Thoughts/Ideas on Pedal Controller Concept

Projects General Guidance
1

A little info on "Why?" .....

My son is a bassist/guitarist and was looking at VERY pricey commercially available controllers. One that does what he needs costs in the neighborhood of $1000 USD. Not exactly cost effective for someone with limited funds and only playing a handful of gigs each year (usually, for next to no pay).

The idea seems like it could be handled with an Arduino (or 2) and cost way less.

Ideally, the controller would allow him to select up to 5 or 6 pedals (out of 10 or 12 on his board) and assign each to whichever foot switch he chooses. Then allow him to store that particular configuration. Thus, allowing him to "recall" a particular configuration at a later time with the click of a button or 2.

At this time, I'm only looking in to accomplishing what I've described. Maybe, if this works out, I'll look in to actually controlling, via Arduino, the actual pedals as well. But with my limited Arduino/electronics experience, I think this concept is a pretty big task for me to accomplish. So, I'm not going to bite off any more for now.

Attached is a "diagram", if you will, of what I'm thinking. I know there is a LOT more to it than what I have shown. I did this, more or less, to get a grasp on the "flow" of things.

For now, I'm looking into using a Multiplex and Light Dependent Resistors to route the audio signal to where it needs to go. It's my understanding, and I could be wrong, that they don't add much, if any, noise to an audio signal.

Have a look at it and let me know your thoughts. A better way? Pit falls? Noise issues? My eyes and ears are open?

(Much easier to view if you download it)

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Going to rethink the use of LDRs. Seems even the lowest valued lighted resistance LRD I can find would probably cause some serious issues having to pass through possibly 10 of them. Not to mention the environmental issues.

So far, opto-isolators are moving to the top of that list.

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2

If you are wanting to switch the guitar input between multiple pedal choices, would a rotary switch do the job?

A 12 position rotary switch is under US$10.

3

bigred1212:
If you are wanting to switch the guitar input between multiple pedal choices, would a rotary switch do the job?

A 12 position rotary switch is under US$10.

Rotary switch - Wikipedia

I suppose it could. But I'm thinking he's looking to make the process fairly "instant". He's one of those that has no idea how people managed to live years ago without remotes, microwaves and cell phones.

My thought was to get one of those "50 pedals in a box" things. I think they more commonly called "Multi-Effects" pedals. But he likes his mostly analog pedals.

EDIT:
After reading through your reply again, I'm unsure if you understood the concept. He wants to create a chain of pedals from the 8 or 10 on his board and put them in whatever order he chooses for the desired end effect. Then save it. Then if he needs a different chain he can build that one and store it too. Thus allowing him to customize his signal chains and change them to a stored preset on the fly.

4

DangerToMyself:
Ideally, the controller would allow him to select up to 5 or 6 pedals (out of 10 or 12 on his board) and assign each to whichever foot switch he chooses.

So this "pedal" is not what I think it is (i.e. a pedal: something to put your foot on), or your sentence doesn't make sense.

For now, I'm looking into using a Multiplex and Light Dependent Resistors to route the audio signal to where it needs to go.

What does an LDR have to do with audio signals? What is the purpose of those LDRs even?

So far, optoisolators are moving to the top of that list.

An optoisolator is a very different part from an LDR. Replacing an LDR by an optoisolator makes as much sense as using an LDR to route audio signals, as in: none. By the way, phototransistors like the TEMT6000 are also dirt cheap and offer a great alternative to the LDR. Maybe not as dirt cheap as an LDR, I think they go at a few times that price even, but you're still talking about US cents kind of costs.

5

wvmarle:
So this "pedal" is not what I think it is (i.e. a pedal: something to put your foot on), or your sentence doesn't make sense.

What does an LDR have to do with audio signals? What is the purpose of those LDRs even?

An optoisolator is a very different part from an LDR. Replacing an LDR by an optoisolator makes as much sense as using an LDR to route audio signals, as in: none. By the way, phototransistors like the TEMT6000 are also dirt cheap and offer a great alternative to the LDR. Maybe not as dirt cheap as an LDR, I think they go at a few times that price even, but you're still talking about US cents kind of costs.

Points taken. Thank you.

