Korg MS-20 Mini review

The MS-20 Mini by Korg is a recreation of one of the most iconic and sought-after vintage analog monophonic synthesizers of all time, the Korg MS-20. When the MS-20 Mini was launched a few years back, it was one of the major forces that helped spearhead the massive comeback of analog synthesizers in the mainstream market. It had a tried-and-true sound and was pretty affordable compared to many other options on the market at the time.

Additionally, it is one of the best keyboard synthesizers for beginners looking to learn more about analog synthesis, due to its very clear signal path and knob-per-function interface The original was especially known for its raw, gritty sound and screaming, dual filters; this new version delivers on both of these fronts, but is significantly smaller and more portable. However, how does this synth stack up in today’s heavily-saturated market of analog synths?

In this article I will be delving into the various aspects and features of this synthesizer, including the following:

Hardware Overview
Voltage Controlled Oscillators
Dual Voltage Controlled Filter
Envelopes
Modulation Generator and beyond
Patch Bay, External Signal Processor

To better help you, take a moment to check out the interactive guide below, which allows you to directly compare the Korg MS-20 to other notable synthesizers on the market:

Photo	Model
	Roland JUNO DS61
	Roland JUNO DS88
	Korg Kross 2
	Korg Minilogue
	Roland JD-XI
	Yamaha MX88
	Behringer Monopoly
	Novation Impulse 61

Hardware Overview

The MS-20 Mini comes in a black metal chassis with plastic end cheeks, and looks identical to the original apart from its size. Overall, the build quality is not nearly as solid as the original; in particular the knobs can be a bit wobbly at times. This is only really an issue if you’re particularly rough with your keyboards, and certainly suffices when you consider the price.

The interface is knob-per-function and fully analog, with two voltage-controlled oscillators, high pass and low pass voltage-controlled filters, voltage-controlled amplifier, two envelopes, modulation generator, and a 33-point patch bay. The patch points are mini jack connections instead of the full-size ¼ inch connections you would find on the original. It includes 10 patch cables, which is more than enough for almost every possibility.

Just like the original, it has a 37-key, synth action keybed. On this version, however, it features mini “slim keys” instead of full-size keys. This is the same keybed that would be later featured on the Minilogue synthesizer; the keys are not quite as small as a traditional mini-keys, and has a pretty solid and responsive feel.

On the left side of the keyboard, it has a modulation wheel and momentary button, both of which can be patched to any number of parameters using the patch bay. There are only three connections on the rear of this synth: a DC input for power, a USB B port for connecting to a computer, and a single MIDI DIN input for controlling with an external controller or sequencer. The audio outputs are on the front panel on mini jacks, and has both a regular line output and a headphone output, with a single volume knob for both outputs.

Below, please take a moment to view some of the best selling synthesizers online and see how well they stack up to the Korg MS-20:

BEST SELLERS
1) Yamaha MX88
2) Korg Minilogue XD
3) Roland JUNO-DS88

Voltage Controlled Oscillators

The MS-20 Mini features two flexible VCOs. The first oscillator has four different waveform options: triangle, sawtooth, square, and white noise. The square wave has a dedicated pulse width control which can go through-zero, but unfortunately cannot be modulated with an LFO or other source. This oscillator can be set to four different octaves.

The second oscillator is a bit different from the first. It can be set to sawtooth, square, and pulse waves, as well as a special ring modulator setting. This ring mod is one of the most notable features of the MS-20, and lets you modulate the first oscillator using the pitch of the second to get some very interesting, complex sounds.

Instead of a pulse width control, this oscillator has a dedicated tuning knob, which can go about an octave in both directions. In addition to this, it has octave controls like the first oscillator. It can go an octave higher than the first oscillator (not counting the use of the tuning knob), but not as low.

It is a monophonic synth, so you can only play one note at a time unless you use the pitch tuning controls on the second oscillator to tune it any interval away from the first oscillator. In addition to the tuning on the second oscillator, it has a master tuning potentiometer as well, which controls both oscillators simultaneously.

This is a fine-tune control, mainly for adjusting the overall tuning of the synth. There is also a portamento (also known as “glide”) control next to the master tuning knob. From here, the oscillators pass into a mixer where their volume can be controlled independently.

Dual Voltage Controlled Filter

The filter section on the original MS-20 is perhaps one of the most important aspects of its iconic sound. It features a high-pass and low-pass filter in series. The high-pass is 6 decibels per octave, and the low-pass is 12 decibels per octave. Having two filters means you can shape the sound quite a bit more than on a synth with a single filter; you are able to cut the low frequencies as well as high frequencies.

