OD-2R low pass filter / Bass increase? help please!

Discussion in 'The Stomp Box' started by telepath, Aug 22, 2012.

  1. telepath

    telepath Friend of Leo's

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    Hi,

    I have posted a similar question on a stomp-box forum, but thought I'd ask here also.

    I have a Boss OD-2 ('turbo' OD) - MIJ.
    The non footswithchable older model.
    I really like it. Quite different to most other Boss OD's

    I was able to usefully mod it easily by putting a SPDT to toggle the C35 cap between stock (.18uF) and a .22uF

    Works a treat for a little bit more low-end if required, and no vol loss nor change of tonal characteristic when engaged

    I got the idea from an ancient post I found by Brian Wampler from back in his IndyGuitarist days



    Happy with my mod, I then also managed to snag a OD-2R - MIT , the later one with the remote switch.
    It is louder (good!) but aside from that it sounds very, very similar.
    However the circuit is apparently completely different :eek:

    I'd really hoped I could do the same , simple 'one cap' mod to the OD-2R

    Ok I'm waffling:

    My request is - does anyone have any good info on lowering the low-pass / bass cut on an OD-2R MIT please?

    or

    Could anyone with a good eye tell me which cap is the OD-2 'C35' equivalent on an OD-2R maybe? I tried, but that is beyond my skills!

    Schematics for both - attached.
    On the OD-2 MIJ schematic 'C35' is the .18uF up there in the top right

    Any help much appreciated!

    edit: sorry - those attached schematics dont seem to enlarge too well as attachments here. I can try uploading them somewhere maybe.
     

    Attached Files:

  2. cousinpaul

    cousinpaul Friend of Leo's

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    According to Mr.Wampler's book, increase C12 to add bass to the turbo channel; increase C17 to add bass to the normal channel. He recommends .22uf for both but that's such a big change from the stock .018uf I suspect it could be a typo. You might PM him about that.
     
  3. telepath

    telepath Friend of Leo's

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    CousinPaul, you are a star! Thank you!

    That adds up nice. I see now on the MIT schem that C12 and C17 are both .18uF and the change you advise that B.W. suggests is to a .22uF, so it is not actually that big a change up - and in fact it is the same value changes exactly as the one change (C35) on the simpler circuit OD-2 MIJ.
    (and which worked out really well)


    I just needed to know which caps to change in the MIT, as there were a few potential candidates on the board there to my amateur eye - and you came up trumps.

    Very much appreciated.
     
  4. cousinpaul

    cousinpaul Friend of Leo's

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    All I did was look it up in Brian's book. According to the book, the stock value of both caps is .018uf, not .18uf so it really is a pretty big change. Let us know how the mod works out.
     
  5. telepath

    telepath Friend of Leo's

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    Cheers - will do.
    Schematic shows .18uF for the two caps you mention, so I think that .018 may be a typo .

    Previous (successful) mod to an OD-2 MIJ was to swap an .18uF (C35) to a .22uF, so at this point, I'm relatively confident.

    I have some .22's in the post - then I will crack it open, give it a go and report back.
     
  6. telepath

    telepath Friend of Leo's

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    Thanks, that mod worked out great. OD and Turbo mode now have a bit more girth and low end.
    Cheers
     
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