Introduction

The Redshift 6 is a digitally controlled six-voice, two-oscillator analog polysynth. It is Finnish manufacturer Supercritical Synthesizer’s first foray into polyphony and fixed architecture synthesis, drawing from  the technology behind their prior Demon Core Oscillator and Neutron Flux Filter Eurorack modules.

What makes the Redshift unique from a technical perspective is that it features configurable digitally controlled analogue circuitry, meaning that it is possible to create new analog – the Redshift’s dry signal path is fully analog – oscillator and filter modes (“Engines”) through digital firmware updates.

To our knowledge, there is currently no other product in the synth world utilizing this kind of technology – although in the pro-audio space, McDSP have gone for a similar approach  in the realm of outboard saturation and compression with their "APB Analog Processing Box".

The ability to receive new analog oscillator and filter modes via firmware updates makes the Redshift’s launch somewhat unique in the field of analog synths. Accordingly, Supercritical have chosen to launch the Redshift with a solid basic foundation – a core oscillator a core filter mode – and to expand its features and capacities over time with frequent firmware updates. This review was done on the 1.1 firmware, you can find a development roadmap for the rest of 2025 and beyond here and Supercritical are actively responding to user feedback over at their Discord channel. 

Although some of the planned features like a pole morphing filter and a DCO engine focused on harmonic partials are in no doubt exciting prospects and highly novel developments in the analog domain, this is above all a review of what the Redshift 6 is right now – which, even with its current firmware version (1.2), is an innovative analog poly synth with a smooth workflow that takes analog synthesis in novel directions that were previously only possible in the digital realm.

Basic sound and first impressions

Some impressions based on early demos of the Redshift seem to have classified it as a “clean” sounding synth. And while it can certainly sound clean, that is only  really the case with certain settings – the overall sound of the Redshift is heavily influenced by multiple gain stages who’s  impact on the overall sound may not necessarily be that obvious without some hands on experience with the synth. When at its max, the Redshift can  sound downright filthy and produce levels of distortion beyond what most synths have on offer.

That said, while it certainly can pull off vintage-sounding tones, the Redshift is emphatically a modern DCO synth operating at the cutting edge of what is currently possible with analog technology, so those looking a bread and butter VCO synth will probably best served to look elsewhere.

Given Supercritical’s background in Eurorack, the closest point of comparison to the Redshift’s sound and design ethos can probably be found in contemporary analogue modular designs. And while it does not quite have the full patching flexibility of a modular system, it does has some modular-inspired tricks up its sleeve that have been rarely or never done before in an analog poly synth.

In terms of  basic applications in the studio, the Redshift excels at most common poly sounds, be it leads, stabs, pads or strings, with a basic sound that is present and powerful but also fits in a larger mix quite well.

Furthermore, with its powerful stereo voice architecture, it can also sound wide, and we mean wide!  The Redshift’s capacity to generate native stereo width without FX puts most analog synths, and even some digital ones to shame, and can easily keep up with the generally wide nature of  modern VST-driven music production — none of the sound examples below feature reverb or any other stereo FX.

Contrasting this more “modern”  side of its sound, however, the Redshift  can also sound quite lush and   “vintage” when used in a traditional mono-out configuration – stereo width is available and impressive sounding, but definitely not needed for the Redshift to be a good sounding synth. See below for an example.

With its flexible unison options and the sheer amount of filter overdrive on tap, the it can even sound quite meaty when used as a  single voice mono synth – see the examples below.

FM?

One sonic area that the Redshift does not (currently) cover is   FM and audio rate modulation timbres, as there is a lack of oscillator FM and the oscillators are not exposed as a source in the modulation matrix. While the digital LFOs do go up to audio rate, they only reach up to about 100hz, not high enough for most pitched FM timbres.

So, while you definitely can get some “techno-style” dissonance out of the oscillator tunings – see sound example below – the Redshift is probably not the right option for those primarily interested in dissonant and inharmonic timbres.

