Guitar Splitter Box

[cps]

Hi,

I'd like to try running some of my guitar fx in parallel. To do this I'm going to need a splitter and a mixer. Just wondering if there are any schematics available for things like this?

Cheers,

Chris

[Paul Marossy]

There's this schematic: http://www.geofex.com/FX_images/spltr2.gif
I think that could accomplish what you want.

[cps]

Thanks for the quick reply.

What about if I want to split the signal into three or four signals?

Also, are there any schematics available for simple mixers to recombine the signals?

Cheers,

Chris

[Paul Marossy]

Thanks for the quick reply.

What about if I want to split the signal into three or four signals?

Also, are there any schematics available for simple mixers to recombine the signals?

Cheers,

Chris

I know of one schematic here: http://www.jensen-transformers.com/as/as014.pdf

These Jensen audio transformers are expensive, though. You might be able to get away with using some generic audio transformers, but the performance of them may be less than ideal...

[Ben N]

For effects in parallel, you may not need or benefit from transformer isolation. Take a look at this. It is optimized for two channels, but the idea can be adapted to more using something like the simple mixer at General Guitar Gadgets. Note the phase inverting feature in the Splitter Blend, which can be handy when mixing effects. The buffers are easily replicated as many times as you need--just add an opamp for every buffer you need (or a dual opamp for two, or a quad for four).

[cps]

That's more like what I was thinking of.

Cheers,

Chris

[Vitrolin]

why does the green return have a jfet between the return jack and the op amp?

[Ben N]

Not sure, but I would guess that since U2A can be configured as either an inverting or non-inverting opamp, depending on whether S1 is open or closed, and in inverting mode the input impedance is quite low, Q1 is there as a buffer--which makes sense, since Q1 is configured as a unity-gain, high input impedance source follower. U2B doesn't need the buffer, because it has an input impedance of 1M.

[tempus]

Ya I'm not so sure you need a splitter or buffer at all. I've had my guitar signal paralleled to 4 FX at once and didn't notice any difference in the tone. You may be able to just connect the output of your guitar to each of your FX and then connect the output of the FX to the mixer. I just tried this earlier this week for my pedalboard switcher. One thing that I did notice, though, was that there was less of each effect. IOW my chorus and flanger didn't sound as swooshy as when just used direct. I doubt that this is the result of the initial connection of the guitar to all the effects inputs though. Maybe the wet/dry balance built into the pedal doesn't work as well when things are paralleled?

I'd be interested to know if you find the same thing..

[Ben N]

Without the splitter/buffer, there is necessarily less signal for each of the paralleled effects to use. How much of an effect this has depends on the output impedance of the preceding effect and the input impedances of the paralleled effects. The effects could be what you are describing, or an inability to match levels between effects, or a reduction in S/N ratio. But if you are paralleling off of a good buffer, not splitting the signal too many ways (i.e. not >2), and all of the paralleled effects have hi-Z inputs, you should be ok without the active splitter.

[Paul Marossy]

If you plan on having these paralled effects connected to two seperate amps, I recommend that you use isolation transformers. If you don't, you might end up with a ground loop problem when you connect the grounds of two different amplifiers together.

EDIT: On the ROG splitter-blend schematic, is that Vref switch on U2A supposed to be something intended to help isolate the outputs and prevent a ground loop problem?

[MikeH]

The nice thing about the ROG splitter blend is that it's two parallel effects loops, so essentially it's a buffered splitter and a mixer in one.  Which is a little easier to deal with rather that building a splitter and a mixer separately.  Of course if you're going to two different amps, than it's no big deal.

[Ben N]

I was addressing myself to the OP's question, which had to do with mixing effects. Of course, separate effect chains going to separate amps is a different challenge, which as Paul pointed out does not require return buffers or mixing, but does raise the spectre of ground loop hum and the need to isolate signals and grounds. Two different situations with entirely different solutions.

[Paul Marossy]

I was addressing myself to the OP's question, which had to do with mixing effects. Of course, separate effect chains going to separate amps is a different challenge, which as Paul pointed out does not require return buffers or mixing, but does raise the spectre of ground loop hum and the need to isolate signals and grounds. Two different situations with entirely different solutions.

I only brought it up because I know some guitarists like to do that. One such musician is Allan Holdsworth.

[Paul Marossy]

I'm going to try this ROG splitter/blender thing. I've been toying with the idea of paralleling effects for a little while, but not using seperate amps, just to blend different effects together. It seems to be just the right circuit for the job...

[tempus]

I'm gonna try it too, with my switching system - I plan to parallel all the FX and ground the ones I don't want on as a bypass - hopefully silently...

[norbizzle2012]

i know a good mixer schematic

http://www.electronics-lab.com/projects/audio/025/index.html

ive been meaning to try this one but i dont have enough parts for now. just read the directions on combining all 3 stages.

[Paul Marossy]

I finished building the ROG Splitter-Blender today. Pretty cool little thing to have at your disposal. Time to do some experimenting! 

[Paul Marossy]

Here's a couple of pictures of my ROG Splitter-Blender:




The enclosure was recycled from from the T.M.K. project which I never really used. A little bit of JB Weld filled the holes from the bypass switch and the LED indicator.

[trixdropd]

Here's a couple of pictures of my ROG Splitter-Blender:




The enclosure was recycled from from the T.M.K. project which I never really used. A little bit of JB Weld filled the holes from the bypass switch and the LED indicator.

So what exactly does the pedal do?