DOD FX25 Envelope Filter

[YerayM]

First of all I would like to thanks Mark and Miro for their work. I have built 8 pedals now, all of them with their layouts. This is my way of giving  something back to the community they are helping to create.

The DOD FX25 is a good sounding envelope filter. It uses an OTA State Variable Filter like the Snow White but with a much simpler enevelope detector section.

It's my first vero that I think is worth sharing. I've given it quite some time and several iterations but I couldn't avoid some standing resistors without making the board bigger. At least this can be mounted in a 1590b,  althought I would recommend a 125b.



I used the schematic by Alex Petrini (http://topopiccione.atspace.com/PJ11DODfx25.html) and added some mods suggested by Mark Hammer at DIYSB. One is the filter mode selector switch to select between band pass mode like the original unit or low pass mode which is good for bass players (just take the output from pin 8 or 9 of the LM13600 before C11). The other is the decay pot which puts resistance to ground in parallel with C7 to help it discharge faster (R24 and decay pot). The cap values to improve bass response were also suggested in a DIYSB thread.

I have built mine with a 4558 opamp for IC1, LM13700 for IC2 and bass cap values for C4, C9 and C10.





I would like to see the Mark or Miro version of this because I think I could learn a couple of tricks ;).

[Ciaran Haslett]

Easing myself back into building after quite a break from it and started with this.  Great sounding, simple autowah.  Genuinely prefer it to my SWAW if only for its simplicity.  Wasn't really happy with the bandpass/low pass switch so I wired the board for bandpass like the original.  Thank you Yeray (3+ years later)

YerayM wrote

I would like to see the Mark or Miro version of this because I think I could learn a couple of tricks ;).

....or Alex...or Zach...or Travis  The layout could definitely benefit from more "conventional" design rules.