Care to suggest a better, or more appropriate way to route audio through a user customizable path that won't add a ton of noise to the audio signal? And be cost effective? As anyone can tell, I'm no electrical OR audio engineer. But then again, if I were, I probably wouldn't be looking to use an Arduino. :smiley:

6

I think that is a large part of why that commercial part costs that much. Routing audio without adding noise is not trivial, that's what I know about it, and that's also about it. You'll be much better off finding out about that part on an audio/electronics forum, not here.

If you need ideas on the general control part of it, that's what me and most other regulars here know a lot more about.

7

wvmarle:
I think that is a large part of why that commercial part costs that much. Routing audio without adding noise is not trivial, that's what I know about it, and that's also about it. You'll be much better off finding out about that part on an audio/electronics forum, not here.

If you need ideas on the general control part of it, that's what me and most other regulars here know a lot more about.

Your previous reply got me thinking that I was following the wrong lead dog. So, I went looking for more info on "Audio Switching". It would seem there are WAY better methods. Not to mention seemingly WAY more simple to implement. Thankfully, I can't find the original article I built my "concept" from. Hopefully, nobody else will find it either!

Researching Analog Cross-Point Switches, which seem to be the best way to go. However, they are typically expensive. Also, looking at using multiple Analog Multiplexers (like the CD4051). And that will probably be the way to go (for me anyway). I'm unsure about any noise injection issues these may have. But with the right chip, I doubt it would be noticeable in this case.

Have it in my head that I would need 10 channels at each foot switch output to send the signal to one of up to 10 pedals. And 7 channels at each pedal's output to send the signal to the next foot switch or output jack.

Can anyone tell me if I'm on the right track now?

8

DangerToMyself:
Have it in my head that I would need 10 channels at each foot switch output to send the signal to one of up to 10 pedals. And 7 channels at each pedal's output to send the signal to the next foot switch or output jack.

Totally lost as to the meaning of this.

9

wvmarle:
Totally lost as to the meaning of this.

The CD4051 is an 8 channel multiplexer. Those are the channels I was referring to. IF, that is what had you lost? And I guess "for each" would have been better than "at each".

And I probably shouldn't have typed that out. It was me sort of thinking out loud. :smiley:

10

I quoted the confusing part.

Electronic parts are not the problem. Whether the part is suitable to switch audio without loss of quality, I have no idea.

11

I'm getting the idea that the pedals are little self-contained audio devices. They have a single input and a single output. There is a footswitch on top and maybe a few knobs on the back. Am I right?

Usually you would chain together a few pedals so that you can add an echo to a Jimmy Hendrix effect or change them around to add Hendrix to the echo, which will sound different. Am I right?

If you need to change pedals during a performance you obviously don't want to get down on you knees changing plugs.

So the solution is simple: use a single digital signal processor with all of those effects chains pre-programmed. Then the footswitches or other inputs can be flexible.

The Teensy processor can be programmed in Arduino or it can be programmed with their own audio effects system. You can draw boxes with different effects on the screen and just draw lines between them to control where the audio goes. With a little actual progamming you can have it controlled by buttons or anything.

I know musicians like the effect they get from one battered piece of equipment from 1974 but with some work in the effects studio, anything can be recreated digitally.

13

MorganS:
I'm getting the idea that the pedals are little self-contained audio devices. They have a single input and a single output. There is a footswitch on top and maybe a few knobs on the back. Am I right?

Usually you would chain together a few pedals so that you can add an echo to a Jimmy Hendrix effect or change them around to add Hendrix to the echo, which will sound different. Am I right?

If you need to change pedals during a performance you obviously don't want to get down on you knees changing plugs.

So the solution is simple: use a single digital signal processor with all of those effects chains pre-programmed. Then the footswitches or other inputs can be flexible.

The Teensy processor can be programmed in Arduino or it can be programmed with their own audio effects system. You can draw boxes with different effects on the screen and just draw lines between them to control where the audio goes. With a little actual progamming you can have it controlled by buttons or anything.

I know musicians like the effect they get from one battered piece of equipment from 1974 but with some work in the effects studio, anything can be recreated digitally.

You are correct with both of your 2 questions. And I will certainly have a look at the Teensy audio effects system you spoke of.

Delta_G:
I don't mean to discourage you. It will be a cool project. I just don't want to leave you to fool yourself into thinking that it's going to be a money saver.

Your wisdom is much appreciated. As it stands, I've already learned quite a bit in just researching the idea. For me, that's where all the fun is with the Arduino. And of course, that goes hand in hand with the challenge of it all as well. If I never order the first part for this "concept", I'm still better than I was yesterday.