Gamechanger Audio Motor Synth MkII

Gamechanger Audio’s Motor Synth MkII updates the company’s idiosyncratic approach to synthesis...

In 1681 Robert Hooke presented a device to the Royal Society that used a toothed wheel to produce tones of a known frequency. There have been plenty of devices since that have used rotating discs to produce audio, but the high speed, small size and precise control of Gamechanger Audio’s motors have led to a compact device that can easily fit on a desk. No need to split it in half like a Hammond B3, and notably more portable than Thaddeus Cahill’s 200‑ton Telharmonium.

Rather than serrated tonewheels, however, the Motor Synth primarily uses light to generate a selection of wave shapes. An infrared beam is shone onto a pattern printed on the underside of each rotating disc, and the reflection is read by a sensor. There is also an electromagnetic sensor placed near each motor for an additional wave shape.

Without going into an extended history of optical synthesis, it might be worth mentioning the Vako Orchestron (as used on Kraftwerk’s ‘Radio‑Activity’), Edwin Welte’s Light‑Tone organ, Daphne Oram’s Oramics system, and of course Yevgeny Murzin’s magnificent ANS machine. These all use a graphical element that creates audio by modulating light, a technology found in early naval communication and cinema film sound.

The optical discs rotated by the motors......are ‘read’ by sensors on the board beneath.On the underside of each disc there are three graphically printed waves: sine, square and saw (descending ramp). These are represented by a varying density of ink changing the amount of light reflected, rather than a geometrically drawn wave. The patterns on the top sides of the discs don’t generate any audio, but the strobed light within the casing creates pleasing visual feedback in the same manner as the dots on the edge of a turntable. The effect is particularly satisfying when a subtle pitch modulation causes the pattern to drift back and forth.

The Motor Synth MkII has eight brushless DC motors in total, with four assigned to each voice. As well as two motor voices with four‑note polyphony, there is a DCO (new for the MkII) that can be added to the mix. The DCO is configured mostly via the two encoders under the screen, and includes a noise source, hard sync to the motors, and some novel wavefolding capabilities.

Note that the VCAs and envelope generators are polyphonic, but the filter is paraphonic, ie. it re‑triggers for all notes played within each of the three voices. There is an analogue filter for each motor voice, and a digital filter for the DCO.

Features

Downstream from the signal path of these oscillators are the mixer, VCAs, multimode filters and drive effect. Parameters can be manipulated by a number of modulation sources, and there is a built‑in sequencer and arpeggiator. Note that if the knob doesn’t have an indicator stripe then it’s a push‑button encoder — operation becomes a lot easier as soon as you realise this!

Of particular interest is the ‘clutch’ feature. This is a wonderfully intuitive concept that’s great fun when performing. Hold the clutch button and make changes to the filter and modulation knobs, etc, and then release to drop in all the changes at once. This works well when jamming along with a drum machine.

A keypad comprised of eight push buttons allows notes to be played as soon as the synth is switched on. This is useful for previewing sounds, although you’ll presumably want to connect a more comprehensive MIDI controller as soon as you can. The keypad is a good addition to get started quickly, and to keep the unit self‑contained.

The keypad is also used for the built‑in step sequencer, with the illuminated buttons lighting up as you might expect. The sequencer definitely rewards exploration, with control of some interesting parameters including glide, ratcheting, probability and the ability to repeat steps. It doesn’t take much effort to add interesting variation to a looping sequence. There’s also a terrific multi‑channel ‘motion record’ feature that allows knob movement to be recorded, but also played back at different speeds and in different directions.

One slight restriction is that there is only one knob for all of the sections of each envelope generator. This might be due to the fact there are a number of different types of envelopes: ADSR, AD, AR, DADSR, ADSHR and AD loop. So perhaps one encoder is simpler even than two, once you’re used to it. There is also a very wide range of adjustment of the shape of the envelope curves.

