Electron Sidstation

Swedish company Elektron have taken the retro philosophy to new heights, with a synth based around the original SID sound chip from the Commodore 64 home computer. Simon Trask finds out if this is inspiration or insanity...

The Commodore 64 was the first computer I owned, and I still remember it with affection — not least because it was the first micro to treat sound and music as something more than a third‑class afterthought. Its music and effects capabilities came courtesy of a specially‑designed sound chip, the MOS 6581 Sound Interface Device, colloquially known as the SID chip. SID provided nothing less than a synthesizer on a chip, complete with three oscillators, a multimode filter and three ADSR envelopes. As such it represented a major development in the sonic capability of personal computers.

The SID chip was designed for Commodore in the early eighties by Bob Yannes, who later went on to found Ensoniq and produce much more powerful synthesis chips and stand‑alone synthesizers. His original sound chip has not been forgotten, however, particularly by Swedish company Elektron — of whose new SidStation it forms the heart.

Travels With Sid

As well as the three oscillators on the SID chip itself, the SidStation offers the ability to route external audio through its multimode filter.

Elektron's motivation for developing the SidStation can be summed up in a short quote from the manual and web site: "The SID is the classic synthesizer that never had a case built around it." Well, now it has a case, and a striking example of retro‑futurist styling it is too, looking for all the world like a remnant of Flash Gordon's spaceship. In fact the SidStation is a compact and fairly light unit, though at the same time the casing feels quite robust.

While some may see the SidStation's user interface as an unwelcome return to the late '80s, Elektron have done a good job of making it as easy to navigate as possible. The bulk of navigation and editing from the front panel is done via a numeric keypad with keys from 0 to 9 and A to D, plus star and hash keys, as on a telephone. Fortunately, this isn't as bad as it sounds. The A and D buttons function as Exit and Enter buttons, the B and C buttons as value inc/dec buttons (as indicated by the adjacent up and down arrows), and the asterisk and hash buttons as left and right parameter select buttons (again as indicated by the adjacent arrows). The currently selected parameter is clearly indicated by the slowly flashing square brackets around it, and where there are more parameters than can be displayed in a single LCD page, small arrows appear in the display to let you know that you need to step horizontally to another page (there are never more than two pages linked in this way).

In Edit mode you can also use the 1‑4 buttons to directly select parameters in the 2 x 16‑character backlit LCD, while the Rotary Encoder and four Direct Controller knobs can be used to edit the selected parameter. There are some well‑thought‑out timesavers, such as the ability to quickly move to and fro between oscillators when you're editing them in Single mode, by pressing the zero button, then pressing the left or right button. In general, it's possible to move very rapidly through the SidStation's hierarchical menu system.

Though learning your way around the SidStation isn't an arduous task, it's surprising how many parameters the instrument offers you. In Patch Play mode the four Direct Controller knobs can be used for live edits on up to four SidStation Patch parameters, selected from over 80 available parameters. The knobs are also mapped to MIDI controllers 16‑19, so you can record your live edits into a MIDI sequencer for subsequent playback as part of a sequence. The selection of parameters and their value ranges are specific to each Patch, so simply by changing the Patch on playback you can have your sequenced edits controlling a completely different set of parameters. Also, each Direct Controller Knob transmits MIDI controller data whether or not a SidStation parameter is mapped to it, so you can use some or all of the knobs to control an external synth without affecting the SidStation itself.

If you prefer a more graphical approach to Patch editing, the SidStation comes up trumps with a MIDI implementation that allows all of its synthesis parameters to be edited remotely via MIDI, so it's possible for users to create graphical editing environments within MIDI sequencing packages that support such things (a Logic Environment for the SidStation is available on the unofficial web site at www.abstractreality.com/sidstation/). Rather than any tricky NRPN or SysEx parameter edits, the SidStation's MIDI implementation uses straight MIDI controllers for all its parameter edits.

The module's rear panel is equipped with MIDI In, Out and Thru sockets, a line‑level audio jack output, an external audio input jack that accepts an unbalanced line‑level signal, and a DC power input socket for the external PSU that comes supplied with the unit. Also tucked away round the back are a power on/off switch and an LCD contrast adjust knob. External audio inputs on synths are in vogue these days, of course, so the fact that this 18‑year‑old computer sound chip has this capability is a definite bonus. The implementation is nowhere near as flexible as, say, the Novation Nova's, but it does route the (line‑level only) input sound through the SID's filter section, where you can do quite a lot of modification with the multimode resonant filter and its associated envelope and LFO modulation capabilities. I found that the signal level was relatively low against the SID's own oscillator outputs, even with the external volume level whacked up. If you want to hear the filtered external sound only, the easiest and most flexible way is to trigger notes on a different MIDI channel from the SidStation's user‑assigned Basic Channel — this still activates the filter and amplifier sections and associated modulators, but not the oscillator section.

