How to wire two effects in parallel inside the box?

grrrunge · Post by **grrrunge** » 26 Jul 2011, 14:00

The bass player from one of my bands and i tried out some different distortions/overdrives for his bass the other day. He ended up being madly in love with the sound of my modded BOSS SD-1 in parallel with a EHX Linear Power Boost. We talked about building a pedal for him, and i suppose that would be pretty cheap and easy, as musikding carries pcb's for both the SD-1 and the LPB.

I imagine a box with content as follows:

buffer pcb: http://www.musikding.de/product_info.ph ... r-kit.html
LPB pcb: http://www.musikding.de/product_info.ph ... r-kit.html
SD-1 pcb: http://www.musikding.de/product_info.ph ... e-kit.html

input -> buffer pcb -> SD-1 and LPB in parallel -> output

My questions are:
1: Can i just wire the output from the two pcb's together at the output jack?
2: Is the input buffer overkill? I just thought it's a nice thing to have

Thanks in advance,
/grrrunge

reneshelle · Post by **reneshelle** » 26 Jul 2011, 14:43

How did you do it with the actual pedals? You could do it the same way inside the box, unless you used something like a boss ls-2 to blend them.

But is it not more or less a modded tubescreamer/sd-1 with a clean blend pot you're after? Might be easier to do that with only one board...

I don't know if it's overkill with the input-buffer, but if you're doing the sd-1+lpb1 thing then perhaps some sort of mixingstage at the output? But I don't know if you really need it.

grrrunge · Post by **grrrunge** » 26 Jul 2011, 15:26

We talked about some sort of blend knob, but agreed that both pedals have a volume knob already, so used in conjunction they act like some sort of mixer stage already.

We tested the bass through an off metal zone for the buffer, y cable into LPB and SD-1 and then their respective outputs into a DOD 240 passive mixer as we didn't have more y cables...

reneshelle · Post by **reneshelle** » 26 Jul 2011, 16:22

If you used a DOD 240 you're already "wiring" the two outputs together. As far as I remember the 240 is totally pasive, meaning no buffers and just volume controls going to ground. So it seems fine to just connect the outputs.

As far as the input buffer go. It's not much of a problem installing it, and you could make it always on and just true bypassing the two effects if you wished. Might be nice if your friend uses pasive bass guitars...

If you skip the buffer the "two" inputs will load the signal more than if it's just one. But that might not be a problem at all for him, especially if he uses active electronics in the instruments...

Nocentelli · Post by **Nocentelli** » 26 Jul 2011, 17:08

grrrunge wrote:We tested the bass through an off metal zone for the buffer, y cable into LPB and SD-1 and then their respective outputs into a DOD 240 passive mixer as we didn't have more y cables...

i'm similarly interested in this kind of scheme, as i'm planning a parallel trem+vibrato. from what i've read, some sort of input buffer/splitter circuit will do the trick, and you might get away with a simple passive mixer pot on the output, particularly if both circuits have an output level pot. i'd be inclined to make both boards, hook up the bass into the amz buffer/splitter muamp jobby, send two parallel output signals to the two boards, and wire the outputs of the two boards to lugs 1+3 of a linear pot, with lug 2 as the outpu: i'm guessing you could even just replicate this pot set at 50% with two 50k resistors on the ends of each output, and tie them as the output, as you said, the two volume controls should allow you to balance them. If there is any weird interaction, you might need to investigate an output mixer/buffer bloc.

frequencycentral · Post by **frequencycentral** » 26 Jul 2011, 17:36

If I was doing this I'd buffer the hell out of it. IMO an output bufer is essential or there is going to be interaction. I'd probably adapt something like the Bblender to do the job - two of everything, 5 opamps.