There is a comprehensive modulation section with three knobs for six LFOs, but it takes some serious menu‑diving to make adjustments. Even changing a simple property like LFO frequency takes some figuring out. The screen displays the various values that can be changed, but it’s not at all obvious which of the encoders or buttons correspond to adjusting the values or selecting the value to adjust. I suspect this can all be learnt over time, but re‑configuring LFOs wouldn’t be easy during a live performance.

Another useful feature is the ‘random’ button, which allows you to change up to 13 parameters at once. You can set the amount that each parameter is randomised, to keep certain aspects unchanged whilst adding variation to others. Ignore the review online that claims that the synth can generate ‘ransom notes’ — this is likely a typo, but if you do want to see your cat again contact Gamechanger Audio.

In addition to pressing the randomise button and listening to the results, exploring the selection of presets is a good way of getting to know what type of sounds the synth can make.

Hold the Alt key and press the right‑hand encoder under the screen and you’ll be treated to a selection of options for processing signals fed into the input jack on the rear. The vocoder is surprisingly good, with clear sibilance and plenty of control over details such as the bandwidth of the channels. After pretending to be a robot for a while, a lot of fun was had by connecting a TR‑606 drum machine to the input. The Latch button is useful for keeping the oscillators on while experimenting with the vocoder.

The envelope follower works well, with adjustable parameters to fine‑tune ducking effects. This mode can also be used to accept a trigger/clock input for the arpeggiator or sequencer.

This input section also allows access to routing settings for the send/return mini‑jacks, and allows the three CV and three trigger mini‑jack inputs to be linked to the parameters of your choice (similar to the modulation assign setup). It didn’t take long to connect a CV input to a modular synth and link it to the filter cutoff. A CV range between ‑10V to +10V is accepted, and it’s possible to attenuate and invert each individual input.

On the rear panel we find a pair of MIDI I/O ports, a USB B port, a socket for the external 24V power supply, three trigger inputs and three CV inputs, a pair of send/return sockets, a headphone out and an audio output and input.

Some Notes On The Hardware

There seems to be a lot of discussion about the durability of the motors in this electro‑mechanical device. As Gamechanger Audio mention, the motors are driving a far lighter load than they have been designed for, and they are operating in an enclosed weatherproof environment. I suspect that this device will remain switched off when not in use due to the noise it creates when not on standby, and so in reality the motors themselves should have a long lifetime. If it came to it, in many decades the bearings could potentially be replaced, or the copper coils rewound as necessary, assuming we can still find copper in the post‑apocalyptic era.

There has also been discussion about the seemingly high price. I suspect the price is high because this is a difficult object to manufacture! It has eight motors that have to be driven reliably with extreme precision. If you’re concerned about the price of a complex motorised synthesizer, perhaps consider buying an ocarina instead.

The build quality of this synth is simply superb. It’s a pleasantly weighty machine with a high‑quality steel casing, has satisfyingly robust knobs and buttons, and generally has an exquisite attention to detail. The discs are fitted to the motors with anodised red nyloc nuts, and the colour scheme even continues out of view inside the casing with red and silver components. It really is a work of art.

In Use

Let’s get this bit over with quickly: the Motor Synth is noisy. On powering up you are greeted by the whizzing of eight high‑speed motors, joined shortly by a fan. The motors are closely related to those found in drones, and they sound similar, although quieter due to the lack of propellers. There is a ‘sleep’ switch (new for the MkII) if you need to give your ears a break, although this only applies to the motors and not the fan. Judging by the warm air ejected from the vent on the right‑hand side of the casing it’s obviously necessary to prevent overheating.

How noisy exactly? The following values were measured with a fairly cheap handheld sound level meter: 76.5dB 100mm from rear of unit, 72.5dB 100mm vertically above the top window, 80.0dB 100mm from RH side of casing (not directly in the fan airflow). An obvious solution is to use headphones or turn up your monitor speakers, but the white noise from the fan is a bit like trying to concentrate while someone is boiling a kettle in the same room.

