How early is a Metro 12000 Super Lead supposed to break up? - UPDATED with pics!

Discussion in 'Amps and Cabs' started by Tylenol Jones, Apr 28, 2015.

  1. Tylenol Jones

    Tylenol Jones Member

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    Got a Metro Amps kit-assembled 12000 and it's my second Marshall, aside from my Bluesbreaker.

    The BB doesn't start breaking up until noon (at least) but the SL breaks up at volume 1! That's right. 1 on the Volume dial. The channels aren't jumpered and there is no OD pedal at work. Just a Joe Bonamassa Epiphone LP plugged into the top-left channel.

    It has a MV so it's quite loud when leaving the MV at 100% while on volume 1, but it strikes me as strange since the much lower-rated (wattage-wise) BB breaks up a lot later.

    Also, it has a ridiculous amount of gain.

    Is this normal?
     
    Last edited: Apr 28, 2015
  2. Charlie Dango

    Charlie Dango Member

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    I haven't played through my super lead with a humbucker yet (at least not a traditional one), but through the hottest p90 guitar I have the signal began to break up mildly around 10 o'clock, moderately bluesy between noon and 1:00, AC/DC around 2:00 and Van Halen anything after 3.
     
  3. RussB

    RussB low rent hobbyist

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    What value bright cap does it have?

    Plug into the low input for more headroom. Who built it? Got pics of the circuit? Maybe it's been hot rodded
     
  4. amphog

    amphog Member

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    Should stay cleanish till noon.
     
  5. Tylenol Jones

    Tylenol Jones Member

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    I don't have that info yet, RussB, but in the meantime, here's some info I do have which might or might not be relevant.


    • Merren trannies
    • NOS Iskra resistors
    • NOS mustard caps (almost everywhere)
    • SoZo caps for the rest
    • PEC PPIMV (post-master volume)
    • New production Svetlana EL34 tubes.
    [​IMG]

    Above is the only pic I have for now. I'll have to take it apart to get higher-quality pics.

    Something else is that it's not very bassy on the Treble pickup. But maybe that could have something to do with my LP?
     
  6. big mike

    big mike David Grissom Wannabee Gold Supporting Member

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    Normal with some not with others
    Check bias
    Check bright cap value
    Preamp tubes etc
     
  7. cugel

    cugel Supporting Member

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    i assume you mean with the ppimv dimed and the volume on 1? seems early to me. should be clean for a bit.
     
  8. Mark Robinson

    Mark Robinson Gold Supporting Member

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    It's possibly the taper of the volume pot as well. All the NMV Marshalls I've owned and used, are pretty much heavily crunchy at 4, and the texture and gain vary a lot between 4-6 then it's just more compression higher up.

    The 100 watters are louder up to 4. Rare is the NMV Marshall stock circuit, that really super clean past 2 IMO.
     
  9. big mike

    big mike David Grissom Wannabee Gold Supporting Member

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    Agree mark. Especially the 12xxx series...

    What are the eq settings?
     
  10. Blix

    Blix Supporting Member

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    Sounds a tad early, neither of the two 12xxx plexis I had were that hot.
     
  11. Tylenol Jones

    Tylenol Jones Member

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    No. The PPIMV is about halfway.
     
  12. Tylenol Jones

    Tylenol Jones Member

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    From memory, I'd say ;

    Bass - 7
    Middle - 10
    Treble - 4
    Presence - 4
    Volume - 1
    MV - 5
     
  13. big mike

    big mike David Grissom Wannabee Gold Supporting Member

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    10 in the mids is going to WAY push your gain levels up.

    Put everything at noon and see what you get.
    Cranking the mids is where the overdrive lives.
     
  14. Geetarpicker

    Geetarpicker Member

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    Heck, back when I played a '68 plexi (lead spec, 10XXX series) 100 watter I always played it with every knob dimed albeit often attenuated some. The trick to getting a clean tone was to work the guitar knobs, and the pot taper on the guitar was very important. Anyway, with my LP's volumes on about 3-5 I got great clean tones, then nice dirt from 5 on up. Even if you don't run the amp as highly cranked, I'd suggest experimenting with your guitar knobs for cleans. If your guitar volumes come on too quickly, see if you can fit new Gibson Historic potentiometers into it. I'm not sure if you need long shaft pots, as the Historics are short shaft. Anyway, try to find a 500k pot that measures out only about 1/10th it's rated value (say 50k) when it is on half. That should give you nice control of cleans without it coming on to quick, plus 50s wiring will also help.

    You might also check what value feedback resistor is in your plexi clone, and that can really change the gain on these amps considerably. Also the taper of the pots in the amp make a big difference. Typically vintage plexi controls come on quite smoothly, where as the early-mid 70s metal panel amps had pots that came on more like light switches. The pots in your clone may be of excellent quality, but the taper of the pots is different with each brand and model AND may be part of the issues you are having.
     
    Last edited: Apr 28, 2015
  15. cugel

    cugel Supporting Member

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    yeah if you bring down the mids it will most likely clean up. that mid control is where the versatility of the amp shines. from what i read both clapton and evh just swiped the control panel of their plexis in one motion: everything dimed. i dunno what jimi did. angus' settings should be out there.
     
  16. Sol

    Sol Member

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    Your amp sounds exactly like mine. No clean headroom straight to business. The key is to get that volume up and away from the effects of that treble cap. This will bring down the highs and provide you with all that midrange growl you want to hear.

    You can't compare in any way your JTM 45 with the much later circuit your using now. I have a 1964 model JMP 50 watt Lead & Bass. The pre amp is very similar to the JTM 45 and is essentially a modified Bass model with more grunt and doesn't break up until you get to about the 9 o'clock spot, and like your amp is voiced far warmer than your 12,000 + serial number amp.

    I've since got rid of the huge value cap for a 300 pf Silver Mica on the vol pot for a much tamer sound. But if I want the 'beast' back, I wire a 470 K ohm in parallel with the 300pf and away we go again.
     
  17. tone?

    tone? Member

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    My Germino Headroom 100 is like that as well.
    I sent mind to Greg and got a 460v PT put in there.
    Got it back and it's sweet.

    I would send it to George just for a check.
    Will put your mind at ease as well.

    Lol yeah these amps have quite a bit of gain. However when dimmed they have a different type of gain which has compression from the output section and sustain.
    Awesome amps.
     
  18. Tylenol Jones

    Tylenol Jones Member

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    Tried everything at noon but there wasn't a huge difference.

    I haven't had much time to dismantle it and take clips and pics. I'll try to that tonight.
     
  19. tone?

    tone? Member

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    Remember it is a Marshall.

    Wasn't created for cleans really.
    I still would send it to George.
     
  20. JB6464

    JB6464 Member

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    For some players that 's the main reason they love the 12,000 plexi amp styles .
     

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