That said, even though the Redshift’s analog oscillator topology does not support true analog FM, Supercritical have stated that there may be plans to add more digital audio rate modulation and/or FM tools with future firmware updates.

Build and interface

In terms of I/O and interfacing, the Redshift comes with is one stereo main output pair and two stereo aux output pairs, for a total of six individual analog outputs, which might come in handy with the upcoming multi-timbral functionality. MIDI (including MPE) can be received both via USB and a traditional MIDI input.

The Axel Hartmann designed build of the Redshift feels  solid and sturdy, including the press-buttons and digital encoders that reliably react in the way you expect them to. The 2,7" color screen also fits  well into the rest of the design and generally feels like it enhances, rather than distracts from the overall user experience.

Despite being a fairly complex screen-based synth, the Redshift’s basic workflow is surprisingly immediate and requires basically no menu diving or use of the shift button, as the key edit panels are instantly accessible via dedicated physical buttons and the edit screen layouts are simple, logical, and usually confined to a single page.

Workflow

That said, while the Redshift’s basic operation and workflow are very easy to work with, it should be noted that in terms of the synth’s sound parameters, Supercritical have definitely gone for an approach that prioritizes power and flexibility over a more curated “all-sweetspot” design.

For example, whereas in other synths, a filter usually comes with a specific pre-defined characteristic, the Redshift’s filter essentially allows the user to precisely calibrate its response along the “clean-dirty” and “smooth-squelchy” axes according to their liking.

With such flexibility – also  in terms of the generally quite large parameter ranges on tap – there are definitely some settings that don’t all that musical, and often a bit of back-and-forth is required to land on the right combination of parameters for a satisfying result. But of course, this level of flexibility also allows the user to harness the full power of the Redshift’s synthesis engines and to craft sounds that go beyond  your typical analog sounds.

Oscillators

The Redshift’s oscillators are digitally controlled (DCO) analog oscillators that can be configured in a variety of way. The current 1.1 firmware release comes with the “Demon Core” engine based on the module of the same name. At its most basic, it features two analog DCO oscillators with saw and pulse (PWM) waveforms.

For those that prefer the liveliness of some of the more vintage DCO designs, it is worth noting that the two oscillators do audibly drift and pulse against each other even with the detune settings set to minimum, as can be heard in the clip below. The second clip features an example of the oscillators set to LFO-modulated PWM.

While these oscillators do function perfectly well as bread and butter analog DCOs when needed, what sets them apart from other designs is Supercritical’s proprietary “Demon Core” technology that allows each of the six voices to create up to 16 tunable copies of themselves.

These additional voices can be used for detuning, paraphony and multi-timbrality (forthcoming), and in addition to the oscillator-core unison with 16 oscillators per voice, there is also an additional stereo unison option in the voice panel lets you unison-stack each of the six voices, up to the almost comical amount of 96 (16 times 6) analog oscillator voices on a single note.

Since the oscillator-core detuning is one of the Redshift’s most unique features, there are two dedicated physical knobs on the front panel for spread (number of oscillator copies) and detune (amount of detuning). You can hear a quick example of the oscillator detuning in the clip below.

With the large range on both of these parameters, the Redshift can from subtle analog thickening to ensemble-chorus style lushness, to strange flanging and phasing, to completely detuned walls of sound – and of course that supersaw style sound! Since (to our knowledge) this is the first time this kind of massive voice-stack detuning has been achieved with actual analog oscillators, the Redshift offers a new and slightly different sounding analog spin on those classic “JP-style” trance leads.

Variable Character Filter

The Redshift’s base filter engine also draws from one of their previous Eurorack modules, namely the Neutron filter. Much like the Redshift’s oscillators, it also offers a spin on traditional designs through its “character” knob that switches between five different approximations of different classic filter topologies. Going beyond simple pole or resonance switching, these different character modes drastically alter the filter’s frequency, resonance and gain staging response, ranging from clean to screaming and distorted.

