You can understand my scepticism upon learning of the SED‑CSM from Berlin’s Rides In The Storm. A full analogue synth voice, with its own mixer, packed into a big‑but‑really‑very‑small 36HP, it’s the kind of module one might consider for their very first Eurorack purchase, sitting comfortably alongside the likes of Intellijel’s Atlantix, Verbos Electronics’ Sawtooth Stack or Black Corporation’s ISE‑NIN in terms of functionality. Only, those three retail at around £679$699, £799$1069 and £1022$999 respectively. The SED‑CSM? A tidy £465$649, or thereabouts. Too good to be true?
It’s worth me saying that, if you aren’t familiar with RITS as a developer, the output of Uwe George Giegler’s company strikes me as somehow very impulsive, in the most respectable way. I dare say there’s something very punk at the heart of RITS output. It’s this level of impulsiveness that I’m sure led to the SED‑CSM. It has controls and functions flung onto it with abandon, a manual which amounts to little more than a diagram of what each control is (it’s written on the panel already) and with scanned‑in handwritten annotations on setting the rear jumper switches. Fantastic. But immediately upon mounting it into my rack I could see that Giegler isn’t messing around. For a start, the build quality is lovely. The panel is chockablock with functions to the point of feeling quite congested, but fair to say everything here still manages to feel solidly mounted and firm, with all knobs, sliders and buttons comprising quality tactile components. And besides, a panel feeling like it has ‘too many functions’ is, in the scheme of things, not a bad problem to have.
As for those constituents of the SED‑CSM’s panel themselves, many are usual suspects when it comes to a subtractive synth voice, but there are more than a few curveballs here to separate it from the crowd — most notably, in my view, when it comes to movement. The two oscillators each offer pulse, saw and triangle waves, with wavefolding on offer for VCO 2’s triangle. There’s also generous capacity for sub oscillation with variable waveforms and XOR ring modulation available, attenuated via the cute onboard mixer, along with white noise. There are two ADSR envelopes, two LFOs and a 24dB/octave low‑pass filter. Of course, one expects CV inputs for a raft of functions on a module like this, and I wasn’t disappointed here — particularly since each oscillator has its own jack for 1V/octave pitching and a Reset input, and each envelope has its own trigger outputs to mark its attack and decay stages.
It follows that re‑routing various signals about the place with internal patching is always on the cards, but of course with a full synth voice like this, internal, patchless functionality is just as important. There’s a generous slab of harmonic texture on offer right away here, but the SED‑CSM goes further with things like variable modulation of VCO 2’s wavefolding — either manually, with an LFO or with an envelope — and the capacity to modulate both oscillators’ frequencies independently with each of the two envelopes, both of them together with LFO 2, or a combination of these. There’s a Sync button, variable pulse width for each oscillator, and also a Gravity button to change the behaviour of the sub‑oscillators (as far as I can tell, by dropping its octave, but it sounds like there’s also some sync going on — as you may imagine, this isn’t made clear in the manual). I’m always happy to see the trans‑coast pairing of wavefolding and filtering, particularly a filter that can be driven, as is the case here. While the SED‑CSM’s filter is certainly on the characterful side when it comes to analogue variability and squealing self‑oscillation, it’s nonetheless substantial and smooth, and the Drive button is a welcome addition for squeezing more tone out of it if needed. The combination of wavefolding, drivable filtering, a ring modulator and noise makes for a fantastically aggressive synth voice if that’s what you desire.
There’s also something of a secret oscillation weapon up the sleeve of the SED‑CSM, which is that it’s possible to engage 1V/octave tracking on both of its LFOs. This might look like expressive vibrato that moves in response to the note played, or — in the case of LFO 2 — audio‑rate modulation that becomes a de facto third oscillator for some Minimoog‑style massiveness. LFO 2 can switch between (shape‑variable) triangle, pulse or random voltages, meaning that it can take on various tonal characters of its own or indeed assume noise duties alongside the conventional noise generator.
In addition is a manual envelope trigger button — always handy for quick referencing when sound‑sculpting — alongside another West Coast‑inspired option, which is for either or both envelopes to cycle. This can of course mean that they take on LFO‑like roles; so pulling in an external envelope to take care of conventional functions, I could access a total of four asynchronous LFOs all churning away together, which I’d consider generous on a standalone synth of double the SED‑CSM’s size!
Every now and again a developer comes along with a design that bucks that trend, presenting buckets of character that won’t break the bank.
Eurorack has long had a reputation for being untenably expensive for many, but every now and again a developer comes along with a design that bucks that trend, presenting buckets of character that won’t break the bank. Its idiosyncrasies might take a little getting used to for some, but the SED‑CSM is an excellent example of this, suited both to existing users looking for a highly flexible standalone voice, or to newcomers looking for a vital point of access that will perform marvellously by itself, right out of the box.