My first Stompbox, a mini (matrix) mixer

[Ayacombe]

I have a specific need for a pedal, which to my surprise is not already available. I need to build a two channel effects loop, with two send/returns for both channels. It's basically a two channel mixer with two aux/sends.
Here is a quick diagram of what I need



Both channels are always "on" and the switches are used to activate each loop.
Each send/return loop has blend knobs for both channels.

I have good soldering skills but only a very basic knowledge of electronics.
Is this a doable project for a semi-noob, and do you have any tips on where to begin, similar projects or resource-sites?

[antonis]

Hi & Welcome..

I'm not sure what you want but you might find it here:
http://beavisaudio.com/projects/looperswitcher/

Then, you should decide about IN-OUT-BLEND need for buffering..

[Ayacombe]

Thanks. This seems like a good resource.
I am not sure what you mean about the the IN-OUT-BLEND need for buffering though.

[ElectricDruid]

Welcome!

Do both inputs go out to both Loop Sends? And then the Blend controls mix in the Loop Return signal into Output 1 or Output 2?

I don't understand how it's supposed to work, sorry. The diagram hides too much in the box.

[Ayacombe]

Thanks!
Yes both inputs go through both sends. The blends are controlling how much of each send (effect loop), is blended with each input.
The inputs are parallel, and do not mix. They should just go through the same effects and to two parallel outputs

Does it make sense?
I will make another diagram later

[ElectricDruid]

Yes, that makes sense, but the Loop Returns will *always* have both inputs mixed together - is that what you want?

For example, it's impossible to set it up to do In1->Loop1->Out1 and In2->Loop2->Out2.

[antonis]

I am not sure what you mean about the the IN-OUT-BLEND need for buffering though.

It's all about mix/blend output impedances in conjunction with next effect input impedance..

[Ayacombe]

Yes, that makes sense, but the Loop Returns will *always* have both inputs mixed together - is that what you want?

For example, it's impossible to set it up to do In1->Loop1->Out1 and In2->Loop2->Out2.

It’s not what I’m after, but you’re right - of course they will be mixed together…if they’re mono. But if they’re stereo, I guess it’ll work, right?
Then first switch would activate e.g. distortion on both channels, and the second switch would activate reverb on both channels

[Ayacombe]

Maybe this makes more sense. This is half of what I want to build, but it could also work with my board.
I have stereo pedals in my loop, so I guess it should be possible to send two inputs through them without blending the signals?

[idy]

What you have now is just two splitter blenders. One example:
http://www.runoffgroove.com/splitter-blend.html

But running two would take a 4pole bypass switch and no LED... or relays or CMOS or opto isolators or something. I think.