal for my JMP 50's to have a loud clean with the volume knobs all the way off?

    I have a 72 JMP 50 and a 76 JMP 50. Both have Lar Mar PPIMV mods. If I run the PPIMV all the way full on both amps, even if I have the volume knob on 0, I still get a loud clean tone, enough to fill the basement that I play in. This can't be normal can it? I used to own a reissue 100 watt...
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    What hot rodded mod options to do I have with an extra preamp tube installed?

    It sounds decent. My 72 is a lot more aggressive with more gain, but that is because it has a 5000 bright cap. This one is a lot more mellow. I don't like it anywhere below 7. I think because it has no bright cap, anywhere from 1-5 sounds like crap to me. I only play Marshall's cranked up...
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    What hot rodded mod options to do I have with an extra preamp tube installed?

    I'm trying to figure out what to do with the amp overall. I originally bought it thinking it was hot rodded but realized after I received it that it's a stock JMP 50 with an added tube effects loop and master volume. The master is a pre phase so it lowers the gain when turning it down which is...
  4. R

    What hot rodded mod options to do I have with an extra preamp tube installed?

    The amp is already modded with an extra tube, just not in the way I would like, so keeping it original isn't a concern.
  5. R

    What hot rodded mod options to do I have with an extra preamp tube installed?

    I thought those work better on 2203/2204's?
  6. R

    What hot rodded mod options to do I have with an extra preamp tube installed?

    My '76 JMP 50 has a extra preamp tube because it has a tube buffered effects loop. Also has a pre phase master volume. I feel like I can take advantage of this and get the amp remodded into some kind of hot rodded marshall like a Jose, etc. I was hoping to get some potential options on what...
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    Anyone regret buying a vintage amp and wish they went with something newer?

    Last year I went on a vintage marshall buying spree and ended up with three amps. '72 JMP 50, '76 JMP 50, and an '81 JMP 2203 I didn't pay online prices for them, but not too far off. I'm fortunate to have them, although they aren't all original. Changed caps, one of them has a non...
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    Lost EVH/Jose collaboration amp. Any further details?

    In the James Brown interview on Tone Talk, he talks about the original plan for the 5150 amp. Ed was supposed to supply them with an amp that he and Jose were working on together, and they were supposed to copy it. They waited and waited, and it never showed up. Eventually they went ahead and...
  9. R

    Can anyone help me figure out why my '72 50 watt has so much more gain than my '76 50 watt?

    Not looking to stir up crap to be honest. Was just trying to get more info on what I have.
  10. R

    Can anyone help me figure out why my '72 50 watt has so much more gain than my '76 50 watt?

    Man, people are taking stuff way too seriously. It's just some questions about a couple of old guitar amps. When the first few replies are people basically telling me they are too busy, learn it yourself, or in other words 'pound sand', or trying to scour post history to try to get one over on...
  11. R

    Can anyone help me figure out why my '72 50 watt has so much more gain than my '76 50 watt?

    I wouldn't even know where to begin. I know nothing about electronics.
  12. R

    Can anyone help me figure out why my '72 50 watt has so much more gain than my '76 50 watt?

    Well that's why I'm here. Hopefully someone can help out.
  13. R

    Can anyone help me figure out why my '72 50 watt has so much more gain than my '76 50 watt?

    I own a '72 1987 and '76 1987. Both amps had a pre phase master installed before I got them, but since I use a Fryette PS100 I don't use them, I leave them on max at all times. I know both amps are not stock circuit wise and have had a few changes but I am not 100% clear on what changed and...
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    Is there a site that explains every section of a Plexi/Metal Panel circuit board?

    I know nothing about electronics. Capacitors, resistors, etc. All foreign to me. However, I would like to learn more about the internals of amplifiers so that I can be at least somewhat informed when buying this stuff. Are there any sites, videos, etc that show a picture of a Marshall...
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    Can someone explain why this is happening when I use a Fryette PS100?

    I have 2 JMP 1987's from the early/mid 70's. Both have a master volume installed prior to me getting them (Pre PI). Since I have the Fryette, I run the amps with the master volume all the way on full, essentially out of the circuit. I set the regular volume on the amps on 7-8. When I do...
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    Does this JMP 50 look ok?

    Makes me realize that vintage amps are too much of a risk. I got these all locally where there was no opportunity to open the amp. It was all based on if you liked how it sounded and you bought as is. Not sure what I'm going to do with these since I bought them as investment in addition to...
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    Does this JMP 50 look ok?

    So I'm assuming the switched out power transformer would heavily lower the amp's value? Given today's prices, what do you think a fair price for this amp would be with the replaced transformer? I see the early 70's amps going for roughly $4k and up these days. I didn't pay that price, but am...
  18. R

    Does this JMP 50 look ok?

    I do play it, I just am curious to know what I have. I purchased the amp for 2 reasons. I liked the way it sounded, and as somewhat of an investment. I know the price on these will never go down, only up. Even with mods. Still looking for an answer regarding the polarity switch and "death cap"
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    Does this JMP 50 look ok?

    Oh one more thing that came to mind. I noticed on other pictures of early 70's Marshalls, that one side of the board has a square black thing attached. On this one it's missing, but the screw for it is there. What does this thing do, and is it normal for it to not be there?
  20. R

    Does this JMP 50 look ok?

    You're right, I guess I do. I'm a player, I'm not a tech, nor do I have any knowledge about the internal workings of tube amps or electronics. All I know is, that after lurking on these forums, whenever someone has similar questions, everyone tells them "Post screen shots of the guts and we'll...

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