CMATMODS Brownie question...

Discussion in 'Effects, Pedals, Strings & Things' started by Pavel, Aug 3, 2008.

  1. Pavel

    Pavel Member

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    Got the Brownie recently; awesome pedal! I do wish it had a bit more hair/presence to it. I read that some folks have achieved this by clipping out certain component(s) to make it brighter.

    Below is a shot of the circuit board. What did you remove to make the pedal brighter?

    Also, what is the function of the trim pot?

    [​IMG]

    [​IMG]
     
    Last edited: Aug 3, 2008
  2. Cary Chilton

    Cary Chilton Senior Member

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  3. Ohzoso

    Ohzoso Member

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    Just roll back your axe`s volumeknob somewhere halfway and there comes the brightness. Then set the gain a tad higher if you need more. Great pedal.
     
  4. Cary Chilton

    Cary Chilton Senior Member

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    wow! Great news for me.... I don't think we could have tried that first???
    :jo:jo:jo:jo
    :jo:jo:jo:jo
     
  5. steelplayer

    steelplayer Member

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    To make the pedal overall brighter, one could try replacing the input and output capacitors with lower values.

    If I remember correctly, the trimpot in this circuit adjusts transistor drain voltage.

    Hey, drop Chad Mathews at Cmatmods an email. He's a super nice guy and I'm sure he'd help you with all the information you need to tune your pedal to your liking.

    best,
    LarryW
     
  6. recto-robbie

    recto-robbie Member

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    +1000 on that one,, highly suggest doing what Larry said,, Chad Mathews is an excellent person to deal with. All good.
     
  7. rpjones

    rpjones Member

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    the two .0022uf caps to ground right before the volume pot connection. They simulate the speaker rolloff of a 4x12 cab. If you clip them the sound will be more open. You might want to try clipping one of them first (either one) and see how that sounds to you, if you need more highs just clip the other one.
     
  8. Unabender

    Unabender Member

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    Is this the one based on BSIAB2? If it is, the trim pot probably is a set-and-forget kind of voltage divider for the last transistor to operate, if I remember correctly. It's not on the signal path.
     
  9. nibus

    nibus Supporting Member

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    Could you possible post a picture pointing out these caps? i'm an electronics dummy and don't want to render my Brownie unusable.
     
  10. Pavel

    Pavel Member

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    Here's the same photo with the caps (or what I think are caps, haha) labeled. Which are the two that roll off the highs? My guess would be 11 and 12.

    [​IMG]
     
  11. Bucksears

    Bucksears Silver Supporting Member

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    My guess would be 10 and 12; just look for the two that read .0022 on the board, nearest to the volume/out connection.
    I suggested clipping these two caps some time ago at diystompboxes.com. It increases the brightness greatly, but still allows you to darken it up as you roll back the tone control.

    One config I'm loving right now is using just one .001uF cap in the low pass filter (the two caps we're talking about). I'm gonna have to make some clips of that one day; classic rock/Marshall sound, but not 100% early VH. Leave the two .0022uF caps out for that.
     
  12. Pavel

    Pavel Member

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    You're correct!

    I emailed Chad as few people suggested (he got back to me in 1/2 hour... awesome!), and 10 and 12 are the low-pass filter caps.

    :dude
     
  13. nibus

    nibus Supporting Member

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    So do you just cut each of those connections with a wire clipper or what?
     
  14. Pavel

    Pavel Member

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    To remove them permanently, yes. Just clip them out... if you go this route, I'd remove one of them first, see how you like the sound, and if you want it even brighter then clip the 2nd.

    To make the mod easily reversible (requires soldering), here's what Chad suggested: "If you are good with a soldering iron you may try lifting one side of each and see how that works for you. To remove the circuit board just take the knobs off and take the pot nuts loose, pop the LED out and it will come right out. If you don't like the mod then you can solder them back".
     
  15. nibus

    nibus Supporting Member

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    Cool, I'll try the soldering trick so I can reverse it if necessary.

    IMO if the Brownie had more pleasing / soft highs it would be the ultimate Marshall in a box.
     
  16. Axekisser

    Axekisser Member

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    Ok I'll ask.. what's up with cap "2" hanging off the board like that? It ain't like that on my BSIAB II! BTW, by removing one cap (10 or 12) my pedal really opened up. Great sparkly boost pedal now! I also lowered the gain on mine and it's perfect now!
     
  17. Pavel

    Pavel Member

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    I'm not sure. I'm guessing that due to it's proximity to cap "3" it just cannot stick up straight. I haven't seen the BSIAB II board, but the Brownie board is quite small.
     
  18. Bucksears

    Bucksears Silver Supporting Member

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    If possible, I'd socket those two capacitors so you can mix/match/remove as you like.
     
  19. Pavel

    Pavel Member

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    That's a good idea!
     
  20. nibus

    nibus Supporting Member

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    Any links to parts for socketing? I've never done it.
     

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