Marshall JMD:1 fans ?

Discussion in 'Marshall Amps' started by Johnversloe, Nov 30, 2020.

  1. Jethro Rocker

    Jethro Rocker Well-Known Member Silver Supporting Member

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    It would appear so.
    The manual does state what it seems to be doing tho. Seems to make more sonic sense in the preamp than as a PI to me.
    Perhaps manual meant what the original amps did. Weird
     
  2. BGLeduc

    BGLeduc New Member

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    Right. The manual describes what is being modeled.
     
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  3. CROWEMAG

    CROWEMAG Well-Known Member

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    Blanket statement. Just the concept bothers me for some reason. I have also never played one I truly liked other than the sweet, sweet chorus on the JC-120. My bias towards amps with built in effects may blind me to potentially cool options.....but I say I will bow out and let those of you that like them have at it. Hahahaha. It's just one of those "things" for me.

    I also do not use a ton of effects. Chorus, delay maybe....OD always.
     
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  4. Kinkless Tetrode

    Kinkless Tetrode Well-Known Member

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    I don't use the built in effects much. Maybe a pinch of reverb or a dash of delay when building a preset. It would be nice if it had a rotating speaker effect for those times when I want to play Badge though. Maybe it does but I don't know how to do it?

    Most of the time I just use it like a standard Marshall tube amp. It has a loop, and it responds to putting a boost or a wah in front like a standard tube amp. But I don't use pedals much, anyway. Hardly ever. It could be used as a pedal platform I'm sure. It has the DSL, JVM, and JMP1, clean channel models and it also has a flat EQ preamp model.

    It has the JVM and DSL overdrive channels, as well as the Haze clean channel (plexi preamp signal path) with a KoT type pedal in front, too though.
     
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  5. LPMarshall hack

    LPMarshall hack Well-Known Member

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    So does the JMP-1 really sound like it does on the JMD? On the JMD, that preset is so scooped and thin. But people rave about the JMP-1.
     
  6. CROWEMAG

    CROWEMAG Well-Known Member

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    I have never played the MD but I can say the MP 1 is a thing of beauty. I would never call it thin or scooped.....unless you dump the mids....but then why are you playing a Marshall?
     
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  7. Jethro Rocker

    Jethro Rocker Well-Known Member Silver Supporting Member

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    It sounds pretty good to me, at least basic chorus flange delay. To be fair I haven't really run through it properly yet so my opinion is reserved for now. I am not against trying out cool things if they work well, Thus the whole JMD concept!
    I may not use any except for the gate. I even have that in my multi fx so I may find all of them useless!
    BUt as far as amps go it is a winner regardless of that!
     
  8. Dogs of Doom

    Dogs of Doom Moderator Staff Member

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    the JMP-1, if all tones are set to "0", has the tonestack replica of a JCM900 SLX. It has a scoop button, as well as a bass shift.

    Marshall doesn't always use the best tones to model. I think of how terrible the JVM sounds in the CODE. If that's all you had to go by, you'd think the JVM is a dark, dull sounding amp. They did it right on the JMD, but, the CODE, blech!

    The problem there, is that the JMD sounds good, if you add presence & treble, whereas, the CODE can not sound so good when you go adding those high frequencies...

    The reason, I use "0", as a base point, is that "0" is like the knobs on a JCM900 on "10". The tones on the JMD are active, so, zero is like having a passive knob wide-open. +6 (max) is a boost & -6 is subtraction. In a passive tonestack, the pot at 10, is wide-open & everything else is subtraction...
     
  9. Dogs of Doom

    Dogs of Doom Moderator Staff Member

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    IMO, while the FX in the amp, might not be anything to write home to mother about, it is adequate to get you through the night, if that's all you've got.

    The reverb is decent & delay. Probably better reverb than most other amp's, like the DSL/TSL, etc.
     
  10. LPMarshall hack

    LPMarshall hack Well-Known Member

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    I don't have an actual JVM to compare, but I think the JVM presets (I think 10 and 16) on the JMD are awesome. As for the the JCM 800 preset (#6)...I'm not too impressed. Doesn't seem to have the grunt of a real 800. Still sounds good, just maybe not 800 good. What do you JMD guys think of that channel?
     
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  11. marshallmellowed

    marshallmellowed Well-Known Member

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    I found that reducing the negative feedback (increasing the resistor value) improved the overall sound of my JMD (IMO).
     
