Stereo ABY Help?

[justoneghost]

Hello!

so i am pretty new to making pedals (my first design). i'm not sure if it will work and i don't wanna kill my pedals ha. its supposed to be a stereo in-out/ mono LR select. for the L/R selection switch i combined the left and right channel to be sent to either left or right. the part i am unsure of, is the combining the L and R from a stereo pedal back into a mono signal. i guess i thought that combining the signals would act as kind of a volume boost. i envisioned using this pedal last in my pedal set-up, which is a volume--->wah--->POG--->mod blues driver--->OCD--->memoryman stereo-out--->stereo-in boss dd-7 (used for loops)--->stereo-out.  i figured i wanna be able to have the choice of two amps in stereo for clean/od/stereo delay/loop or mono LR toggle for mono clean/od/delay/loop. i would be cool if combining the stereo into a mono would give it a boost even if its a small one. however, killing my pedals would suck. another option is to keep the LR toggle just one or the other. my concern with that is the signal being lower in one of them.  i also though i could just use the left signal to be sent L or R out, but again i dont want it to be quieter than when it was in stereo. this is a link to the schematic i came up with. i would post the pic here but i dont know how... like i said im new to this so please let me know what you think. is it self destructive?

http://www.mediafire.com/i/?7big0ultixc3sw2

Cheers,
Ryan

[justoneghost]

also does anyone have any suggestion for adding a third switch to control a treble volume boost with mini pots inside the pedal to be "biased"? one for the volume, one for the treble.

[familyortiz]

Your design will probably draw from many sources given the options you want, but here is the link to a schematic of mine that will do the summing of the stereo to mono. It also has a gain stage that allows gains from 0.1 to 2.1x. You can forget the input switches... you could have a stereo jack on your pedal and either input your stereo plug or a mono plug with no issues since it does not matter if one of the input legs of the summing junction is left open. This design is for split supplies (+/- 9v or other) if you're operating from a single supply (+9v or other) you need to bias the opamp to a pseudo ground. Feel free to reply with questions or comments. I know the bias/supply thing seems heavy but you will be learning all kinds of stuff by the time your done. cheers.

http://www.aronnelson.com/gallery/main.php/v/familyortiz/2CH+COMBINER+STAGE+WITH+ADJ+GAIN.JPG.html?g2_imageViewsIndex=1

[familyortiz]

BTW, I checked your switch schematic. There are many reasons to design this with a powered circuit, none of which is that complex. For the case of summing the outputs of a pedal, I would not want the L/R outputs wrestling with each other without isolation or sending 2 signals to the amps without transformer isolation of at least one of the channels. Lots of A/B/Y info to search on here. In either case, you got a great idea going on there for what you want.

[digi2t]

also does anyone have any suggestion for adding a third switch to control a treble volume boost with mini pots inside the pedal to be "biased"? one for the volume, one for the treble.

Why not just build a stereo Omega in a separate box? http://www.runoffgroove.com/omega.html Then you could use it anywhere, anytime on it's own. Then you could use a stereo ABY switching configuration to either boost one side or the other, or both. Omega is a great design, and a stereo design will allow you to treble boost one side, and full range boost the other. And, you won't have to mess with your pedals.

Cheers,
Dino

[justoneghost]

thanks for all the info. i am thinking i am gonna try your stereo in boost in there. there is so much out there on this topic haha. does anything change if i wanna make the pedal powered from a transformer? on another note. i have been wanting to put leds on my reverb/ trem pedal for my SF deluxe reverb and my gibson rvt-15. any ideas besides adding a batt powered led the get switched at the same time? also i could totally use some kind of schematic cheat sheet to learn symbols if you have any suggestions.