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Polyend/Dreadbox Medusa

Synthesizer & Sequencer
By Paul Nagle

Polyend/Dreadbox Medusa

The Medusa combines analogue and digital, synthesizer and sequencer — and even throws in a controller for good measure.

The driver behind any collaboration must surely be to play to the strengths of those involved. In today's example this means a blend of Polyend's digital technology with the analogue skills of Dreadbox. I was already acquainted with the latter, having previously enthused over the Erebus synth, so I was keen to discover what Polyend brought to the table — literally in this case, since the Medusa is a tabletop synth, sequencer and controller rolled into one.

The synth engine features six oscillators (three analogue, three digital), an analogue filter, five LFOs and five envelopes, while the sequencer boasts up to 64 steps of notes and synth parameters. There are three voice modes, one of which is a sort of 'paraphonic plus' where chords of up to six notes can be played and sequenced. And as a final bonus, the pads can be put to general controller duties with a DAW or other synths.

Legend tells us that Medusa is associated with being turned to stone. Personally, I was keen to discover how it coped when associated with a stoner...


The Medusa is a thoroughly black and white experience, its low profile metal box sporting an 8x8 pad matrix, two neat and petite OLED displays and a number of buttons, knobs and sliders. Operationally, it's a game of two halves with a minimal transport and menu section sitting between the pads and synth controls.

Generally the knobs and sliders feel OK, although the knobs wobble slightly. The audio connectors are more solidly held in place and consist of a single audio output, an input (for processing audio via the analogue filter) and a phones socket — all on quarter‑inch jacks. The round white buttons aren't the snappiest or most responsive though; occasionally I hit Play on the sequencer but the Medusa completely failed to notice.

Having a layout with the pads on the left-hand side and the synth controls on the right felt slightly contrary to me as a right-hander. The small silicone pads have a pleasant squishiness and each one generates data in the X plane (pitch bend, side‑to‑side), Y plane (mod wheel, up and down) and Z (channel aftertouch, pad pressure). A recent firmware update also added velocity to the list of attributes transmitted from the pads in its controller guise. With a generous choice of scales and pad layouts, Medusa is therefore a performance surface that will take time to fully appreciate.

MIDI is supplied via regular five-pin connections or USB, with the latter also used for firmware updates and patch dumps. Power is from an external 15V adaptor and the power-up sequence includes a calibration routine for the analogue oscillators, after which you're good to go.

Hybrid High Jinks

Polyend have crammed quite a lot of synthesizer into an area measuring just 227 x 170mm. Inevitably, this has been achieved by sharing controls and by tricks such as using single buttons to step through values. At any time, you can edit either trio of analogue or digital oscillators — a 'Digital' button lights to indicate when the latter are live on the controls.

Regardless of type, every oscillator has four standard waveforms (sawtooth, square, triangle and sine) and three choices for octave shifting. You can squeeze a further octave up or down from the Tune knob, a control that switches from semitones to fine tune at the press of the appropriate button.

You quickly realise that a number of the controls are 'analogue only'. For example, the PW knob changes the pulse width of the analogue square waves and the two Sync buttons synchronise analogue oscillators 2 and 3 to the first. The same limitation applies to the FM knob. Oscillator 3 serves as a modulation source for 1 and 2 and the filter cutoff frequency, the knob's action tied to a pair of selection buttons. This is exponential FM and therefore a source of clangorous cross modulation, ripping filter noises and typically edgy material rather than the more refined linear FM.

The oscillators are further supplemented by a versatile noise generator with a built-in filter that morphs the noise colour from brown through to violet — or deep and boomy to high and hissy, if you prefer. All seven audio sources are blended in the mixer, along with any external input signal (for which no on-board attenuation is provided).

Lacking oscillator sync, PWM or cross-mod, it might look like the digital oscillators have been left behind. Fortunately, the Wavetable knob offers a clue to something extra lurking beneath the covers to redress the balance. To explore further, you must select wavetable playback by stepping through the regular waveforms until all four waveform LEDs light up.

The Medusa possesses 20 wavetables, each with 30 waveforms. Browsing the available tables involves the menu system, entered by a press of the unlabelled encoder in the middle. Turning the encoder scrolls through various options and the last of these is Wavetables. Right now it's just a list of numbers, which isn't terribly helpful, but Polyend say there may be alternative tables in the future, along with the possibility of names.