While there is definitely a common sound to these modes and it’s not quite like having five entirely different filter circuits in one synth, the differences between them are quite pronounced and will be more or less immediately audible on most sounds. Below is an example of a filter sweep with different character modes and a clip that rotates between the different modes, although keep in mind that this is much better demonstrated when hands-on with the synth, as the modes are highly interdependent with the other filter parameters.

Almost equally as important is the filter “drive” parameter, which is far more than simple distortion control. Each of the five modes also has a  specific and noticeably different drive sound and the amount of drive significantly affects the filter’s overall response and resonance behavior, to the point where the same mode can almost sound like two different filters with low and high drive settings.

Another interesting aspect that differentiates the Redshift’s filter drive compared to a lot of standard synth  drive and distortion knobs is that – rather than just clipping off everything in a wall of distortion like a standard overdrive – high drive values can shift into interesting waveshaping harmonics manipulation.

With some settings, the filter drive can almost sound like a West Coast style wavefolder, turning saw waves into strange, folded pulse waves in a way that would be impossible to recreate with external effects – and remember that, unlike  with standard-issue modular wavefolders, this is all done in full per-voice polyphony! Below you can hear first an example of filter drive distortion, and then an example of wavefolding-style filter drive.

Each of the five filter character modes is implemented as a fully state variable filter that can smoothly morph from highpass to bandpass to lowpass. The filter morphing (“mode”) is available  as a destination in the modulation matrix, allowing for some very interesting and less common filter sounds when modulating the filter morphing with things over than standard LFOs and envelopes. Below you can hear a clip of an SVF-style sweep.

There is also an additional character-morph parameter that can smoothly interpolate between the different character modes – and is available as a destination in the mod matrix! Modulating the character morphing is definitely a more experimental technique that doesn’t always quite work in practice, since some of the character modes have noticeably different gain staging. But anyone that’s ever dreamed of being able to morph between the sound of a classic ladder filter and a 303-style filter or a classic SVF filter and an MS-style filter on the fly will certainly have a field day with what is possible here.

As mentioned above, the interplay between all of these highly interactive filter parameters will often require a bit of juggling, but with some practice, being able to arrive at exactly the right character for a sound can be highly satisfying – if you ever feel like the sound could use “just a bit” more of something,  the Redshift’s filter almost always lets you dial in exactly the combination of characters that you desire, whether that be “drippy grittiness”, “shiny smoothness”, “squelchy liquidness” or any other combination.

Modulation

Speaking of modulation, a core part of the Redshift 6 is its very robust and flexible digital modulation matrix. Despite the power and flexibility that is on tap here it is still fast and enjoyable to use with very little menu-diving, and the edit pages for the core LFOs and envelopes each have a dedicated physical button, making it easy to quickly go back and forth when fine-tuning LFO and envelope modulations.

The only thing that has sometimes been an annoyance with the current firmware version are the very coarse modulation depth sliders that can go from subtle to OTT much too quickly – but to Supercritical’s credit, this has already been addressed in the latest firmware beta which comes with a shift-key option for much finer parameter adjustments.

The available modulation sources include four – polyphonic – individually controllable multi-waveform LFOs, four envelopes individual (DCO/amp/filter/aux), various MIDI and MPE modulators, as well as a variety of voice and note-event modulators.

As with any capable digital modulation matrix, certain modulation source parameters are available destinations, meaning that the speed of LFOs and the ADSR-contour of envelopes can themselves be modulated, allowing for the creation of complex and interactive modulation patterns.

As with everything else, the Redshift’s firmware is firmware-expandable and with the first firmware updates, Supercritical have already a number of interesting additional modulation destinations. They are also working on a “Math” page for modifiers like attenuators that could bring even modular flair to the Redshift’s architecture.

Voice modulation

As mentioned above, the Redshift’s modulation matrix features a variety of voice and note-event related modulators, which could be easily overlooked as a minor or niche feature on a first glance. But once you take into account that fact the Redshift is a fully polyphonic per-voice stereo synth with a highly advanced voice architecture – and that those voice modulators (as well as the polyphonic LFOs!) can assigned to anything on the mod matrix, it quickly emerges as one of the Redshift’s most powerful features.

