How do I allow two signal inputs on one pedal?

[fingersoccer]

I want to be able to have two inputs for a delay pedal I'm building. So, for instance, I could plug in a guitar and a synth at the same time and play through the pedal.
Is this a simple matter of having two 1/4" jacks and connecting both tips to the input of the board, or will it be something more complicated?

Thanks.

[PRR]

> a guitar and a synth

Synth is usually much stronger: both higher voltage and lower impedance.

> connecting both tips to the input

That causes a "fight" and the synth will usually win.

You "can" mix two similar guitars that way. However this is better with a couple of 68K resistors so the two guitars don't "fight" each other.

In general for two dis-similar sources, you want some form of mixer and possibly with level controls. This could be as simple as two pots and two 47K-100K resistors. (Maybe one pot if one of the two inputs is never "too strong", which is probably the case here.)

[Paul Marossy]

This might help you get what you want: http://www.runoffgroove.com/splitter-blend.html

[fingersoccer]

OK, what if the guitar signal was boosted before it was mixed in with the synth?
To be more specific: I'm building a multi-effects unit for guitar and think it would be cool to add a simple drum synth in there somewhere that I can play along to (http://www.paia.com/proddetail.asp?prod=9302K). If the guitar signal goes through a pedal first, won't it effectively be at 'line-level' and be able to compete with the drum synth (especially if I turn down the volume on the drums)?

[Paul Marossy]

OK, what if the guitar signal was boosted before it was mixed in with the synth?
To be more specific: I'm building a multi-effects unit for guitar and think it would be cool to add a simple drum synth in there somewhere that I can play along to (http://www.paia.com/proddetail.asp?prod=9302K). If the guitar signal goes through a pedal first, won't it effectively be at 'line-level' and be able to compete with the drum synth (especially if I turn down the volume on the drums)?

That might work. But you may also have some input/output impedance issues come into play.

[goulashnakov]

This might work for you:

http://www.montagar.com/~patj/smixer.gif

That's about as simple a mixer as I've seen, and it looks like it could suit the needs you describe.