Auditioning each in turn, I found the first wavetable to be packed with glitchy transitions, the fifth is vocal in nature, several are organ-like and some feature smoothly morphing synth waveforms. While it's not the most comprehensive wavetable implementation out there, it's a welcome addition for fleshing out the Medusa's sonic range.

The Wavetable knob selects the wave within the current wavetable and, as a bonus, the right‑hand OLED supplies a graphical waveform view. Naturally I wanted to try automatically sweeping through the table or giving each digital oscillator its own wave, which required digging into the Medusa's modulation system.


Modulation is a straightforward affair in which a single source, either an envelope or LFO, is aimed at a single destination. The source is selected by button, at which point dedicated Amount and Target controls come into play. There's also a shortcut method of allocating the target, by holding a source button and moving one of the panel controls (or, in the case of FM, pressing one of the FM buttons). With the exception of the envelope stages, most of what you'd expect to modulate is up for grabs — including LFO waveforms, rates and amounts. Once you grasp the concept, it's therefore easy to set up modulation of the pulse width, a sweep through the wavetable or a whoosh of noise. When you aren't tweaking controls, the default state for the right‑hand OLED is to dynamically represent the movement of all 10 modulation sources.

It's worth noting that PWM applies to all analogue oscillators with a square wave selected, but you are able to modulate the position in the wavetable independently for each digital oscillator. In doing so, there are a couple of operational idiosyncrasies to grasp. First, and rather annoyingly, the target list is obscured by a box saying 'OFF' until you activate the LFO or envelope by double-clicking its button. Secondly, there's no visibility of the modulation source that's currently live on the controls. Only after you move an envelope slider or LFO knob does the relevant button flash, which seems needlessly obtuse.

The envelopes have an initial delay stage and a Loop button. And while the envelope only loops during 'note on' it's still a great bonus, especially if you start running out of LFOs. LFO speed is displayed in Hz (yay!), in the range from 0.01Hz to 30Hz. When synchronised to the current tempo, the values switch to note values, from six through to 1/64.

Granted, the method of 'single source to single destination' is no substitute for a full modulation matrix, but it scores by being fast and uncomplicated. The LFOs have an extra trick up their sleeves too: fully morphable waveforms from sine through to sawtooth, taking in square and triangle on the way. The only omission is a random (S&H) source.

Analogue Filter

The Dreadbox analogue filter offers three modes: low-pass 12dB, low-pass 24dB or a high-pass 6dB slope. Successive firmware updates have gradually shunted the loud and ugly resonant squeal towards the very end of the knob's travel, although it's still lying in wait for the unwary. (When scrolling through modulation targets, you quickly learn to keep the modulation amount low to avoid the speaker-shredding peak as you pass resonance in the list.)

While the filter isn't quite so fluffy and sweet as the Erebus', it's a splendid way to add warm squelch and fuzziness to the analogue and digital waves. The high-pass filter is an underwhelming but necessary tool for thinning out the super-thick textures that half a dozen sometimes detuned oscillators can produce. As you'd expect, the note tracking knob allows high notes to be brighter.

The synth engine's final cog is found in the small Play Mode section and offers glide plus three voice modes. In the first of these, Mono, all six oscillators are stacked to deliver some of the Medusa's most obese solo and bass sounds — or delicate, shifting layers if you've chosen to modulate the oscillator levels. The next voice mode is P1, which invokes three voice paraphony, each voice having a layered digital and analogue oscillator. Lastly, P2 allocates the oscillators as six separate voices, each with its own amplitude envelope. The proviso is that they are still all positioned before the single filter.

Digging into the Config menu to specify a Voice Priority of 'Next' tells the Medusa to play each oscillator on a round‑robin basis. If you then open the filter fully you can achieve pretty credible six‑note pads and chords. Combining this mode with the oscillators set to different waveforms is a superb way to demonstrate that paraphony isn't necessarily inferior to regular polyphony, just different.

Finally, if you're ever stuck for inspiration, Polyend fitted a Random button to randomise synth and grid parameters.

The Medusa's front panel. Around the back are MIDI in, out and thru ports, a USB port and quarter-inch jack sockets for audio out, headphone out and audio input.The Medusa's front panel. Around the back are MIDI in, out and thru ports, a USB port and quarter-inch jack sockets for audio out, headphone out and audio input.

