A couple of years ago it seemed like dual-peak filters were the hottest thing happening in modular and everyone had to have one in their rack. Some of the modules that were coming out at the time seemed pretty similar in terms of function, size, and even layout, with all of them seemingly adoring symmetry—understandably—and adhering to the design elements of such. Here we are a couple of years later, and while the buzz about dual filter modules has lessened, it’s given a little breathing room to offer “other” approaches for dual-peak filtering. Ikarie is one such module, a filter made in collaboration between Václav Peloušek of Bastl Instruments and Peter Edwards of Casper Electronics, and aptly named after the 60s Czech sci-fi space odyssey movie, Ikiari XB-1.
Where its predecessors offered control of seemingly every parameter, Ikarie’s designers have come up with a unique module that yields many excellent opportunities for stretching [or filtering, rather] the sound barrier, all without being the size of a small desktop synth. While symmetry is typical for anything dual, twin, or otherwise, there is nothing symmetrical about Ikarie—it’s as unique as it is powerful.
Ikarie can be either a stereo or dual peak filter and can morph continuously between lowpass and high-pass filtering. The two filters are 12dB each and normalled in parallel, but can be chained together [patch the L OUT into the R IN] for use as a 24 dB filter. The L input is normalled to the R input for stereo filtering, and along with the L and R outputs, there is a BEYOND output, which produces the difference of the two filters—making it possible to get some ring modulation—and transforming Ikarie into a twin-peak/bandpass filter. Ikarie also gives you the ability to use the outputs in tandem for stereo applications, or split apart so that you can send each output to wherever your heart desires to get as spacey as your rig will allow. That’s a lot of functionality—a lot of variables—for just the ins and outs.
Ikarie sports the requisite large [relatively speaking] center-stage filter knob, which resides at the top of the module and is illuminated by a glow through area in the PCB solder mask, and also surrounded by constellation-like tiny holes in said PCB for a light up galactic effect. As for other controls, a diagonal resonance slider [Bastl just loves diagonal, don’t they?!] adds a bit of design idiosyncrasy to Ikarie, and you’ll also find three other knobs: STEREO, INPUT level, and MODulation amount. There are also dual built-in VCAs for each filter, an envelope follower for the input —with a three-position decay switch—and the ability for driving the input signal to get a little dirt by adding up to five times the gain. There’s also a 1v/oct input, and as Ikarie self-oscillates easily, it works pretty well as a tunable sound source.
One of the ways that Ikarie maintains its smaller footprint in comparison to its contemporaries is by utilizing one controller [knob, switch, etc.], where others have two. Having all of the knobs be center position off gives each a left and a right side and the ability to control so much, with so little.
The best example of this is the CUTOFF knob, which [when devoid of CV/modulation/etc.] is open in the middle position and sweeps the lowpass filter when turned left, and the high-pass when turned to the right. This effect can be modulated by adding a little something from the MOD knob—found towards the bottom of Ikarie—or CV controlled. The MOD knob is cool because it’s an attenuverter, not just an attenuator, and can invert the incoming CV. Ikarie has a trick up its sleeve by having an internal envelope follower normalled into the MOD, so there is always modulation available [turned off by setting MOD in its center-off position]. There is a lot of normalization in Ikarie, and no stone is left unturned, no potential connection left un-normalled here, and it’s much appreciated. As well, patching external CV for modulation of the filter turns the MOD control into an attenuator for the incoming signal.
Since we’ve brought up the envelope follower, let’s talk about that for a minute. It takes its signal from the L input and is normalled to the cutoff frequency via the FOLLOW switch and MOD knob, but can be patched out via the FOLLOW jack. As stated before, this allows for modulation of the filter without needing any other module to do so, and self patching the follower into the STEREO or RESONANCE brings about some cool effects and with the normalling can create auto-wah type stuff and really interesting rhythmic and melodic results. The three decay switch is a nice touch as well as it gives quick and easy control over shaping the envelope a bit.
Moving to the STEREO section of the filter, there are two toggle-switchable states for this section—PAN and SPREAD—and by using the single STEREO knob to control both filters—while in SPREAD mode—you can simultaneously increase the cutoff of one filter, while decreasing it in the other, similar to a tilt function found in some EQs. The results can get dramatic quite quickly the more the knob is turned either way, and patching some CV into this [turning the STEREO knob into an attenuator for the incoming CV signal] can create some great stereo effects. Switching to PAN mode and the STEREO knob decreases the output of the opposite filter for whichever way the knob is turned. Adding some CV to this makes for some interesting stereo panning of the filter. It’s hard to overstate how much can be done with such a simple seeming idea, and the STEREO section—just a knob, a jack, and a switch—is a really versatile setup and executed really well.
The controls on Ikarie are all pretty intertwined, for example the position of the STEREO knob affects the CUTOFF which affects the BEYOND, and CV-ing anything can change everything quickly.
I’m really impressed with Ikarie. I can’t recommend it enough if you’re looking for a dual filter, especially if you need it to fit in a smaller space. Spooky tremolos, percussive yips, vintage sci-fi raygun, trapped aliens screaming for help...they’re all in here, and much much more. Ikarie is a really well designed module, and while other twin filters might give you more controls at your fingertips, I’m not sure there are any the have such a unique combination of controls, and that are so quick, easy, and fun as Ikarie, and packaged in such a manageable size. Killer module.
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