Stuck in a rut! Some advice needed

Discussion in 'Shock Brother's DIY Amps' started by Burchill147, Jul 11, 2020.

  1. Burchill147

    Burchill147 TDPRI Member

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    Hi all,
    Just looking for some advice regarding my amp set up.
    A couple of years ago I built a single ended 1w jcm800, but I also now acquired a few overdrive pedals and a looper which I find likes to be played after an overdrive pedal and in front of a clean amp rather than a dirty amp.

    So what I’m thinking if possible is to modify or just completely rebuild my old amp to include some switches that’ll allow me to change the cathode resistors on the first 3 stages to make a clean or less overdriven amp?
    So I can play with my pedals if I fancy but still also have the option to bang it back into jcm mode and try my best 80s rockstar impression

    my old amp had a few switches in for a slash style #34 mod which I’d be removing as I’ve found it’s just too bright.

    any advice is greatly appreciated and I’m also open to any other ideas.

    ps. Was thinking about a dsl1 because it got the emulated our for headphone practice aswell but I just love building stuff haha!!
     
    andrewRneumann and soundchaser59 like this.
  2. andrewRneumann

    andrewRneumann Tele-Meister

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    I've been embroiled in a boxing match with a test amp over here. I've got the cathode resistors on potentiometers so I can adjust them as I'm playing. My findings so far would indicate a better road to go may be trying to adjust the attenuation between stages, and not the cathode resistors. I'm sure others have good/better ideas too.

    Maybe those with more experience could poke holes in this idea, but I'm going to imagine something. How about starting with the attenuator between the 2nd and 3rd stage? You could possibly replace the lower leg of the attenuator with 2 resistors in series. If it was 470k, how about a 150k on top of a 330k? When you are in 80's mode, both resistors in action. You press a button and ground out the connection between the 150k and 330k. This would cut the signal voltage by about 50% if I estimate right. I'm assuming that the 3rd stage is the first to break into overdrive. I've never owned or worked on a JCM800, so take it with a grain of salt!

    Good luck!
     
  3. soundchaser59

    soundchaser59 Tele-Afflicted

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    If I had that little 1w amp and I really liked it so far, I would not mess with it. If I wanted the ability to play any type of tones at very low power I would get one of those old Vox AD30 Valvetronix amps that has the "power soak" knob on the back panel.

    It has some very convincing amp models, enough to entertain you for hours, days and weeks, so you don't need pedals. You can save two sounds plus have a third "face value" sound and switch among the three sounds (if you have the footswitch). If you put a decent Eminence speaker in it (the speaker is imo where they cut the biggest corner to keep the price down) the sounds are really improved quite a bit. And the power soak knob lets you run as much gain or drive in front as you like at any volume, even sub-bedroom volumes. I always ran the power soak full and used the Master knob to set room volume. But it's a surprisingly good sounding amp for maybe $100 bucks used mint.
     
  4. rangercaster

    rangercaster Poster Extraordinaire

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    Just buy a new amp ...


    It's simpler ...

    Less work ...

    Keep the old one, though ...
     
  5. Jesco

    Jesco TDPRI Member

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    Instead of messing with the cathode resistors, you could put one or two preamp cathode bypass caps on a switch. Taking a cathode bypass cap should give you a more pedal friendly amp.
     
  6. Burchill147

    Burchill147 TDPRI Member

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    Thanks for all the replies guys!
    Still can’t decide although I might start with switching the bypass caps and possibly the bright cap so any signal from the pedals don’t cause to much unwanted noise.

    Maybe even just build a little fender knockoff amp for the pedals because I said I just love to tinker and build haha!!
     
  7. andrewRneumann

    andrewRneumann Tele-Meister

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    Which stages are bypassed in the current configuration?
     
  8. printer2

    printer2 Poster Extraordinaire

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    [​IMG]
     
  9. Burchill147

    Burchill147 TDPRI Member

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    the 1st and 3rd are bypassed I left the cold clipper on its own
     
  10. Lowerleftcoast

    Lowerleftcoast Tele-Afflicted

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    Check out this thread. It takes out a section of the preamp.
    Quieting Down a Pignose G40V
    Discussion in 'Amp Tech Center'
     
  11. andrewRneumann

    andrewRneumann Tele-Meister

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    Have you tried unsoldering one end of that 3rd stage bypass cap just see if that’s a cleaner tone you can deal with? I think that’s where I would start. Have fun tinkering.
     
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