Pads, Modes & Performance

Up to 128 patches can be stored in two banks (A and B), with each patch comprising patch, sequence and grid data. The latter consists of up to 64 pads' worth of parameter modifications. Patches aren't named but selected using the Load button in conjunction with the pads. A nearby hold button is used to drone the last triggered note (or chord) at the current sustain level.

Operationally, the pads are used in two distinct ways: Notes mode or Grid mode. In the former, the pads trigger notes and transmit control values based on finger position and pad pressure. Since the pads are quite small, I found it a challenge to play with any great precision or smoothness. And sometimes my touch was simply too light for every hit to register, especially when playing left handed.

In Grid mode (the Grid button is lit), each pad replays any data stored in it, with the type of data shown by various brightness levels — more about this later. For now we'll remain in Notes mode, where a number of squares are lit to indicate the root notes within the current scale.

To see the root and scale values, you need to enter the menu system — a list of top‑level menus for defining pad behaviour, sequencer settings, etc. Spinning through until you reach the Scale entry, you're able to choose from an impressive 40 scales and modes, covering the familiar and the exotic, eg. Marva, Hirajoshi, Iwato, Yo and Enigmatic. Although there's no user scale option, I reckon it'll be quite some time before you work your way through the ones on offer. Pad layouts and root notes are selected in the same manner.

Layouts are numbered from 1-8, followed by 'Guitar', which sets out the notes in a way not unlike a guitar fretboard. As you audition each, the pad display shifts to indicate the new position of root notes.

Playing a synth from pads is obviously a very different experience to playing a keyboard, but once you get past the unfamiliarity, fresh phrases caused by new finger positions should soon burst forth to surprise and maybe delight. Oddly enough, this was when I most missed the ability to name patches as that could have helped me remember the key and scale used in each.

Also within the menu system are the assignments for pitch bend, mod wheel and aftertouch (X, Y and Z) with targets already familiar from the modulation section. You could therefore wiggle your finger left and right to bend pitch, push it upwards to open the filter and apply pressure to increase volume — and the allocations you prefer may be saved on a per patch basis.

In another menu — Config — you assign the MIDI channels, synchronisation and so on. For its controller roles, you can choose whether the Medusa sends its data via five-pin MIDI or USB. It even supports MPE — polyphonic expression for those devices that support it (sadly I didn't have one to try).

Via a special mode you can address the six oscillators independently via a (fixed) selection of MIDI channels. This acts like a kind of 'multitimbral lite' mode when controlled by an external sequencer. Sadly you can't capture these multi-channel sojourns into the Medusa's own sequencer though.

Other parameters here include setting whether panel tweaks should take place instantly or only when the knob or slider passes through the stored value. Calibration is there too, and from time to time you'll need to perform this manually since the analogue oscillators occasionally drift. This is more noticeable when stacked with the digital oscillators and may even be considered a feature by the perverse. The Medusa doesn't feature a master tune, although hopefully this may be added in the future.


As far as the sequencer is concerned, the operational modes again play distinctly different roles. Notes mode is firmly designated for the recording of notes and chords, which are replayed using the values of the current patch. Any X, Y and Z performance data you happen to play at the time is ignored, as is velocity (all notes are stored at maximum velocity). I suppose this makes some kind of sense as the synth engine doesn't respond to velocity, but it limits the possibilities for sequencing external gear.

When in Grid mode, the sequencer triggers stored notes plus Patch Modifying data — a similar concept to Elektron's Parameter Locks. This PM data can be recorded freely during playback or by selecting a step (or steps) into which parameters should be captured, or cleared from. There seems no limit to the amount of parameter tweaks held, although sadly there's no way to see what they are prior to a clearing operation. Instead, Polyend employ varying degrees of brightness to show whether a step contains no data, note data, PM data or note plus PM data. However, the different levels aren't always easy to distinguish and there's no avoiding the thought that coloured pads would have made life much easier.

In use, the sequencer is simple if slightly menu-bound. You have to enter the menu to set the tempo and swing values but you also need to go in every time you want to change the pattern length (1-64 steps) and direction (Forward, Backward, Pingpong and Random). If those are the kind of things you'd typically expect to do live, it feels somewhat awkward. The sequencer runs at a fixed 16th‑note resolution, which is, again, limiting.