Both filters have their own independent resonance control, meaning you can have two different peaks at the same time. At about 75% resonance, the filters start to self oscillate, and when you push it further than this the filters start to break up, screech, and distort. This squelching, overdriven character is one of the hallmarks of the classic MS-20 sound.

Envelopes

After the filters, the sound then passes through the Voltage-Controlled Amplifier, and then through the envelope. The MS-20 Mini has two different envelopes, but both are normalized to different locations. Envelope two is normalized to act as a standard amplifier envelope without any patching needed.

This envelope is the more complex of the two, with five stages: hold, attack, decay, sustain, and release. The “hold” feature happens before the attack stage, and does exactly what you would imagine – it holds the sound steady for a certain amount of time before moving onto the next stage.

In contrast to envelope two, the first envelope is only three stages: delay, attack, and release. The delay parameter is similar to the “hold” on envelope two, but instead of holding the envelope open it keeps the envelope closed for a certain amount of time, before reaching the attack portion. By default, this envelope is routed to oscillator pitch, but can be routed to a different parameter using the patch bay.

You can control the amount being sent to this envelope using the “frequency modulation” section below the mixer. These two envelopes give you quite a bit of control over the contour of your sound; however, it should be noted that the MS-20 does not have a dedicated filter envelope like many modern synths. Instead, the filter can be routed to envelope two in the “cutoff frequency modulation” section below the filters. When you do this, it shares an envelope with the amp.

Modulation Generator

In addition to the two envelopes, the MS-20 Mini features one LFO, or Low Frequency Oscillator, in the “Modulation Generator” section. It is relatively primitive, especially when you compare it to the full-featured LFOs on more modern-style synthesizers. There are two potentiometers in this section. The top knob is the waveform control, which allows you to cycle between either square/pulse waves or saw/triangle waves.

When the knob is dead center the LFO outputs either a square wave or a triangle wave. When you turn it to the left or right, the square slowly transforms into a pulse wave, and the triangle morphs into a sawtooth or ramp (reverse sawtooth) wave. The second knob in this section controls the frequency (also known as rate) of the LFO.

This synth is normalized to allow you to modulate certain parameters with the modulation generator without needing to patch anything. This can be done via the “Frequency Modulation” and “Cutoff Frequency Modulation” sections, which are found below the mixer and filters, respectively.

When you turn the “MG/T.Ext” knobs in these sections, by default the pitch or filter cutoff will be modulated by the LFO based on the amount of depth you dial in. In addition to these default routings, the LFO can also be used to modulate other parameters by way of the patch bay.

Patch Bay & External Signal Processor

The extensive patch bay on the original MS-20 was a pretty unique feature at the time. There are a number of different semi-modular synthesizers on the market these days, but back in the 70’s this (along with the other synths in the MS line) was pretty much the only available. In general, there are a lot of interesting sound design possibilities that open up when you use the patch bay on this synth.

That being said, I have found that this patch bay is a bit unusual by modern standards; there are certain things that are simply not possible to achieve with this synth, things that would seem obvious if you have experience using more modern semi-modular or modular synthesizers.

I won’t go over every single patch point in this article, but I will give an in-depth overview of the most notable ones. Like you would expect on a modular synth, it has inputs for modulating oscillator and cutoff frequency for both filters. However, there is no way to control each oscillator separately via the patch bay. Similarly, there is no way to modulate the pulse width of the square waves. These are some unfortunate limitations of this synth architecture.

The modulation generator has separate outputs for both types of waves: square/pulse and triangle/saw. This allows you to use both separately, albeit clocked to the same rate. In addition to this, it also features a noise generator with separate pink noise and white noise outputs.

The sample-and-hold is an important aspect of this synth; it allows you to modulate a signal like an LFO would, but instead of a single cycle waveform the modulation source is a random frequency every cycle, according to the rate via the clock source input. There is also a control voltage input for controlling the oscillators and a keyboard CV output. In addition, there are inputs for the mod wheel and momentary switch for patching any number of parameters to them.

The patch bay also features an external signal input, which gives you the ability to run other sound sources through the MS-20’s filters and amp. Using the external signal processor gives you even more control over this input. When you patch a signal into this processor, it runs the sound through a separate amplifier and a dedicated bandpass filter.

In addition to this, you can also run the signal through a frequency-to-voltage converter and envelope follower if you want to use this external signal as a CV source for controlling the oscillators. There are controls below this section for signal level, low cut frequency, high cut frequency, CV adjust, and threshold level.