Oscillating With Sid

The SID chip has three oscillators, which can be used in one of two ways. In Single mode, the synth is monophonic, using a sound consisting of up to three layered and independently programmable oscillators. In Poly mode, you can play up to three notes at once, but each note plays only a single‑oscillator sound (using Oscillator 1's settings).

The oscillator section also has ring‑modulation and oscillator‑sync capabilities, which of course are only usable in Single mode. When you enable ring mod and/or oscillator sync for an oscillator, it modulates or syncs to the previous oscillator — so 2 syncs to 1, 1 to 3, and 3 to 2. Each oscillator offers a choice of five waveforms: triangle, sawtooth, square, mixed, or noise. With the square wave selected you can also modulate the pulse width, either setting a static value or defining two values that the SidStation will move between. In addition, you can enable PWM sync, which means that each time you play a note the pulse‑width start point is reset to its assigned value. Each oscillator's pitch can be set to Key (in which case it tracks the incoming MIDI note data) or to a fixed note value in the range C#0 to E8. You can also transpose the pitch of each oscillator +/‑ 24 semitones in semitone steps, and detune it up to +/‑ one semitone, which of course allows you to create a richer, fatter sound and adds more sonic flexibility to the oscillator‑sync and ring‑mod effects. Other pitch‑related parameters are pitch‑bend wheel range (up to +/‑24 semitones) and portamento rate, both definable per oscillator; the SidStation's portamento function takes the same length of time to slide between any two notes, like the TB303's. You can also turn legato mode on and off.

Sync'ing With Sid

Single mode also gives you access to a basic arpeggiator — in fact, although this is the monophonic mode, each oscillator has an independent arpeggiator, which can play different patterns at different speeds. Arpeggiated chordal notes play back in the order that you played them on the keyboard, so you can easily change note sequences. Each arpeggiator can be set to play at its own speed, relative to either a global or Patch‑specific Speed setting (in the range 50‑200Hz) or to an external MIDI clock rate, depending on the Sync Source setting in System mode. The Speed setting defines how often SidStation sound parameters are updated, while the Arp setting divides down from that — so a Speed value of 100Hz and an Arp value of 25 would produce four arpeggiated notes a second. When the SidStation is locked to external MIDI Clock, it updates 48 times per quarter note (or twice per MIDI Clock). This capability means that the module's arpeggiators can be sync'ed to an externally defined MIDI tempo.

Envelopes & LFOs

The SID chip also includes four ADSR envelopes (one amplitude envelope for each of the oscillators and one filter envelope affecting filter cutoff but not resonance) plus four freely assignable LFOs, all user‑programmable of course. Envelope attack durations can range from 2mS up to eight seconds, and decay and release rates from 6mS up to 24 seconds, in each case through 16 stepped values, so for instance above 750mS you can only choose from 1.5, 2.4, 3, 9, 15 and 24 seconds for a decay or release duration. There's also a Delay setting for each amplitude envelope.

In the oscillator section, oscillator pitch (for vibrato effects) and PWM width can each be modulated by any one of the four available LFOs — independently for each oscillator in Single mode. For PWM width you can set the LFO mod depth, while for vibrato you can adjust LFO mod depth and also mod wheel depth for dynamic control. You can also assign an LFO to modulate filter cutoff, and again set mod depth and mod wheel depth. And if External Clock is selected as the System Sync source, then the LFOs will be syn'ced to a MIDI sequencer or drum machine tempo.

On The Table

Another feature of the SidStation is the Waveform table, an early version of what later became Transwave synthesis on Ensoniq's synths. There are essentially two ways to use the tables: for creating new sounds by rapidly stepping through and looping around a sequence of waveforms, and for creating pitched, rhythmic note sequences. The two different applications are enabled by the SID‑table Speed setting, and can be sync'ed to MIDI Clock. As waveform tables are oscillator‑specific in Single mode, you can use them to create three‑part rhythmic sequences. In Poly mode, if Oscillator 1's Waveform table is enabled then the SidStation rotates through the tables assigned to each Oscillator in Single mode, playing a different table on each consecutive note. When you play two or three notes together as a chord, you can vary the texture by the order in which you play the notes, so you can have three‑part sequences in Poly mode as well as Single, only in this case each part is triggered at a different pitch (though at the same rate) and you can spontaneously change the pitch assignments of the sequences. To use tables in Poly mode without any problems, the individual table steps must be assigned waveforms (even if it's only the same waveform that you've assigned to the Oscillator anyway in the Wave section of Edit mode) or else turned off.

