1983 JCM 800 2204...options for effects loop needed...

Discussion in 'The Workbench' started by Nev, Nov 19, 2020.

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  1. Nev

    Nev Member

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    I picked up what I thought was a dead JCM 800 2204 for a great price. I was told it was dead, and had a bad OT. Never turned it on, and bought it not knowing what it would cost to fix. I wanted to get it working and since it may need a new OT, and perhaps other things, I didn't feel bad about drilling holes into what would be a non original JCM 800 for an effects loop. I would keep it and use it, and I prefer a loop for effects.
    I get the amp back from the local repair and he says the OT is ok and that it was a few other small things instead and got it working again.
    So now, I still would like an effects loop but don't wanna drill holes. I looked at the Metropoulos Zero loss loop but it looks like holes need to be made unless there are other ways.
    I looked up using a speaker out to an attenuator, then line out from that going into my effects, out of the effects into a power amp, out of the power amp to a cab or two...this I learned is what is called the Wet/Dry/Wet set up.
    So need advice...
    Add the loop someway without drilling? If yes, how did you do it?
    Go W/D/W tell me what you used as the attenuator to have best results. Attenuators range in price so don't want to get crazy.
    Thanks!
     
  2. pedecamp

    pedecamp Well-Known Member

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    I was gonna recommend the Bad Cat Unleash but they dont seem to be available any more, maybe theres something else out there similar, its an external box between the amp and speaker that has an effects loop.
     
  3. RCM 800

    RCM 800 Well-Known Member

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    I just pump everything in the front of my 2204. Sounds fine to me. Maybe run the leads out of the top of the amp and make a bracket to attach to the back mesh? Then you would only add holes to the top of the chassis.
     
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  4. J5684

    J5684 Active Member

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    line out through an attenuator is not the same, you'll just have a attenuated dirty signal. The only hope would be to remote install the send/receive jacks with some kind of flat ribbon cable you can get to fit and run them to something you can attach them to. You'll have to be creative for sure.

    Wet/Dry/Wet usually is run with an a/b/Y switch or similar where you split the guitar signal on into a dry/overdrive amp and one, or two into a wet/clean amp with the FXs-reverb delay etc. I've seen similar situations using an attenuator for a line out is generally a clean amp that has no DI or FX loop, run that into the attenuator then line out an effects board or whatever then to a power amp. Look at WSP Jimmy Herring's set up, his is similar.

    No other way around it, if you want a true FX loop, you have to install some type of loop and it will require in/out jacks.
     
  5. South Park

    South Park Well-Known Member

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    The 2204 has two inputs you can jump the low input take out the jack and run the wires to the FX jacks and have one input .
     
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  6. pedecamp

    pedecamp Well-Known Member

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    Great idea! Build an external effects loop and plug it into the second speaker jack on the back, I might try to figure this out with mine! :yesway:
     
  7. StingRay85

    StingRay85 Well-Known Member

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    Just drill two holes in the back
     
  8. South Park

    South Park Well-Known Member

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    You only use the high input anyway . It is a sin to drill holes in vintage amp you can mod the amp and return it to stock specs some day if you want . I never got into FX loops until I built my soldano clone
     
  9. houseofrock

    houseofrock Well-Known Member

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    If you go w/d this will help. A small secondary amp will do. Dry from one amp and effects from the other.
    https://davidbrayamps.com/lo1.html
    There is probably a way to mount an effects loop without drilling extra holes.
    You just have to be creative.
     
  10. Greg70

    Greg70 Member

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    Use the existing DI jack and repurpose one of your speaker outputs for your two holes.
     
  11. Greg70

    Greg70 Member

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    Here's how I did my 2203 effects loop. Unfortunately it never sounded good when using the loop. The sound was super thin, almost like an impedance mismatch. But it sounded so great when not using the loop that I never bothered to mess with it until recently. I did it 25 years ago and have lost the schematic that I used. The only cutting is a hole saw for the extra tube. This uses the DI jack and one speaker jack for the send and return.

    JCM8001.jpg JCM800.jpg
     
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  12. Fender

    Fender Active Member

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    an effect loop requires an in and out path...
    so the only way i see to not drill is to condemn one speaker out put and replace it with a TRS cliff and plug in two mono to 1 stereo TRS adapter, label them properly and you're good to go you can rewire a metropoulos loop to fit that if you know what you're doing.

    DO NOT LISTEN TO IMBECILES WHO THINK IT'S SMART TO REMOVE THE LO INPUT : You'll very likely quickly find yourself that using the loop may make you like the lo-input
    the lo-input is also the perfect pedal platform. removing the lo input is getting rid of a good half on that amp please don't do that.

    also you definitely CANNOT get a dry/wet configuration with only one amp, pure and simple (unless it's a stereo amp with stereo return loop), forget this idea or buy other power amps
     
  13. StingRay85

    StingRay85 Well-Known Member

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    Also, a bypass switch and level control is typically needed, so you need 4 holes actually
     
  14. Fender

    Fender Active Member

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    you can wire the cliff TRS in/out to be the bypass switch and on many loop board, the level pots are mounted on the pcb itself (inside, so you got to adjust them with open amp but no drill)
     

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