It seems very unfair, however, to complain of the Motor Synth sounding like motors. To paraphrase Quentin Tarantino: “If you don’t like the Motor Synth MkII, go see a different movie.”

A second noise issue is potentially more of a problem. Gamechanger Audio mention that the “inherent imperfections in the mechanical system” lead to an interesting analogue sound, but one of the imperfections seems to be an often present raspy distortion. This can be heard distinctly around 2 minutes 16 seconds into the manufacturer’s ‘MOTOR Synth MKII — Features Overview’ video (www.youtube.com/watch?v=BDDR_Pi53OU&t=136s). This distortion isn’t present on the DCO voice, and again it feels unfair to describe what may be the character of the synth as in any way problematic. Check out the video and decide for yourself. The VCS3, for example, is much loved for its imperfections.

Many synthesizers start with oscillators that have been designed with geometric perfection in mind, and so it’s exciting to find a synth built on different foundations.

Many synthesizers start with oscillators that have been designed with geometric perfection in mind, and so it’s exciting to find a synth built on different foundations. Even the DCO has deliberately non‑standard wave shapes, helping it to avoid sounding generic. Coupled with the charismatic filter this does allow fabulous sounds to be produced.

As an aside I wonder how much of the “inherent imperfections in the mechanical system” are in fact due to the print resolution on the discs. I did partially dismantle the synth to investigate, but I would also like to try printing some custom discs at some point and listening to the results. Looking at the analogue waves through an oscilloscope we can see that the sine wave is very triangular, the square wave is rounded and has sloped edges, with the ramp wave being the most accurate. Although an external oscilloscope was used for the purposes of this article, you can in fact see a trace of the wave shapes on the synth’s home screen view.

The Motor Synth’s waveforms are not like other waveforms. Clockwise from top left: sine, saw, square, and the waveform created by the electromagnetic sensor accompanying each motor.

While the wave shapes themselves have idiosyncrasies, the oscillator pitches are remarkably precise and stable. The motors hold their speed perfectly, even when the unit is lifted and shook, so no Keith Emerson style organ rocking antics. If you do want to add some Boards Of Canada‑type tuning drift, there is a dedicated knob to do just that. There is also a cross‑modulation knob that works between the two motor voices.

The motor pitch change response is fast, a point easily demonstrated by fast sequences and arpeggios, although a characteristic property of the synth is a subtle glide between notes here and there. This manifests in an interesting way, as a little chirp that has a tendency to appear between a jump in notes the first time they’re played, but then not when the same two notes are played again. It’s as if the motor note priority algorithm learns from what you might be playing and then adjusts to compensate. This is a nice property and one of the little details that give the Motor Synth its character. The fast response is helped by the relatively low load/inertia of the lightweight discs.

The motor pitch change response can be increased by adjusting the Acceleration and Brake controls. This is effectively a mechanical pitch envelope. It’s good to see the designers imaginatively playing with the properties of the motors.

A final observation is that the graphical elements on the screen have often been designed thoughtfully. Each pixel on the relatively low‑resolution grid has been positioned with care, and there are a number of clever visual cues which help you to navigate the synth. For example, adjust the master tune for the keypad and the note values displayed on the screen glide up or down in a satisfying manner.

Conclusion

So the big question: is it worth manufacturing a synth that uses motors as oscillators? Are there not easier ways of achieving the same thing? Well, there are other ways of generating sound waves, but this is simply a different way of doing so, and it’s admirable that Gamechanger Audio have tried something new.

The fun of seeing the motors through the two windows makes you want to switch it on and start making sounds, and so whether or not the motors are the most efficient way of doing what they do is irrelevant — it’s more about the inspiration of interacting with an exciting noise‑making device that’s unlike a lot of other equipment. It’s likely not the first synth someone will buy, but it is certainly an interesting one. Well done Gamechanger for making something different!

Information

£2850 including VAT.

www.gamechangeraudio.com

$3299

www.gamechangeraudio.com

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