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  12. Dogs of Doom

    Dogs of Doom Moderator Staff Member

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    do you remember what the values were? (before/after)

    That's one thing I miss about the old site, was the "social groups". The JMD:1 group, was a great little resource. Member @MKB had quite a few mod's he did. Many that I've wanted to do, if I ever get around to it. Luckily, he posted them over at the Roadhouse, so, you can always hunt them down over there, if you're so inclined.

    A lot of them made sense, like changing the signal level going into the power amp, reducing the XLR out a few DB, etc.
     
    Last edited: Dec 2, 2020
  13. Dogs of Doom

    Dogs of Doom Moderator Staff Member

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    this is from a TSL mod site, where the guy made a mod to the NFB:

     
  14. Jethro Rocker

    Jethro Rocker Well-Known Member Silver Supporting Member

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    I have to go play. Personally, I just want ti to sound good, not necessarily model specific amps. My guess is not much has the 800 grunt except an 800 amd the odd other amp.
     
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  15. Dogs of Doom

    Dogs of Doom Moderator Staff Member

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    I found a thread where @MKB posted the mod's. Not sure if this is all of them, but:

    1) Decrease the value of C113 and C114 on the input PCB to 1uF. This was done because I felt the low end overdrive of the amp was driven a bit hard and made the amp tone a bit indistinct on the low strings on most presets. I found I could take an EQ and drop the lows a bit, and this made a big difference with humbucker guitars. Lowering this value of these caps basically did the same thing, and works very well to clean up the tone of the low strings.

    2) Increase the value of R21 on the main PCB to 68k. With the reissue Mullards in my JMD501, it was a bit difficult to get enough signal into the power tubes to really drive them to clipping under all reasonable preamp volume settings. It seemed sometimes live I couldn't get enough control out of the master volume. Increasing this resistor increased the signal into the power amp, and basically set the same volume when the master was on around 3 than it was on 6 before.

    3) I intend sometime to increase the value of R7 on the main PCB, this will lower the signal from the direct out (which is too hot in some situations). I haven't done this yet as the boards I currently work with can handle that signal level, and I haven't calculated how much to increase it to get the right resistor value.

    4) Another mod would be to install a switch that would disconnect pin 1 of CON2 on the main PCB from ground. This would serve as a ground lift to the direct out; the lack of this has caused me many issues live and I have to use a ground lift on the power cable to cut the ground loops. Unfortunately this mod will require a hole to be drilled in the chassis, so it is nonreversible.

    5) Am also thinking about adding an external fuse holder in place of F1 on the main PCB, that way the B+ fuse could be replaced without removing the amp chassis. This is also nonreversible.
     
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  16. Jethro Rocker

    Jethro Rocker Well-Known Member Silver Supporting Member

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  17. marshallmellowed

    marshallmellowed Well-Known Member

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    Don't recall what value I settled on. The stock resistor is still in place, I just added some series resistance at the transformer lead.
     
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  18. JSJ900

    JSJ900 Well-Known Member

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    I got the 50 watt head years ago for $400. I’ve had no issues, but It’s only been moved a few times. mine didn’t come with a footswitch. I use it with a 4 cable method and Boss GT-8 (amp and cab models turned off on GT8). I can I can switch all my time based effects in the GT8 and change to up to 128 (I think) JMD1 programs with one foot button on the GT8. The Gt8s loop goes to a BOSS SD1, The JMd and a BOSS GE7 and back to the GT8. The sends go back to the JMD and a slave JCM 900 Mark1. Both heads go into 1960 4x12s. The effects are decent on the JMD1, but I like the gate, so it’s always in use and the GT8 handles all the digital reverb, delay and Chorus. I think it sounds pretty good, not much noise, was relatively cheap and extremely versatile. I think you’ll like it.
     
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  19. ❤️gfilan428

    ❤️gfilan428 New Member

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    Have head version, previously had the combo. I remember seeing a demo on jmd1 when they first came out and was impressed by Doug Aldrich endorsement. You have to spend time learning this amp, it can sound great or like crap on each preset. Really responsive eq and I love the gate. I think what a lot of people do (myself included) is often go to heavy on the gain, on some presets 12 o’clock is too much, others you can push it up. I think they are a killer amp and most people would be surprised how great they can sound if they invest a kittle time learning how to dial it in.
     
  20. marshallmellowed

    marshallmellowed Well-Known Member

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    This is very true. On some models you can hear a distinct change on the gain dial at certain levels, where it can go from very detailed to slightly mushy. I treat each model as a "sound", not focusing on what it was supposedly modeled after. If I like what I hear, I use it, and I only use a couple of the models to cover everything I need.
     
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