I tried making a Theremin with the NTS-3 kaoss pad kit | logue.sdk Development Log

Introduction

The logue.sdk allows you to develop not only built-in effects but also custom effects and sound sources, and since the NTS-3 kaoss pad kit was so interesting, I decided to use this logue.sdk to create a Theremin-style sound source.

In this article, I would like to introduce the development process and the trial and error involved.

Why I decided to make it

Originally, when performing dub mixes, I felt there was potential in a technique where I would record filter-like effects in real-time by moving the points of FabFilter Pro-Q 3 on a DAW with a mouse.

I have also incorporated that technique into the sound source below.

I thought that this kind of XY pad-like operation would be a good match for dub mixing, so I even tried using a touch monitor for PC in the past. However, it just didn't feel right.

After that, I learned about the iPad app Loopy Pro, and when I connected an iPad and an audio interface to use it like an external effector, I found it to be extremely interesting.

It was in that context that I learned about the existence of the NTS-3 kaoss pad kit.

I struggled with whether to choose it over a regular KAOSS PAD, but the NTS-3 had the major appeal that I could develop my own sounds and effects using the logue.sdk.

"Wouldn't it be incredibly fun if I could develop it freely?"

That is how it all started when I introduced it.

And while I was making a few effects,

"Since I'm at it, why not make the instrument itself instead of just effects?"

I decided to take on the challenge of developing a Theremin-style sound source.

Preparing the development environment

First, to develop with the logue.sdk, I installed the following software on my environment (Windows 11).

• Docker Desktop

• Git Bash

• Visual Studio Code

• KORG Kontrol Editor

For this logue.sdk development, I mainly utilized Gemini for everything from environment setup to coding.

Having Gemini write the code

logue.sdk code is written in C++.

Since I have almost no knowledge of C++, I proceeded with development this time while utilizing Gemini.

Basically, I had Gemini write the code and then verified its operation on the NTS-3. If there were any points of concern or parts that differed from my vision, I would convey that to have the code corrected and then verify the operation again—a process I repeated many times.

This Theremin-style sound source didn't turn out exactly as I intended from the start either. I made adjustments little by little by feeding back the discomfort and points for improvement I felt while actually playing with it to Gemini, and finished it into its final form.

Rather than writing the code line by line myself, it felt closer to developing while conveying specifications and ideas like "I want it to behave like this" or "I want to change this part here," and I truly felt the fun of development utilizing AI.

Trial and error to get closer to the Theremin sound

First, I asked Gemini,

"I want you to make a synth that produces a sound like a Theremin."

and tried it out.

However, what came out had a very different impression from the Theremin I hear on YouTube and other places.

After that, I made corrections many times.

In the first version,

• X-axis: Pitch

• Y-axis: Vibrato depth

I had set it up this way, but it didn't quite match my image.

So, I re-researched the sound of the Theremin.

Upon investigation, I found that the unique timbre of the Theremin is not just a simple waveform, but a combination of elements such as:

• a simple sine wave as the base

• resonance from the speaker and wooden cabinet

• constant fluctuations in pitch and volume due to subtle hand movements

which together create that unique expression, reminiscent of a human voice or a violin.

So next, I tried adding things like:

• a low-pass filter

• room reverb

and so on.

However, it still didn't reach the vividness of a real Theremin.

Coming up with the idea of combining it with a Tumba box

After thinking about it a lot,

"Wouldn't it be better to use a speaker as a resonator, just like a Theremin?"

I arrived at this idea.

So, I decided to use the Tumba box I had made previously.

Furthermore, I learned that in logue.sdk, I can assign unique roles not only to the XY pad but also to the DEPTH knob next to it.

A theremin is essentially an instrument played by using the position of your hands in three dimensions.

So, this time, I decided on the following configuration:

• X-axis: Pitch

• Y-axis: Volume

• DEPTH (Z-axis): Range switching based on left/right volume difference (approx. 1 to 6 octaves)

I set it up this way.

The plan was to have the logue.sdk output a simple sine wave and send that sound to a Tumba box to create a characteristically theremin-like sound.

I explained these specifications to Gemini and had it do the coding again.

Impressions after actually using it

When I tried out the finished product, I felt that the sound had become quite theremin-like in its own way.

A reference audio clip is posted at the end of the article.

However, when I actually tried playing it, I found that because the NTS-3 kaoss pad kit is so compact, fine pitch control felt difficult.

That is where the iPad comes in.

Using an iPad as a MIDI controller

Upon researching, I found that an iPad can be used as a MIDI controller for the NTS-3.

So, I introduced TouchOSC to the setup.

While you can create screens on the iPad alone with TouchOSC, I personally found it difficult to work with, so I created the layout using the Windows version of TouchOSC Editor and transferred it to the iPad for use.

As a result, I was able to play using a larger screen, which allowed for much more delicate operation than the NTS-3 unit itself.

Furthermore, I was concerned about my finger movements catching due to the friction of the glass film, but I was able to play smoothly by using the following type of finger cots.

Summary

This time, I tried developing a Theremin-style sound source using the logue.sdk.

In reality, I have created several other effects and sound sources besides the Theremin, and I am amazed by the high degree of freedom of the NTS-3 kaoss pad kit.

I would like to write an article and introduce it again if I make something interesting.

The NTS-3 kaoss pad kit, which can be enjoyed as both an effector and an instrument, was personally a piece of equipment that was very rewarding to play with.

And thanks to this equipment, I have started to challenge myself with the development of digital sound sources and effects that I had not touched before. I feel like I have stepped into another new rabbit hole before I knew it.

I would like to continue exploring new ways to use it and interesting ideas while making full use of it in the future.

Reference audio

This is a sample audio source using the kaoss pad kit + TouchOSC + Tumba box.