One very common usage of the external signal processor is to route the audio output of the MS-20 back into its external input. This is done by patching the output into the input of the external signal processor, and then patching the output of the external processor back into the external signal input on the patch bay.

This way, you have control over the level of the input and frequencies via the bandpass filter. When you do this, you are able to drive the signal even harder into the synth’s filter and amp; the result is a nice overdrive at low levels and extreme feedback and distortion at high levels.

It is very important to note that the MS-20 (original and Mini) operates with Hertz per Volt to control its pitch. This is different from how almost all other modular and eurorack synths work, via Volt per octave. Because of this, you will be unable to control pitch and some other parameters using other modular gear without some sort of converter.

There is one particularly-infamous problem that has been run into on these MS-20 reissues; the amp has a particularly high noise floor. This means when you hold down a note with the envelope open, even if the filters are completely closed, you will still hear some noise at high volumes.

It isn’t much of a problem when using loud, overtone rich waveforms with the filter wide open, as this will mask the noise; however, it starts to become noticeable when you close the filter for quieter, more mellow sounds. This problem seems to have been more significant on older models of the Mini, and is less extreme but still present on newer versions.

Comparison to Similar Synthesizers

Let’s begin with the Korg Monologue.

Korg Monologue

The Monologue is another analog monophonic synthesizer from Korg, the second in the “Logue” line, after the Minilogue. It is not a reissue of an old synth like the MS-20, and as such it has a lot of modern features that the Mini lacks. It is also quite a bit less expensive than the MS-20 Mini. However, it is missing a lot of features that makes the MS-20 so unique and iconic; things like the dual filters and patch bay.

Much like the MS-20, this synth has two VCOs. Oscillator one can be set to saw, triangle, and square, and oscillator two can be either saw, triangle, or noise. Both oscillators have a waveshaping control for all waves, not just the square, which gives you quite a bit more sound possibilities than the MS-20.

Another big advantage is that the waveshape control can be controlled by the LFO, a feature that is sorely lacking on the MS. In addition to a ring modulator, oscillator two also has a hard sync setting.

The Monologue only has a single voltage-controlled low-pass filter with resonance control. Not only does it have a completely different character than the sought-after MS-20 filter, but also lacks any high-pass filter control. It only has one envelope, which in addition to controlling the amplifier can be routed to the pitch of both oscillators, only oscillator two, or the filter cutoff.

It also only has one LFO, which is similar to the one found on the MS-20 except for the fact that it can also modulate oscillator wave shape. Perhaps the most notable difference is that the Monologue has a powerful 16-step sequencer built in. This sequencer has three different lanes that can be run simultaneously: pitch, slide, and motion; this is perfect for 303 acid-style sequences. Additionally, it has patch memory, which is something the MS-20 does not have.

Overall, the Monologue is a synth with a much more modern sound and feature set than the MS-20 Mini. That being said, because it lacks a patch bay this synth is unable to do any of the deep modulation and sound design that the MS is capable of. Although they may seem similar on paper, these two synths are quite different in their overall character and as such are suited to very different tasks and audiences. It is significantly more affordable than the MS-20, pricing in at $299 USD.

If you’re having trouble choosing between these synths, rest assured that you aren’t the only one. Here is a thread from Reddit’s synthesizers sub-forum with some comparison between these two synthesizers and some other similar options.

Check out our Korg Monologue review here!

Moog Sub Phatty

The Moog Sub Phatty is one of the most affordable synthesizers offered by Moog, a company hailed for their amazing sound and build quality. While they are both subtractive analog monophonic synthesizers, the core sound of the Sub Phatty and MS-20 Mini couldn’t be farther apart.

The Moog is smooth, creamy, and brassy while the Korg is cold, gritty, and aggressive. They both sound great for sure, but have a completely different character and are best utilized in quite different styles of music.

The core features of the Sub Phatty don’t seem so different from the MS-20. It has two oscillators which feature continuously-variable waveform selectors, meaning each wave crossfades smoothly into the next. Both oscillators have the same waveform options: triangle, saw, square, and pulse.

Although it doesn’t have a dedicated pulse width control, the space between the square and pulse waves on the waveform potentiometer can be used as a replacement for this. It doesn’t have a ring modulator like the MS-20, but makes up for this with a hard sync setting. In addition to the two oscillators, the Moog features dedicated sub oscillator and white noise in the mixer section.

The Moog does not have dual high-pass/low-pass filters like the Korg; instead it features the iconic Moog ladder filter. This, especially when paired with the multidrive control, has a completely different sound to that of the MS-20 filters. After the filter, it has two envelopes; a dedicated amp envelope and a dedicated filter envelope.

