Somebody has to be the first, might as well be me.

Discussion in 'Marshall Amps' started by Drinkingdeath01, Aug 7, 2019.

  1. Drinkingdeath01

    Drinkingdeath01 Well-Known Member Gold Supporting Member

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    I want a SC20 with the Jose mod. Anybody up for the challenge?

    I know, how dare you mod a classic but why not ? They're cheap and still available if it goes south in a hurry. Its not like were modding a 40 year old JMP. I'll be the first one to put mine up if David's into giving it a shot. (Sorry bro, but I'm really hoping your into the idea)
    No worries if your not, I just really love what your doing.

    Pros and cons comments are very welcome.

    :headbanger::headbanger:
     
  2. MonstersOfTheMidway

    MonstersOfTheMidway Well-Known Member

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    I don't know if I'd call the SC20 a "classic amp" just yet, but I think it certainly has the potential to do be so in a few years.

    As far as modification goes: it's your gear, your money, your time, and your effort (if you're the one doing the modification and not a tech). Modify to your hearts content.
     
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  3. mickeydg5

    mickeydg5 Well-Known Member

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  4. Dogs of Doom

    Dogs of Doom Moderator Staff Member

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    do it. When I get around to getting an SV20, I'm gonna mod the f*ck out of it & turn it into a fire breathing dragon...
     
  5. 67Mopar

    67Mopar Well-Known Member

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    What would be cool, is if Marshall made a plexi circuit with swappable components. Then again, I suppose that would open the door to injury/fatality risk. Seymour Duncan made an amp that used modules, but I could never zero-in on a configuration that I liked.
     
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  6. mickeydg5

    mickeydg5 Well-Known Member

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    That is not far fetched.
    My idea is to build an amplifier with variables that matter along with the normal controls. You can dial in anything but limited to lets say a two channel amplifier. Who really needs more than a clean, a distortion and an effects loop for whatever?
     
  7. 67Mopar

    67Mopar Well-Known Member

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    I talked with Guy Hedrick about this very subject several years ago. By that time, I think he was burned-out on building amplifiers. He designed and build some amplifiers for Suhr, then disappeared again.
     
  8. ampmadscientist

    ampmadscientist Well-Known Member

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    The Duncan amp was a failure, the of the biggest fails in amp history.
     
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  9. 67Mopar

    67Mopar Well-Known Member

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    It was, but damn... I could get some great tone out of that amp; as long as it was cranked. I came up with my best lead break using that amp. That same night, the amp choked, popped, and went up in flames! The best leads are written at maximum volume.
     
  10. ampmadscientist

    ampmadscientist Well-Known Member

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    I hear that there is a whole room filled with amp modules that Seymour won't sell or even talk about to anybody.
    Yeah it was the capacitors shorting out that popped.
    The amp would go like 100 volts over the cap voltage when it was first turned on, then the voltage drops back down but not fast enough apparently.
     
  11. ampmadscientist

    ampmadscientist Well-Known Member

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    Why, do you have a schematic for SC20?
     
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  12. Drinkingdeath01

    Drinkingdeath01 Well-Known Member Gold Supporting Member

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    If I did I would post it for all of us to see.
     
  13. ampmadscientist

    ampmadscientist Well-Known Member

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    If there was schematic then I could design a mod, but since there is none you should draw one.
     
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  14. Drinkingdeath01

    Drinkingdeath01 Well-Known Member Gold Supporting Member

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  15. Fusedbrain

    Fusedbrain Active Member

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    YMMV, but this seems like a bad idea on a lot of levels.
    For less money than what these sell for you could buy a 50watt MV kit and build your modded 800 on a turret board and cherry pick your iron and caps etc...from the various sources available. Working on that SC20 pcb is going to be a nightmare. Oh yeah, you can customize your power supply and filtering scheme too.
    Which brings us to the second issue: the plate voltage.
    The SC20 runs on a way low plate voltage from a smallish power transformer ( and I think Cathode bias as well) to get 2x EL34's down to 20watts. Given the added compression and squish that comes with the "Jose diode thing" you really need some cranked up plate voltages to get the best out of these type of amps ( MC's CCV type amps are usually 500v plus on the plates )
    A "Jose" amp with 95 volts on the first triode plate is gonna sound like a bowl of mashed potatoes.

    What? You want the lower wattage. Well......you could go with an 18watt TMB kit, or use the 50 watt kit, but build it with 6V6's and the appropriate OPT, but then you are limited with your plate voltage again.
    I built an 18watt CCV clone for a buddy for recording in an apartment that sounds pretty good at lower vols ( what he wanted ) but it just doesn't cut and punch like the big boys when you crank it up in a band context.
    No free lunch here. Getting that amp to sound good with 380v DC comming out of the rectifier was a bitch.
    Power in = power out.
    The amp IS the power supply after all....

    Just seems like folly to me, but what the hell do I know......
     

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