Mixing Stereo Outs from a Pedal Into Mono?

[zombiwoof]

I'd like to make a small box to mix the stereo outs from a couple of pedals I have to mono, with a pot to control the mix.  Is there a simple way to do this passively, or does it have to be an active circuit for some reason?  Anyone know of a layout or schematic for something like this?

This is for certain pedals where the two outputs are one effected output and one direct signal, I'd like to be able to mix them in variable proportions instead of just combining them.  I'm not even sure what kind of pot I'd need to accomplish this (blend pot? dual pot?).

Thanks for any help.

[Processaurus]

A 50K linear pot with the two outside lugs going to the effects outputs and the wiper going to the amp will work most of the time. 

It might not get totally wet, or dry, in that case you would want a common panning circuit like is explained at Geofex ("Panning for Fun").  Inthe simplest, passive circuit of that (pot and 4 resistors), that eats some signal, if that is a problem then you tack on an opamp based gain recovery stage, as in the article.

What happens when you bypass the pedal though?  It might be best to either make a true bypass box with the pedal to be blended in the loop, with two returns being mixed into one return, so the whole shebang is out when you bypass the looper.  Or drill a hole into the stereo pedal and mod it directly.  That would be my move.

[Mark Hammer]

Just note that some "stereo" pedals involve the combination of inverted and non-inverted wet signals with dry at each of the outputs.  Combining those to mono results in the wet being called.  This would not be the case if you are simply interested in pedals with discrete wet and dry outputs, but things like stereo phasers or choruses can pose a problem.

[zombiwoof]

Both of the pedals I'm considering using this with are Arion pedals, one is a stereo compressor, the other a stereo distortion.  On each there is a setting that sends the effected signal to one output and the straight unaffected signal to the other output.  With the comp, which sounds great but loses a bit of bass when the effect is on, I thought it would help bring in some bass with the unaffected signal mixed in, and also it would make it similar to certain boutique comps that have the capability to mix in straight signal with the compressed signal.  In the case of the distortion, which is one of the few stereo distortions I have seen (I'm sure there are others), I read that you can get some good sounds by mixing the two outputs, and I thought it would be beneficial to be able to vary the mix.  Both pedals have buffered bypass, and to tell the truth I haven't used them enough yet to notice how good the buffer is.  I might consider making it a true bypass box as Processaurus mentioned, with some version of the panning control included if I can brainstorm how to do that.  I assume the simplest version you talked about with the 50k linear pot will lose a bit of signal because of the pot, correct?  Does the value of the pot have any influence on the signal loss?.  How did you arrive at the 50k value?  Both of these pedals have level controls, so wouldn't I be able to make up for the loss by matching the level of the effect and the bypassed sound with those controls (if I build the TB loop version)?  I would think so.

I'll read the panning article at GEO, that's one I've missed before.

Thanks to both of you for your input, I'm going to think about this some more.  I want to make this thing as compact as I can, as to not add too much to my pedalboard to do it.

Al