A Waveform table can have up to 32 steps, each of which can be assigned one of the five available oscillator waveforms, turned off (allowing you to create rests in rhythmic sequences), or set to Loop or End. A Loop step also lets you define the loop start step, while other step‑specific parameters available are note pitch, oscillator sync on/off and ring mod on/off. One common application for Waveform tables is creating percussion sounds, but the possibilities are quite diverse, and represent a significant and effective expansion of the SidStation's sonic palette. Meanwhile, if you're into riffs and rhythms, this aspect of the Waveform tables is a worthwhile addition and complement to the arpeggiators, while the SidStation's ability to arpeggiate Waveform table sequences provides yet another worthwhile avenue of rhythmic exploration. The Wavetables can be a bit of a pain to create, but if you persevere, the results you can achieve are worth the effort.

Filtering

As the arpeggiators and tables are both parts of the SID chip's oscillator section, the looping note sequences they generate can be routed through its filter; alternatively you can set one or more of the oscillators to bypass the filter section. The multimode resonant filter lets you select from seven filter types: low‑pass, band‑pass, low‑pass plus band‑pass, high‑pass, band reject, band‑pass plus high‑pass, and all. The resonance setting affects all of these; it's noticeable if not particularly powerful in effect, but does give a bit of added bite to percussive sounds and to note sequences, for instance. With Wrap enabled, the filter cutoff wraps from its highest to lowest value if LFO modulation pushes it above its maximum of 127 (otherwise it stays at the maximum value), providing another opportunity to create something a bit different. As mentioned previously, filter cutoff can be modified by any one of the four LFOs and a mod wheel MIDI controller. Also, the filter has its own ADSR envelope, with an Invert option that, well, inverts the shape of the envelope. Cutoff range is from 30Hz to 12kHz, and the slope is fixed at 12dB/octave.

LFOs

Each LFO lets you select from six base waveforms: triangle, sawtooth, ramp, square, random, and flat (the latter actually giving the LFO a fixed output value). You can also define LFO speed (relative to the system sync speed, which as mentioned earlier can be external MIDI Clock), invert the waveform, set AbZ on/off (on means all LFO output values below zero are inverted), set Sample and Hold on/off (this capability is applied as a modifier to the selected base waveform), and turn Lace on/off. Talk about frills! Lace actually controls the interlace speed of the LFO output and another source, which you can set to be a zero value or the output of another LFO. Yet another LFO feature is Mixer, which lets you mix two LFO waveform outputs to form a third, more complex waveform; you can also set the depth of each LFO in the mix. Each LFO also lets you assign any one of mod wheel, pitch‑bend wheel, velocity, aftertouch, MIDI controllers 20‑23, or LFOs 1‑4 to LFO speed, S/or Lace rate as mod controllers, and you can choose between LFO retriggering on note‑on or ‑off, and set a fade‑in time for the LFO.

The SidStation's sound offers oomph and bite, and provides an excellent sonic complement to clean‑sounding modern instruments. Words like rasping, crunchy, cutting, nasal, metallic, gritty and cheesy spring to mind.

Sid Star?

The SidStation doesn't sound warm exactly, nor quite what I'd call well rounded, although it is capable of producing rich, booming bass drone sounds. But if you're serious about deep, punchy, dynamic bass then the SidStation wouldn't be your first port of call, and, although it has pad sounds, 'luscious' is not a word that springs to mind to describe them; nor is 'smooth'. And if cleanliness is next to Godliness then the SidStation won't get to Heaven. Words like rasping, crunchy, cutting, nasal, metallic, gritty, and cheesy spring to mind. The SidStation's sound offers oomph and bite, and provides an excellent sonic complement to clean‑sounding modern instruments. And despite its grungy, lo‑fi nature it has a surprisingly versatile sonic character, from rich, fat and in‑yer‑face to subtle and delicate, from wild and uncontrolled to calm and gentle.

The SID chip could have passed into history as a superior computer‑games sound chip, but Elektron have succeeded in making its full synthesis capabilities accessible in a way that will be familiar to hi‑tech musicians. In doing so they've revealed its true nature as a real synthesizer, blessed with originality and inventiveness. There are a lot of things the SidStation doesn't have, and deliberately so — no instrument samples, MIDI multitimbrality, onboard effects, stereo outputs, or plentiful polyphony. But then if you want these features, go out and buy a GM/GS/XG module. If you're into creative synthesis and gritty, abstract, wild sounds, and don't mind getting your programming hands dirty, then SID could become your best friend.