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.


  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.

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

  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.

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

      Thanks man!

  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:



  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.

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