For example, it is possible to assign a random voice or voice split modulator to the SVF filter’s morph control, meaning that with a chord sound, some of the chord’s voices will be played through the filter’s highpass mode and others through the filter’s lowpass or bandpass modes – a trick reminiscent of the now semi-mythical Oberheim Four and Eight voice synths that few synths have been able to replicate.

With a monophonic sequence, there could be an alternation of highpassing and lowpassing – or any other modulateable parameter – on sequential notes of a sequence somewhat reminiscent of the Mono/Poly’s famous voice round-robin mode.

Furthermore, as was mentioned earlier, the Redshift’s voice architecture is natively stereo and features a powerful voice panning mod destination that allows you to dynamically spread the  voices around the stereo field in all sorts of manners.

And since these voices can vary in not just their stereo position but also  their timbre, it becomes possible to create dense and complex stereo soundscapes from a simple sequence or chord loop, turning a single dry patch into something that almost sounds like a detailed layering of multiple different sound sources.

If there is a space in which the Redshift’s core capacities really shine on their own terms, it is perhaps this meeting of voice modulators, native stereo voice panning, filter morphing, polyphonic LFOs and unison stacking that  exceeds what even many digital synths are capable of  in this respect – and all that with a fully analog sound engine.

Closing Words

At 1.259€ retail (EU price incl. VAT), the Redshift 6 is solidly competing in the mid-range bracket of poly synths. When measured against what is often considered desirable in that market – like the presence of “vintage-sounding” VCOs and “brand name” filter topologies – as some early impressions have done, there are certainly other options that seem more favorable from this perspective.

But of course, that is not the point of this synthesizer. VCOs or not, there is no other analog poly synth at this price – or any price – that can stack 96  voices on a single note or smoothly interpolate between five different filter typology characters.

Whether that all sounds very exciting or mostly unnecessary, will perhaps above all depend on whether one sees analog as a reliable provider of classic tones or a contemporary technology that still holds potential for novel sounds. While those in the first camp might well be better off with another option, for those in the latter group, the Redshift 6 is undeniably one of the most technologically forward-pushing developments in the realm of polyphonic analog synthesis in a very long time.

All that said, the elephant in the room here is obviously that the Redshift 6 is still actively in development right now. While its firmware generally feels mature and not like a beta – there were some minor bugs in the 1.0 release that seem to have  mostly disappeared with the 1.1 version – in terms of its user experience and reliability, it is currently not quite yet feature-complete.

While none of the currently missing features really stop it from feeling like a perfectly useable poly synth, those who put a priority on things like on-board FX, internal sequencing and multi-timbral functionality might want to consult the roadmap and check back in a few months.

Finally, given the nature of the Redshift’s open architecture and development process there is of course the question of future potential. If the Redshift is already a synth toying with the boundaries of analog, the planned additional engine modes on Supercritical’s roadmap – some of whom sound downright wild – may burst them wide open.

As everyone that has spent time in the synth and music technology world, fantasy and expectation can be both be a pleasure and a detriment. Those with potential interest in the Redshift 6 will have to come to their own conclusion on what they are comfortable with. At this time, there is certainly no harm in waiting for a bit and checking back towards the end of the year, by when Supercritical are planning to have implemented most of their  current roadmap.

On the other hand, for those who don’t mind, or might even enjoy, tinkering with new features as they drop – luckily, Supercritical have made firmware updates a quick and mostly smooth process – it is worth noting that the Redshift 6 is not a product who’s sale point is forced to rely on future promises.

As it exists, right now, it is an excellent sounding synth with great build quality, a pleasant user experience and solid firmware, doing almost everything one would want from subtractive polyphonic analog synthesis while also taking into unique and novel directions.

You can find more information over at Supercritical’s website and shop the Redshift 6 over at SchneidersLaden.