Wiring question for 3 boards in a single enclosure

Danbieranowski

Well-known member
Hey all, This is a pretty ridiculous pedal setup, but a friend of mine wants it, so I'm gonna try it!

It's 3 pedals in a single enclosure, an EQ (Zapper), a Fuzz (Russian Muff), and a Distortion (Rat).

When looking at it from above he wants it in this order: Left - Fuzz, Middle - EQ, Right - Distortion

The order that he wants the wiring to work:
Input to hit the EQ first.
Then from the EQ split to the fuzz and to the distortion separately.
Then fuzz to its own output (Fuzz Out).
Distortion to its own output (Dist Out).
Fuzz and Distortion outputs ALSO both get sent to a summed output (not running one into the other, but directly off the output of each to a summed out).

The goal for this is that he plays an SVT with two inputs. He normally runs separate pedals into each channel (fuzz into one, distortion into the other) then mixes to taste. This will allow him to consolidate his board, but it will also allow him to get the same kind of gnarly tone on amps with only a single input instead of two inputs.

From what I understand about mA ratings on these circuits, they are very low, so combining into a single 100mA line probably wouldn't be a problem (?).

Anyways, the difficult part is obviously the internal wiring. I put together this diagram and I was just hoping someone with a bigger brain than mine can take a peek and tell me if it's solid. As always, this forum rules and thank you!

Here's the layout:
Green wire - From input to in of EQ.
Yellow wires - Out of EQ into input of Rat and Muff.
Blue wire - out of Rat to Distortion out.
Pink wire - Out of Muff to Fuzz Out.
Orange Wires - Out of Muff and Rat to Summed out.
DC Board - Handles power for each circuit.
Grounds (black wires) - I have these wired kind of weird. I just assume that each 1/4" Jack needs to be connected to the ground from any one of the boards (not sure if I'm understanding this correctly and ALL boards need to ground to EACH in and out).

Anyways, please rip this apart if it doesn't make sense so I can try to work this out in my brain. Thanks a bunch!


Ryans Layout.jpg
 
I'm afraid you're going to need some active mixing or at the very least isolation resistors, otherwise you're going to get the summed signal on all three outputs. Also, you can daisy-chain your grounds or run them all to to the same spot; no need to provide multiple connections to any given circuit or jack. I'll have draw something up and post it in a minute.
 
Maybe something like this.
Thank you so much for this. Just to make sure I understand, the isolation resistors are to prevent the signal from traveling that particular direction? That’s what’ll keep the individual outputs functioning?
 
Thank you so much for this. Just to make sure I understand, the isolation resistors are to prevent the signal from traveling that particular direction? That’s what’ll keep the individual outputs functioning?
Yep. The signal will go straight from distortion or fuzz to its own out output, but each one has to go through a resistor to get to the summed output. That way, the fuzz would have to go through two resistors to get to the distortion output, and vice versa.

It's not perfect, but it's quick and easy. A better way to do it would be to run both resistors to the + input of an op amp with the same or 1/2 the value resistor in its feedback loop. Without the op amp, you'll get a volume drop on the S channel. You can decrease the value of the resistors if the volume drops too much, and increase them if you aren't getting enough isolation on the individual outs. Since you've got two signals combining there, dropping the volume a bit is probably a good thing.

Without the resistors, distortion connects directly to S and fuzz connects directly to S, meaning the two are directly connected together. Also worth noting that if you stomp one effect off, the summed output will be a blend of clean signal + the other effect. If you've got a ton of gain and output volume dialed up on the other pedal it might not be very noticeable, though.
 
Yep. The signal will go straight from distortion or fuzz to its own out output, but each one has to go through a resistor to get to the summed output. That way, the fuzz would have to go through two resistors to get to the distortion output, and vice versa.

It's not perfect, but it's quick and easy. A better way to do it would be to run both resistors to the + input of an op amp with the same or 1/2 the value resistor in its feedback loop. Without the op amp, you'll get a volume drop on the S channel. You can decrease the value of the resistors if the volume drops too much, and increase them if you aren't getting enough isolation on the individual outs. Since you've got two signals combining there, dropping the volume a bit is probably a good thing.

Without the resistors, distortion connects directly to S and fuzz connects directly to S, meaning the two are directly connected together. Also worth noting that if you stomp one effect off, the summed output will be a blend of clean signal + the other effect. If you've got a ton of gain and output volume dialed up on the other pedal it might not be very noticeable, though.

This is beautiful. Thank you. The basic idea is that pedals would be on all the time. His bass amp has two channels with two inputs that are always active, so he can run the distortion into one, and the fuzz into the other, and he can use the individual amp channel volumes to mix the two to taste. The problem with this is that he has to have 3 pedals to accommodate this, and if he ends up using a different amp with a single input it throws that all out the door. So by using this circuit, he could either run the distortion to one channel and the fuzz to a second channel, or he could use the summed channel to pass into an amp with a single input and mix the two effects to taste with their individual volume knobs on the pedal. I don't think a drop in volume is a problem for the summed output specifically because A) he could always turn the amp up, and B) it's a combo of both pedals so like you said, maybe the drop is acceptable just based on that.

I don't really know enough about HOW circuits work to fully grasp the op-amp idea. I like the idea of doing it "right", but the resistor option does seem easier and I can understand it better based on your explanation. At least I can build it out and test it and see how things shake out!
 
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