These envelopes unfortunately can not be routed elsewhere. It also has a single LFO, which is arguably a bit more versatile than the one on the MS-20. The waveforms available on this LFO are: triangle, square, ramp up, ramp down, random, and a mirror of the filter envelope shape. This can be routed to modulate any combination of the following: oscillator pitch (either both oscillators or just oscillator two), filter cutoff frequency, and the waveform selector.

On paper, the Moog Sub Phatty might seem to be very similar to the MS-20. However, when you have a listen it is clear that their sounds are very different from each other. One key feature that the MS has over the Moog is the patch bay, which gives it a ton more sound design depth. Alternatively, the Sub Phatty has patch memory while the Korg does not. Finally, the Sub Phatty is a bit more expensive than the MS-20, at $599 USD.

If you’re looking for more information on the differences between these two synthesizers, here is some discussion on that topic on the Gearslutz forums.

Korg MS-20 (Original)

When reviewing the MS-20 Mini, it seems obvious to compare it to the original MS-20, which it is trying to emulate. While it is a very good recreation of the original, the Mini is certainly not 100% the same, both in terms of sound and physical interface.

The sound differences are definitely subtle, but some people who have owned both have stated that the Mini lacks some of the iconic character of sound that the original was so beloved for. It definitely gets close, but the original goes even further in the direction of overall fatness, warmth, and grittiness. Additionally, the MS-20 Mini has the infamous noise floor issue, which I discussed a bit further above.

The obvious differences between these two synths are physical; the size and build quality. The original is quite a bit bigger, with full size keys and sturdy, quarter-inch patch points. Depending on your uses and needs, this can be either an advantage or a disadvantage over the smaller, more portable Mini.

However, it can’t be denied that the knobs and patch bay on the Mini are decidedly flimsy when compared to the original, which is built like a tank. That being said, it offers some modern features not found on the original, namely USB and MIDI connections. Finally, the most important thing is that the original is obviously going to be harder to come by, especially in excellent condition, and will end up being significantly more expensive than buying a new Mini.

If you would like to see some more direct comparisons to the original, here is an article from CDM with a side-by-side look at both synths.

Korg MS-20M

Around the time that the MS-20 Mini was released, Korg also released a limited edition module kit for the MS-20. This MS-20M was the full size of the original, but was missing a keyboard and required you to assemble it yourself. However, it had a couple of very significant improvements over both the original and the Mini.

It featured added oscillator hard sync and FM switches, and a PWM input on the patch bay for pulse width modulation. In addition to that, it gave you the option to switch between both filter revision types from the original MS-20 models.

Another huge addition is that this version supports both Hz/Volt and Volt/Octave control voltage inputs. It is no longer available for purchase, but if you can find one on the used market it is definitely the definitive version of the MS-20, if you don’t require a keyboard to be attached.

Behringer K-20

Recently, Behringer have announced that they are making also making a clone of the MS-20, called the K-20. This synth will likely come in at a much more affordable price point than the Mini, based on Behringer’s track record with synth releases lately.

However, it is only a module and therefore doesn’t have a keyboard attached. Also, there hasn’t yet been a proper sound comparison made between the K-20 and a real MS-20, so it is not yet known if it will be as faithful of a recreation as the MS-20 Mini

Pros & Cons

Pros:

Iconic, classic synth in a good form factor and reasonable price
Knob-per-function interface with no confusing menu diving or shift functions
Dual HP/LP filters means a lot more tone shaping than a single filter
Ring modulator allows you to make much more interesting sounds than just using traditional waveforms
Patch bay gives you a ton of modulation possibilities and the ability to integrate with other modular synthesizers
External signal processor and input lets you run other instruments through this synth’s amp and filter
MIDI DIN and MIDI over USB connections

Cons:

No digital features like patch memory or MIDI control of parameters
Slim keyboard might make performance difficult if you’re used to full size keys
Control voltage inputs are Hz/Volt, not Volt/Octave
High noise floor
Build quality leaves a bit to be desired
Has some surprising limitations due to its old school architecture
Monophonic nature means you can only play one note at a time
Audio output is on a mini jack

In closing, even though there are a ton of great analog synthesizers on the market these days, the Korg MS-20 is still a great choice for a number of reasons, even with the $459 USD price tag. The MS-20 is acclaimed as being one of the best analog synthesizers of all time, with a unique sound a feature set, and this is one of the best ways you can get ahold of something like it in today’s market.

This article was written by Digital Piano Review Guide contributor Nicholas Barra.

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