# Stereo Mod for Unison Double Tracker (Pythagoras)



## Jovi Bon Kenobi (Sep 21, 2020)

Here's a fantastic mod to allow the Unison Double Tracker's output to split into two channels, one wet, one dry. You can sculpt adjustable space, time, and dimension between two amps, i.e. Strymon Deco, Keeley 30ms, etc... Or how about panning ping-pong slap back? Or detuned in one amp, clean in the other for Beautiful chorus effect! You _will_ need a stereo breakout cable for this to truly shine. Something like this Hosa YPP-117 1/4" TRS to Dual 1/4" TSF Stereo Breakout Cable.




This modification will also work on any Pythagoras based PCB effect but IMO is suited particularly well to the Unison Double Tracker.

This was posted in another thread but should be in this one. I've built 4 of these and finally this last one is for myself since I can't seem to hold on to them.

What you will need:
-1K resistor
-1uF capacitor (MLCC or Film)
-Stereo output jack
-Oh, and two amplifiers ?



Attach the 1uF cap and 1K resistor in series to pin 1 of IC1 (the square pad) with enough extra hook-up wire to reach the output jack. I like to add the mod to the under side and heat shrink it for added stability. In the photo above I populated the board leaving IC1 for last so I could add the mod in without it getting in the way while soldering the required components.

Here is the completed modification. The only purple wire is the lead running from pin 1 of IC1 under the board. It's attached to the Ring lug of a stereo jack.




I hope you give it a shot! It's my favorite PCB on the site with this mod.


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## Nostradoomus (Sep 21, 2020)

Damn, back out the gate SWINGIN! Nice one


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## daeg (Sep 22, 2020)

Nice. You've tapped the dry, post opamp buffer and routed it to the Ring of the TRS Output jack correct?

So what happens when you use a Mono plug? That's going to shunt the the dry path to ground isn't it?


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## p_wats (Sep 22, 2020)

This works on Octagon/Arachnid too, but you pull the signal from the TL074 (I believe pin 7, if I recall). It's a great trick!


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## smithcircuits (Sep 27, 2020)

So cool! Any idea if this can be done with organ donor? Would I do the mod on pin 1 of the IC1 in that case too?


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## Sasan (Oct 6, 2020)

p_wats said:


> This works on Octagon/Arachnid too, but you pull the signal from the TL074 (I believe pin 7, if I recall). It's a great trick!


Could anyone confirm this? Would love to Stereo up my arachnid!


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## p_wats (Oct 6, 2020)

Sasan said:


> Could anyone confirm this? Would love to Stereo up my arachnid!



For the newer Arachnid boards (with the rotary selector) it's pin 7 of the TL074. Works great on mine.


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## p_wats (Oct 6, 2020)

For the older Arachnid boards (without the rotary selector) it's pin 1 of IC1 (the first TL072). 



smithcircuits said:


> So cool! Any idea if this can be done with organ donor? Would I do the mod on pin 1 of the IC1 in that case too?



I haven't built an Organ Donor, but looking at the schematic it should also be pin 1 of IC1 (I believe we were chatting on Reddit--Welcome!).


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## smithcircuits (Oct 20, 2020)

Ok, so I did this mod on an organ donor, but with two separate mono jacks for wet/dry. I don't get any dry signal passing when the effect is disengaged. Is there a workaround for this? Does that not happen when using a single trs cable? Thanks!


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