Multi Effect for DIY Modular

The project I am working on using the Daisy Seed is a Multi Effect for my very non-standard DIY modular.
I had been looking for a VCA to use in my modular, but since it’s mostly a bunch of Arduino Nanos running off of a USB HUB and built on a shoestring budget I was having a hard time finding one. I think I stumbled over the Daisy just looking through projects on kickstarter and thought that it would do the trick at a reasonable price. Of course, once I read up on it I realized it could do much more.

So this is the result of my project so far:

The signal path goes like this:
Input > Variable state filter > VCA > Switchable effect > Reverb > output
Both the input and outputs have volume control.
The Variable state filter can be switched between High Pass, Low Pass and Band Pass.
The switchable effects, right now, are Decimator and Fold but I want to add more soon.
The jacks on the bottom are breaker jacks so I can connect LFOs and the like.

I designed the panel and the knobs in Solidworks and printed them on my Creality CR-10 mini. It’s not the best quality printer ever but it does the job and I like the look of it.

Here is a view link to the Code:

If anyone wants to have a look and see if there are any horrible errors or areas of improvement I’m all ears :slight_smile:

Is there any particular reason why you’re not doing it in stereo? I guess you may have no stereo sources in your system, but you could use it to process 2 independent channels. Or you could take 2 mono inputs, process with some kind of stereo panner/mixer and then apply effects in stereo. Seems like you could get much more interesting results this way.

Yes, the reason why I’m not doing it in stereo is because my modular is completely mono.

Right now I have a passive summer/mixer in my system and I could definitely use the Daisy
to replace that and add effects to channels independently like you say, but since I’m using Arduino
which until very recently couldn’t access more than a little bit of the Daisy’s memory I have been running
in to a lot of problems with just adding one more effect to the system.
I tried adding different effects to the two channels in my system but I kept running out of memory :frowning:
Right now I’ll either have to use the new functions in the Arduino library to access more memory and store variables and arrays there or just bite the bullet and learn C++ and try to re-do the project.

Not sure what I’ll do yet.

One thing I’m definitely doing soon is changing the output to stereo, changing the output pot and jack and adding a little amplifier so
I can comfortably drive a pair of headphones from the output.

They’ve recently released update to Arduino Daisy library that lets use SDRAM like with normal C++ patches - Arduino Limited Memory Access?

So at least memory should no longer be a problem.

I’ll have to get cracking on that later, right now I’m moving on to
trying to make a functioning ADSR that’ll work with my sequencer and the Daisy.
Once that’s done I’ll continue working on my Daisy code.
I might actually order a second daisy just so I can keep the one I’ve made in my modular while I work on my code.
I’ll see.

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Hello! I’m looking to build something similar to use for my modular gear as well! I’m curious on the hardware side of things, and had a few questions for ya!

  • what hardware did you use to get the signals in and out of the Seed? Did you use any buffering/scaling?
  • Did you use the Seed’s Audio in/out pins?
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Greate project @Saotome!

I have exactly the same questions as @Reesepuffs. Next on my todo-list is a Daisy Seed-based FX unit, and it would be cool to include CV modulation into it.

Well, I could always look at the Daisy Patch circuit and copy that! :slight_smile:

I will do my multi-fx-unit in C++ code as soon as I finish my OscPocketD (OscPocketD - Portable music tool (sequencing drums and synths) - #10 by StaffanMelin)!


That’s true! I was thinking about doing something similar to the Patch! Or, I was thinking of using the schematic from the Petal. Both utilize the MCP6002 I believe? I don’t plan on using CV though, just a strict audio in, add effect, audio out


I’m sure I should have used buffering and scaling, but I’m way too much of a noob
so I just connected mono jacks to the in and out pins of the Daisy with volume pots in between and it seems to work ok.
When I have the time I will be adding a trimpot or putting the volume pot in a resistor network because the output of my oscillators is a bit to hot for the daisy. It hasn’t damaged it or anything but It does seem to go a bit wonky if I turn up the input volume too much. I might as well limit the volume permanently so I don’t have to worry about accedentally turning it up too high.

I have, however, put zener diodes on the CV inputs to protect them if I ever try to connect another CV source than one I’ve built mnyself.
The LFO’s and ADSR I’ve built are all 3.3 volt but I’ve seen other CV sources going as high as 10 volts.


Thanks for the input, @Saotome!

So at the moment the bottom jacks are not connected?

Thanks for the response!

Did you use the Audio in/out pins? Or the ADCs?

Oh yes they’re connected. They are switched jacks connected to the analog ins of the Daisy.
When no CV is connected the jacks are bypassed and the corresponding analog inputs on the daisy get their signals from the potentiometers, but when you connect a CV it breaks the connection to the potentiometer and the input gets its signal from the CV.

I hope I explained it better this time :slight_smile:


I used the audio ins and outs for the audio and
analog pins for CV and potentiometer control.


Ah, of course! Thanks! :slight_smile: