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Splitter/Mixer with A/B feedback loops for each channel and single/mixed output

So here is one of these things that I came up with these nights that I can't sleep.
I've never really explored A/B, A/B/Y guitar pedals but I thought it would be good to have something like that...
But... for what?
One time I was playing around with this EQD Organizer clone guitar synthetizer pedal I built, and found the delay setting like something completely useless, like, it's unplayable. You just play your guitar and the sound comes like a second later. No dry signal.
But then I had this idea of why not having it come AFTER something that actually makes a sound. The "how" was my Electro-Harmonix Pulsar tremolo, which has stereo output and it works even with the effect off, providing a stereo output for a splitted signal.
So what I did was to connect the guitar to the tremolo, then the guitar synth to one of the tremolo outputs and then to a clean amplifier, then some distortion to the second tremolo output and to a second clean amplifier.
Tweaking the controls a bit I managed to find some amazing sound. But this was left there.
Years later I was looking for the heaviest possible guitar sound without going non-sense. So I thought, there's a limit to what you can do with a guitar. But then if you add another guitar, you will have more. And you know, more is MORE.
So yeah, two amps are a good thing, you will sound enormous.
But then at some point, while wiring some cool circuit to a guitar (will post about this later, if I don't, remind me) I started thinking, yeah, I can not connect two pedal lines in parallel with one amp.
And there you go, I didn't only need a signal splitter, but also a mixer.
So I didn't want to use multiple pedals to do this and I decided to build something that would do both signal split, then two feedback loops, and then a mixer.
Of course, researching in the internet resulted that someone already did this long ago, and I found it on the good old Runoffgroove website HERE.
I also found out that these guys added a phase inversor switch which is useful for what I want to do.
Awesome... I jut need to gather the parts, find the time to do it.
But then one night I was thinking... What if... I go geeker and deeper and do something crazier.
What about having a switch that selects between two different feedback loops for each channel?
But then, maybe I'm playing with this thing, and then I don't want two channels mixed, but just one.

And there it all happened.


I posted this image in some forums and someone told me:
I would just breadboard it and never show this paper to the feds or they’ll take you for the next unabomber.

I tried explaining this idea to several friends, but only one of them understood it.
One of them told me, Ahhh... that's too geek man...
So yeah, good idea.

I had all the necessary parts for the circuit at home, except for a 4PDT switch. And not enough 1/4 mono jacks.
So, going through the Run-off-groove diagrams, copied here for the sake of just-in-case-preservation:



For this circuit you need:

And then for the modifications I've done:


I didn't have a B25k pot so I used one with B100k value.
So there we go...

Got a chinese protoboard and started soldering.


First I just soldered the components:



Another day, I printed the ROG schematic and started connecting the components:


Not my best soldering job but well.

Then added the cables:


And the ICs... forgot to do that once and was wondering what was wrong.


Then prepared some testing environment. I have this testing board with two 1/4 inch jacks to test guitar pedal builds with ground, input and output connected to the board. Connected one channel send/return together for clean tone, then soldered a 1/4 jack for the other send and another one for the corresponding return, the potentiometer, the switch and the DC jack, with the +9v to the circuit and the -9v to the testing board to have ground available for the 1/4 jacks.


Went to the music room and connected a distortion pedal in the feedback loop with the jacks. Then the middle lug of the pot to the output in the board. I grounded the 1/4 jacks and powered everything...


After connecting the guitar input/output reversed and moving a bit the connection to the pot middle lug (output) the thing worked. Here is some audio. I'm going from full distorted channel to full clean channel and some settings in the middle.