Friday, 25 January 2013

DOD FX50 Overdrive Preamp

Here's DOD's step up from OD250 - from around '82.

On the original unit, the chip used is TL022, which is low power dual opamp - But the other half doesn't touch the effect side at all - It's only used as a buffer for the bypassed signal. So i made the layout to house a single opamp instead. TL061 is low power single opamp from the same family of chips - so i believe it should sound pretty close to the original.




7 comments:

  1. I´m building this and noticed that D4 in this one and also in the FX55 should be reversed. I'll be back with news about both, since there are just 3 changes between the layouts.

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  2. The gain pot is reversed, changed that and it works just fine, and it sounds great! So, you can tag it :)

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  3. Sorry, i didn´t mean reversed, gain 2 is ok, gain 1 should be connected to the 3rd lug of the pot, not the 1st.

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    Replies
    1. Great. I'll update the layout with both fixes - and also the 55 layout too.

      Thanks man!
      +m

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  4. I built this one the other day and I love it. I also added a tone pot so I could tame the top end if I want to. thanks for posting it:

    pic:

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DOD/FX50.1-01.jpg

    internals:

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DOD/FX50.1-02.jpg

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  5. BTW, I found the schematic for the FX91 bass overdrive so I made one of those as well. I forgot how good thse DOD pedals were! I also added an additional clipper switch (two 3mm red leds) to it.

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DOD/BASSOD-01.jpg

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/DOD/BASSOD-02.jpg

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  6. Wow. This low part count job sounds pretty darn good. Very pleased with this one. This will get boxed for sure. Thanks

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