As every patch holds a single sequence and there is no chaining or song mode, you quickly learn to embrace simplicity and make extensive use of Patch Modifying data to spruce things up. Fortunately, this is a source of many pleasant surprises, eg. adding fast LFO modulation on certain steps to simulate note repeats, tying specific waveforms to certain notes or simply adding envelope and noise tweaks to create percussive grooves.

Slipping back into Notes mode for a moment, you can transpose a running pattern by holding the Hold key and pressing a pad. However, switching during playback causes the sequencer to switch between honouring the PM data and ignoring it. Since this can lead to significant tonal leaps, you'll need to find a way to either avoid Notes mode or incorporate these leaps into your performance. Although you can edit notes in Grid mode, you can only record them in Notes mode — regardless of whether you're using the Medusa's own pads or an external keyboard.

If you recall a patch while a sequence is running, it switches immediately rather than at the end of the pattern. And if you save during playback, there's a rather unpleasant glitch, which kills off any hopes of developing patterns and sequences in a live situation.


Unless you're Perseus, there are multiple ways you can approach the Medusa. It could be a MIDI controller transmitting notes and performance data into a DAW environment, or perhaps a stand-alone pad-based synthesizer that breaks the usual keyboard conventions. Some will find the built-in sequencer perfectly suitable for melodies, bass lines and chords, especially given the power of Grid mode, where you can sequence what amounts to a different patch on every step if it takes your fancy.

Even if you forget the sequencer and work exclusively in Grid mode, the Medusa offers a rare degree of choice. You can prepare and trigger up to 64 notes or chords, each with specific synth settings, which can inspire genuinely different performance techniques. If you have recorded only parameters into the pads, the notes can be supplied by an external MIDI source as you introduce modifications dynamically.

By itself, the Medusa synth engine is capable of a good range of analogue and digital tones. It's ready to deliver percussion, sound effects, rip-roaring solos, snappy basses and even pads. It's aided considerably by the various voicing modes, the six notes of paraphony and the Dreadbox filter.

At the price, it might struggle to make a huge impact unless its quirky feature set appeals. Each firmware update has brought the Medusa closer to completion and more are scheduled. It would be nice if Polyend addressed the general matters of visibility and accessibility, the lack of names for patches and wavetables, the under-developed MIDI spec and inability to dump and restore patches in SysEx format. Then again, it might already tick enough boxes for some; it's certainly a fresh take on the concept of synth, sequencer and controller.


There are a number of controller solutions out there, many of which are aimed at your DAW rather than stand-alone use. If a pad controller isn't essential, a number of variations on the synth/sequencer theme come to mind. The most colourful might be the compact and powerful Synthstrom Deluge, a multitimbral synth, sampler and sequencer with built-in effects and up to 64‑note polyphony.

Firmware & MIDI

I worked my way through a number of firmware revisions before starting this review. Version 1.1 added a means of updating the firmware and dumping/restoring banks of patches via a dedicated app, MedusaTool. I was unable to get this working on my Mac (it has quite an old OS) and on my Windows 10 laptop, the app obstinately remained as a tiny box despite my best efforts. However, since Polyend have not provided any means of dumping patches and banks via regular SysEx, it's important to stick with it. (Maybe I'm unusual in having a store of patches in SysEx format dating back to the 1980s, but I can report these still load painlessly into synths today. I doubt this would be the case if I required bespoke software from the time!)

The MIDI spec currently feels incomplete and slightly idiosyncratic. I've mentioned in the review text that velocity is ignored by the synth engine, but some of the standard MIDI CCs have been oddly allocated too. The most significant of these is CC7 (volume), which has been hijacked for oscillator 1 tuning! The Medusa doesn't respond to MIDI Program Changes either, so patch selection is always a manual affair.



  • A versatile blend of analogue and digital synthesis.
  • Paraphonic, capable of up to six-note chords.
  • A different type of synth playing surface.
  • Grid storage of parameter modifications is wonderful.
  • Step sequencer includes parameter recording.
  • Solidly made.


  • The sequencer is basic and rather menu-bound.
  • The pads are small and not the most responsive.
  • MIDI spec could be improved.
  • Some aspects feel unpolished; the divide of duties between Notes and Grid modes feels awkward.
  • Shared controls, so less immediate than it might be.


The Medusa is a powerful and often subtle hybrid synth whose killer feature is the ability to store up to 64 complete sets of parameter tweaks in every patch. Also acts as a control surface and sequencer.


£879 including VAT.

Published April 2019