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Korg NTS-2 Oscilloscope Review

A Handy Utility for Getting Started with Modular

Robin Vincent · 12/23/24

Korg's Nu:Tekt line first appeared in 2020 with the NTS-1. It was a Monotron-sized digital synthesizer kit that you screwed together to produce a cool and very playable virtual analog synth. It had a remarkable effects engine and an external input that made it a usable effects box, but best of all, it had the same "logue-SDK" technology as the Minilogue XD and Prologue synthesizers, which meant you could load custom oscillators and effects. It was a stunning array of features packed into a tiny box for under $90.

The NTS-2 is nothing like it. It's the same size box, comes under the Nu:Tekt banner, and you have to screw it together, but the functionality is completely different, almost to the point where they feel unrelated. That doesn't really matter because the NTS-2 has its own thing going on; it's just essential to understand they are very different products.

In the NTS-2, we have a very handy utility device that's particularly useful for modular users and people with a penchant for DIY. Its primary function is as an oscilloscope, but it does have a few other tricks up its sleeve, which we'll discuss later. Oscilloscopes are one of those tools that you don't immediately think is that useful. You can make music quite happily without analysing waveforms or taking measurements. But over time, particularly with modular, you get to wondering if there was an easy way to visualize what's happening between your modules.

The obvious solution in Eurorack is the mighty Mordax Data Multifunction tool that you see painting waveforms in all the best Instagram modular jams. But it's a bit expensive for some budgets, and wide for something you'd only see yourself using occasionally. Analog oscilloscopes rescued from your old school's physics lab are cumbersome, complex and tricky to patch into. Just before the NTS-2 came out, I'd ordered a similar-sized digital scope from China that worked pretty well once you'd deciphered the instructions and worked out how to patch it in. The NTS-2 cuts across all these options with a reasonably priced box with the perfect set of features and connections for Eurorack explorations.

The Details

The NTS-2 is in fact, an oscilloscope, a tuner, a spectrum analyzer with a dedicated Fast Fourier Transform mode, and a dual waveform generator. It can be powered by two AAA batteries or via a USB-C port. On the back, you have a row of minijack connectors including two dual-channel inputs, which either offer two mono channels, stereo or four channels using stereo-to-mono adapters, two dual-channel Thru ports for sending the input straight back out again, and two mono outputs for the signal generators.

The 2.8" 240 x 320-pixel color screen fills a large chunk of the front panel. Underneath you have a row of five menu buttons, and to the right is a clicky knob that changes parameters and also has a click if you push down on it. The Start/Stop button enables the display and you've also got an indication of active outputs on two LEDs.

Physically it's neat, light and very approachable. It's perhaps a little too light at times as it can often get pulled off the desk by cables and is not always an easy thing to site amongst your modular setup. It does come with little Perspex wings you can screw on the side to act as a stand, but I found these didn't help in any real situation. However, the fact that it isn't hard-wired into your rack has lots of advantages and versatility that a mounted one doesn't. You can take it about the studio, plug it into different things, take it with you for some mobile music scoping.

Oscilloscope Functionality

If you are anything like me, then you'll probably use it most as an oscilloscope or, rather, as a visual aid to explore how synthesis works. Using stereo-to-mono adapters on the two inputs, you can display four channels of waveforms, either overlayed or shrunk, to fill a quarter of the screen height. I would tend to be looking at one thing in which case it could fill the whole screen.

Using the buttons, you can decide how you want the waveforms displayed. You can set the vertical display range for each input from 10mV to 10V and the global time from 50uS to 1s. You also have some horizontal offset to move the starting point of the waveform. But that is it. There's no vertical offset, no frequency display, and no cursors for taking readings, which are very common in regular scopes. While you can take eyeball measurements using the grid, they are not going to be particularly accurate.

However, that's not really within the scope of this scope. We are musicians rather than electrical engineers, and I believe the intention of the NTS-2 is to give us visual feedback to help us deepen our knowledge of synthesis techniques. We're not really here to do detailed analysis. Viewing waveforms and watching them change, morph and move as we filter, modulate or fold is an awesome thing that has undoubtedly changed my approach to modular, and so for me, it does enough.

As a bonus, there's a "Lissajous" mode that uses two waveform inputs to visualise XY oscilloscope line art - you should definitely check that out.

Spectrum Analyzer

The FFT mode combines a single input waveform display with a graph of frequency against amplitude. It's a brilliant way of seeing harmonics present in different waveforms and how they are shaved away as you close a lowpass filter. In fact, if nothing else, seeing a square wave de-evolve into a sine wave by filtering out harmonics for the first time will blow your mind.

You can change the frequency range on screen from 20Hz to 1kHz or all the way up to 20kHz. You can also change the position to view different parts of the frequency range zoomed in. As with the scope, there are no tools to help you measure anything you can see, and the frequency value labelling is really small and difficult to read. Again if your goal is understanding rather than analysis, then the Spectrum Analyser is plenty good enough.

Waveform Generator

The NTS-2 can generate two independent signals tied to the two outputs on the back. These can be oscillators, LFOs, envelopes, clock pulses or noise. The display splits into two and gives you a visual of what you're outputting, plus two panels of parameters for editing with the encoder. It's also possible to monitor an input on the display.

As an oscillator, you can choose from sine, triangle, square and a sawtooth in both directions. You can set a level and choose a pitch in either Hz or quantized to musical notes. There's a shape control that acts as pulse width modulation on the square wave, but it also does some nice shaping of the other waveforms. You can also shift the phase, which can be interesting when you use the two oscillators together. LFO mode is exactly the same, giving the same frequency range of 0.01Hz to 10kHz but with a polarization setting instead of wave shaping. Changing the frequency takes a massive amount of encoder twiddling.

Noise gives you a choice between white and pink flavors. Pulse mode gives you a square wave clock pulse where frequency is replaced with a BPM or millisecond setting, which is very useful. Envelope mode gives you a linear or exponential sawtooth wave with a decay from 1ms to 10s. You can push the shape to balance anywhere between zero attack and full decay, and full attack with no decay.

In all the modes, you can set it to cycle constantly or set it to a 1-shot, or to cycle when pushed. You then use the Start/Stop button to trigger the output. This is particularly useful in envelope mode.

This is all great, fabulous and useful stuff. However, none of it is externally controllable. You can't play the oscillators, modulate the LFO or fire the envelopes with anything other than your fingers. As an LFO, clock or noise source, it can certainly be useful but other than some droning, or for the fun of generating some waveforms, the oscillators don't have a lot of use.

Tuner

Lastly, we have a tuner. You can view it as a needle or a meter, have the waveform displayed or not and calibrate it to any frequency you wish. It's excellent and useful, if a little slow.

Conclusions

The Korg NTS-2 is not a brilliant oscilloscope for scientific purposes, but it is an extremely useful tool for musicians and synthesis fiddlers. For visualizing waveforms and helping you understand what happens when you modulate, when you filter, when processing signals, it's top notch, and I couldn't recommend it enough. I build a lot of Eurorack modules from kits and it's become a vital tool in calibrating oscillators and testing circuits. And when I'm learning or demonstrating Eurorack modules it's a great way to support the understanding of what's going on.

The Waveform Generators have a lot of potential that's not being fully realized at the moment, though they are still a useful feature. If you could send it CV to control the oscillators or trigger the envelopes it would elevate it to a whole other level of usefulness.

If you are looking to measure or analyze voltages and audio signals, then the Mordax Data or a professional oscilloscope would be a better bet. But if you're making music and exploring sounds then the NTS-2 would be the perfect companion for getting deeper into what's actually happening.