Dookie Mod help

Discussion in 'The Workbench' started by JM5010, Oct 15, 2019.

  1. JM5010

    JM5010 Member

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    Hi guys, i’ve been messing with my JCM 800 style amp and i’m pretty close to that Dookie sound.

    I really want that low end “chug” that's heard on “When I Come Around” by Green Day.

    1) I get close to that “chug” when I hit the standby switch...i don’t know...it’s like the bass response or gain is increased as the B+ cuts down. Should i drop the B+?

    2) Should i add 10k 3w voltage dropping resistors? This amp doesn’t have any.

    3) This amp has 22uf caps on the preamp STOCK, would it make a difference if i put in 50uf caps?

    Sorry for all the questions! Thanks.

    59D2CF90-7417-4500-B49D-276A46DD164A.png

    Here's how it sounds right now:
     
    Last edited: Oct 17, 2019
  2. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    Hold on a second, which amp are you starting with?
    Is there a schematic to this amp, can you post a link to the schematic?
    It's not really possible until you have more documentation to work from.
    To do any mods you should have some clear picture of what the original is...
     
  3. ricksdisconnected

    ricksdisconnected Well-Known Member

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    just buy the Dookie pedal and be done.
     
    matttornado and JM5010 like this.
  4. JM5010

    JM5010 Member

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    It is a peavey windsor.
    I have made the preamp more “JCM 800” ish, as well as the power amp and PI. It has a LTP PI and the FX loop is gone.
     
  5. JM5010

    JM5010 Member

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    I will upload my custom schematics. Would a sound clip help? I know that it may seem insane trying to mod a damn peavey. But the sound is 80% there...it’s just missing that low end chug or something.
     
  6. JM5010

    JM5010 Member

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    WinDookiePA.png
    WinPRE.png

    R2 on the input jack is 47k! Forgot to correct that.
    NFB resistor is 100k and is coming from the 4ohm output.
     
    Last edited: Oct 16, 2019
  7. South Park

    South Park Well-Known Member

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    To get that 2204 sound you need the same choke and filter caps.it is more than just a preamp circuit . Post the whole schematic will help a lot
     
  8. JM5010

    JM5010 Member

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    Do different size filter caps really make a difference? And what would a choke do? This amp doesn’t have one.
     
  9. South Park

    South Park Well-Known Member

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    the choke resist changes voltage the filters resist changes current .together you get power wave action
     
  10. JM5010

    JM5010 Member

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    Sounds like a plan.

    Anyway, here's how it currently sounds. I double tracked the guitars and that's it, no post editing or EQ was added. Excuse my **** playing and recording... and the noise...Now i know why i need a choke...or possibly better filtering

    Pre amp: 6
    Treble: 4
    Bass: 6
    Middle: 4 (it's at 6 on the other track)
    Pres: 4.5
     
  11. J Saw

    J Saw Well-Known Member

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    It sounds pretty close now imo :D
     
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  12. JM5010

    JM5010 Member

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    I think i need a choke. I’m going to install what was on 70’s JMP’s
     
  13. GIBSON67

    GIBSON67 Well-Known Member

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    What cab are you using? Could be the speakers.
     
  14. JM5010

    JM5010 Member

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    Using a 1x12 with a V30
     
  15. Joey Stockton

    Joey Stockton New Member

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    That tone sounds pretty close to me. Try a bigger cab with (2) G12H30 55hz
     

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