DOD fx25 replica ground wiring question

[Oz]

Hi there

there seem to be a few posts re this pedal project, but none that address my questions. I'm keen to build one to give to a bassist friend of mine based on the layout here: http://topopiccione.atspace.com/PJ11DODfx25.html

My depth of knowledge is limited, but shouldn't there be at least one pad on the PCB to connect the ground to?the batt/PSU would have to be connected(surely...), and even if the in/out jacks are earthed together by the case, shouldn't they too be connected to the circuit? If not, can anyone please explain so that I understand why for future reference.

Also, I'm not sure I understand the pot wiring. What does "a" and "bc" refer to? does p1 just bleed to ground? what about p2?

Please look at the pcb layout in the above link.

Finally, apparently the newer versions added a "blend" control to blend in the clean signal. Is this a straightforward mod? how do you add a blend control? could it be added to any pedal? (like the "effect level" on many boss pedals?)


Great forums and thanks in advance for any (much needed) responses.

- Oscar

[Oz]

Ok I found a blender circuit which I assume will work on any pedal...(?) (for anyone else looking for the same ...http://www.seanm.ca/stomp/minblend.html )

Any comments/answers on the ground and pot wiring still much appreciated... thanks

[Mark Hammer]

The simplest blend for this circuit is to run a second 1uf/1k pair from the output of IC1b (pin 7) to the junction of R21/R22.  That parallel output from the initial input stage will be at unity gain, yet mixed in using the same mixer resistor value as the filter signal (R21).  As such, it might not make the non-filter signal seem painfully obvious, especially when resonance is increased.  But it will make it more bass-friendly for very little investment.  Depending on the chassis and the rest of your packaging, this little mod may be as simple as running the cap and extra resistor from the pin 6/7 pads on the copper side to the pad for R21.  Make sure to avoid the leads touching anything they shouldn't.  A little slip of paper between the components and PCB after soldering should help avoid any mishaps.  Once you've tried that mod, we can take it from there, but that's the simplest, least invasive way to do what you want.

[Oz]

Thanks for your response Mark, I've actually read a couple of your previous posts re this circuit as well as the comments summed up on the topoppiccione site, and am intending to do several of the mods proposed, inc the switchable bandpass/lowpass and out put control..... Ill let you know how I get on.


Cheers!

PS thanks for the schematic i get the pot wiring now.