summing box (to sum delay trails with dry signal to get spillover)

[el_camello]

i'm trying to make a summing box like this thing used in reverse http://www.loop-master.com/product_info.php?products_id=225

What i want to do:
My guitar goes into an A/B selector. I can switch between going dry or to a delay. The output of the delay and my dry signal get summed up. If i switch out of the delay chain it still outputs over my now dry signal so i get the spillover trails. problem is that when i hook up the summing my dry signal doesn't come through, only my delay chain does. when i disconnect my delay chain then my dry signal works. for the three jacks in the summing box i just connected all the tips and all the sleeves. i guess it's more complicated than that... any one know what to do? i found this http://www.rane.com/note109.html but it confused me with the 3 terminal jacks considering i'm using mono guitar cables. is there a simple schematic out there?

here is a diagram:
A->Delay->SummingBoxInput1
B->------->SummingBoxInput2

[slacker]

If you're trying to do this just with jacks it won't work. Referring to your diagram, what happens is you're connecting B to the output of the delay, this is low impedance, so it's basically like connecting your dry signal to ground, which is why you can't hear it.
You need to use resistors to do the mixing like this

Summing box input 1-----Resistor-----\_____Out
Summing box input 2-----Resistor-----/

Something like 1k to 10k would work for the resistors. You'll need to put a buffer in front of the A/B box though, or a pedal that has a buffer otherwise you'll get tone sucking in the dry setting.

There's a simple circuit that takes care of everything here http://www.diystompboxes.com/smfforum/index.php?topic=90340.0

[el_camello]

thanks! it works with the resistors.

what do the resistor values change? if i experiment with different values what will be different? if it'll change something i'm considering putting trimpots in my pedal and tweaking on the go.

[el_camello]

hrm, definetly alittle tone sucking even with a buffered pedal infront, is there something to help that without going using a battery?

EDIT: i played around with the values, from what i can tell either the dry chain will get tone sucked or the delay chain will get tone sucked. i guess that's what the circuit you posted fixes?

thanks!