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How-To: USA Big Muff to Colorsound Tone Bender conversion

Discussion in 'Effects [BG]' started by sonicvi, Aug 13, 2007.


  1. sonicvi

    sonicvi

    Jun 10, 2005
    Houston, TX
    Ok, since a few of you have expressed interest in this mod here's how it's done. Sorry the pcb pics aren't better. There are a few extra resistors on the BM board that should be left eventhough they aren't on the JTB schematic, the ones labeled pulldown and LED. They don't have any effect on sound. Also, the BM uses two power supply filter caps (C13) instead of the one in the Bender. This shouldn't really make much if any difference but you can change those if you want to as well. Lastly, I show that a trace should be cut. That's optional I don't think it matters. If you cut it and it doesn't sound right then reconnect it. EH was nice enough to put to empty holes right where that cap (C9) goes. I don't know why, maybe they anticipated us wnating to do this mod:). Other than that it should be straight forward. Remove all the parts labeled for removal and compare all the resistors with those in the schematic to find the ones that need to be changed. Small differences like 470pF vs 500pF or 470K vs 510K probably don't make much if any audible difference. Tolerances in components could make them be about the same in the end anyway. As far as using mylars for the .1 caps, that's just what the original Jumbo used. Use electrolytics or polystyrene or whatever you want. I forgot to label C10 and C11 on the pic, but they don't change anyway. Ok, that's it, feel free to ask me if you have any questions.
    [​IMG]
    [​IMG]
     
  2. BassJunkie730

    BassJunkie730

    Feb 3, 2005
    Brooklyn
    Thank you so much - I'm going to do this mod ASAP and I'll post my experiences. I've already modded my NYC big muff heavily - but I'm not satisfied with where it is right now.

    I'm looking for something a bit more jagged and low middy - and apparently this fits the bill.

    Thanks again!
     
  3. BassJunkie730

    BassJunkie730

    Feb 3, 2005
    Brooklyn
    here's a bill of Materials as they correspond to the values on the schem and the image of the Muff board

    Bill of materials

    Q1,2,3 - BC184C

    D1,2 - 1N4148

    R1 - 33K
    R2 - 470K
    R3 - 100K
    R5 - 100
    R6 - 1K
    R7 - 8K2
    R8 - 470K
    R9 - 100K
    R10 - 10K
    R11 - 100
    R12 - 8K2
    R13 - 470k
    R14 - 100K
    R15 - 15K
    R16 - 100
    R17 - 33K
    R18 - 33K

    c1,3,4,6,7,9,12 - 0.1mf
    C2,5,8 - 500pf
    C13 - 22mf (2)

    GET AN EXTRA .1mf FOR UNDERSIDE OF BOARD


    please check my list and make sure i got everything correct.

    Hope this helps.
     
  4. BassJunkie730

    BassJunkie730

    Feb 3, 2005
    Brooklyn
    Anybody have parts supplier suggestions other than Mouser?

    I checked small bear and evidently they do not sell the BC184C bipolar silicon transitors.

    ???
     
  5. sonicvi

    sonicvi

    Jun 10, 2005
    Houston, TX
    You might have trouble finding 500pf caps, in which case the stock 470pf caps are just fine.

    Mouser is the only place I checked for the transistors. I prefer using Mouser becasue they're in Texas and I usually get my parts in 1-2 days.

    Be sure to check the datasheet for the pinouts on the transistors, especially if you solder them in.

    Note that not all of the resistors need to be replaced. For example, R5 is already 100 ohms. I think you need to add R4 as well. It's the one next to R7 that isn't labeled.
     
  6. BassJunkie730

    BassJunkie730

    Feb 3, 2005
    Brooklyn
    I spec'd out about $12 in parts from Small Bear electronics minus shipping and the BC184C transistors
     
  7. sonicvi

    sonicvi

    Jun 10, 2005
    Houston, TX
    It'd probably be about $3-4 plus postage from Mouser.
     
  8. BassJunkie730

    BassJunkie730

    Feb 3, 2005
    Brooklyn
    +1 good to know!
     
  9. sonicvi

    sonicvi

    Jun 10, 2005
    Houston, TX
    well, actually, that's a lie, I forgot you have to order a minimum of 10 of each value of resistors at 9 cents a piece I think. So that's like $7 for resistors, making it more like $10. And I always order at least one extra of everything in case I break a lead or burn it or lose it or solder it backwards or whatever.
     
  10. Just curious, what's the pinouts of most BC184C's? Is the pinout different from a 2n5088?

    Thanks,

    Lyle
     
  11. sonicvi

    sonicvi

    Jun 10, 2005
    Houston, TX
    It can vary from manufacturer to manufacturer. That's why you need to check the manufacturer's data sheet. 2N5088's from two different makers can have different pinouts. I think the only BC184C's that Mouser has are from Fairchild.
     
  12. :rolleyes: ...well I checked the orientation of my transistors, and found out that I had them in wrong. The Fairchild BC184C's are CBE (when looking at the flat face), where as some other transistors are EBC. My PCB was orientated to EBC. I should have known something was up, as it sounded okay but didn't quite have the gain or volume that I expected. It sounds much better now, with more volume and fuzz.

    Just a heads up to anyone doing this mod or building a Jumbo clone.

    Lyle
     
  13. BassJunkie730

    BassJunkie730

    Feb 3, 2005
    Brooklyn
    so mouser is backordered on BC184C transistors until december of this year.

    anybody want to sell me some stock?
     
  14. Did you try Digikey? I ordered mine from them and they seemed to have lots of stock. Digikey sells the Fairchild type.

    Lyle
     
  15. Sir Edward V

    Sir Edward V Not Actually Knighted... Yet!

    Dec 11, 2006
    Massachusetts
    is the tonebender supposed to be so similar to a big muff or is this just a coincidence?
     
  16. sonicvi

    sonicvi

    Jun 10, 2005
    Houston, TX
    The Big Muff was around first so you have to thnk the JTB is derivative of it. The Supa Tone Bender is even closer.
     
  17. BassJunkie730

    BassJunkie730

    Feb 3, 2005
    Brooklyn
    So I just ordered from Mouser and Digikey

    the transistors from digikey and the rest from the mouse.

    I doubled the quantities of pretty much everything to allow for error.

    I also ordered a DOD 250 in hopes that I can increase the bass response using some of the extra .1uf caps.

    I should end up with some kicking OD/Dist/Fuzz tone

    I'll keep everyone here posted.

    If all goes according to plan I'll have clips on sunday.
     
  18. BassJunkie730

    BassJunkie730

    Feb 3, 2005
    Brooklyn
    Got the parts today. I'll be soldering up a storm tonight I suspect.

    Just a note - I ordered mica 500pf caps and they are HUGE! I think i'm going to have to solder them on the underside of the board. Oh well I'll make it work.

    Now I just need a some desoldering braid - Radioshack here I come.
     
  19. sonicvi

    sonicvi

    Jun 10, 2005
    Houston, TX
    Pick up a heat sink for the transistors as well if you don't have one, or else socket them.

    Exactly how big are these caps?
    I have big blue ones in mine. Cause of course blue sounds better :)
    [​IMG]
     
  20. BassJunkie730

    BassJunkie730

    Feb 3, 2005
    Brooklyn
    They are about that size.

    Is that board an actual tonebender? - because it looks nothing like the NYC Big Muff board.

    No worries about the socketing - I solder very fast and tweezers are your best friend when it comes to a heat sink :cool:
     

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