Audio Circuit Switching with Spark

I was wondering if any of you have prior experience with the Core in audio relaying. I wanted to create a Core application that allows digital switching of sound signals. I was thinking a hub that I would hook effects pedals into, then turn the signals leading to them on or off according to which effects I desired. And is there a way to attach it 1/4 inch sockets for guitar jacks,etc to an Arduino board. Let me know what ya got!

@TtheShow did you have something working before?

I’m not into music but the electronics behind your hobby seems interesting and an intriguing idea!

Can you share more and maybe I can make some protoboards even to help test stuff :slight_smile:

EDIT: You got me into reading!

HI @TtheShow

I am not sure what you have in mind here either–did you mean moving real-time audio over Wifi with a spark core? That would be very doable but not easy.

Or did you mean doing the control part, the equivalent of stomping on the pedal. It would help a lot if there was an Arduino or other example, but if this is a completely new idea, that’s great too!

There is a thread on Open Sound Control, which might help you, over here:

Something similar to a “stomp box” is exactly what I mean, but I’d like do so without physical buttons. I plan to write an application that will allow the user to make presets and switch between pedals quickly by selecting a preset on the app.

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Of course this would require 1/4 inch inputs and a way to turn each off/on. Does this necessitate the high-watt breadboards, typically used for appliance switching?

Similar to:

TtheShow, if I understand correctly, you want to feed a number of effects pedals into a box (which has a Spark in it). I assume the audio is being FED to the pedals separately. Then, you want he spark to switch which audio (from the pedals) are fed OUT of the box to an amp I assume. So the Spark controls which of the pedal audio is mixed in and outputted (to an amp I assume). Correct?

Hi @TtheShow

You could do what want, with some limitations, with the relay shield but there might be some audible click or pop when you switch. This CoolSwitch box looks like a simple switch so it might be about the same.

The relay shield has four relays so that might limit you to four effects, but other boards with 8 relays can be found on ebay for not a lot of money.

You have two challenges: (1) you need to design the switching electronics which can be as simple as using the relay shield as switches or as complex as finding an audio switching IC with i2c like a PT2314 or similar part. And (2) you have to write the software to control this, which might be the easier part actually, if you use Spark functions and variables.

@TtheShow I’m liking what i see!

Do you have an existing ‘CoolSwitch’ box or similar?

Let’s hack it up with some wires and get something running before looking deeper :smiley:

This is correct! Any info would be helpful or resources!

Ok, should I send screenshots of the switch box opened?

TOTALLY! How about the specs, brand etc?

I will do that! I’ll get all of the above to you. The problem is- I am not an electrical engineer by any means, just an app developer, so if you have any info based on what you see let me know!

That’s not a showstopper. I’m not a web/app developer but i want to learn it :smile:

I’m sure with the help of :spark: community we can get this going!

What else do you have? Relay shield? Some wires? Some transistors?

TtheShow, there are plenty of electrical engineers here (counting me) and I have 10+ years of audio-visual design so we’ll figure out. I need to understand the following:

  1. Is the audio single (mono) or dual-channel (stereo)?
  2. Is the non-effect audio fed to each pedal directly or through the “box/switcher”
  3. Does the output of the “box/switcher” go to an amp or an audio mixer?

The cool switch is a very basic a/b or a AND b selector. How many inputs and how many outputs are you looking for and what combination of ins and outs?. This will define whether it is a many-to-many switcher or a many-to-one switcher. :zap:

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@TtheShow I just had a conversation with my cousin who plays with the guitar.

We can’t convince ourselves why is there a need for a wirelessly controlled switch. :smile:

Wireless from guitar to switch is like the norm to take away the cable and move freely…and that’s legit…

What’s your take?

The purpose would be to create a switch box without the necessity for the musicians to physically interact with the stomp box. I would wrote code that the musician could preprogram around the pedals’ inputs. Imagine a scrollview application, where a song on a setlist is selected, then the microcontroller arbitrarily turns effects on and off to gain the desired sound. It is fairly simple but useful, as I hate stompboxes live.

There is certainly a need for mono input jacks on the Arduino board itself. I want to make the “stomp” pedal which is often used on stage into a single preprogram-able application via Spark. I’m sure you are familiar with 1/4 inch “guitar jacks”, but I need to figure out how to activate/deactive the signal to each effects pedal without popping or “clipping” when I make switches via the application.

The non-effect audio is simply fed from a guitar’s/instrument’s signal into the pedal board (in this case the bread board with a 1/4 inch socket) and out to an amplifier. By default, the pedal should have an “open” or clean sound as there is no distortion of the signal to the amplifier. However, I want to make it so external effects pedals, which are constantly on, can either have their signals put on “standby” or “active” depending on the musician’s uses. Obviously the configuration can be vast, which is why I want to try it!

I’d like to have 1 1/4" input, four 1/4" inputs for effects signals, and 1 1/4" output. Is this feasible?

This is kinda cool, but I’d like to physically attach inputs and outputs, just like a pedal switcher:

Essentially, I want to activate/deactivate signals to these:

I am just wondering how the signals will be affected as they pass through the Arduino hardware.

@bko much appreciated advice. The code I can do, the hardware I am still trying to debug.