Madrona Labs Aalto

If your music depends on pleasant, mellow sounds, skip this article.
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By Jim Aikin

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If your music depends on pleasant, mellow sounds, skip this article. You don’t want to know about Aalto! This affordable but powerful plugin is all about rude, aggressive, metallic tones. Some of the factory presets are just plain out of control. As a diehard modular junkie, I’m happiest when I have a rack full of oscillators and processors at my command, so I was put off at first by Aalto’s modest lineup of modules. Before I knew what hit me, I was designing new presets and saving them.


Aalto’s design packs more than a few surprises. In part it seems to have been inspired by Don Buchla’s modular synths. Across the top are five modules that serve as sources for control signals—Key, Sequencer, LFO, and Envelopes 1 and 2. Across the bottom are five audio modules— Complex Oscillator, Gate, Waveguide/Delay, Filter, and Output. The dark band along the middle is the patching matrix. You can mousedrag cables from any outlet in the upper row to any of the little dials, which are inlets and depth controls for the control signals.

There are inlets in both the control modules and the audio modules, and multiple cables can be attached to both inlets and outlets, so the patching possibilities are vast. However, there’s no way to modulate the depth amounts themselves using yet another signal. You can, however, automate them in your host.

Double-clicking these small knobs zeros them, which is a great help. Even better: Image-Line FL Studio displays Aalto’s changing knob values in real time in its own parameter readout. Sweet! On the flipside, Aalto is not compatible with FL Studio’s implementation of MIDI controller data. It responds to note messages just fine, but pitch-bend doesn’t work, and response to the modulation wheel and aftertouch is very slow. The same controller inputs worked smoothly when Aalto was running in Ableton Live, however.

Aalto is something of a CPU hog, and has only four-note polyphony. If you need big chords, you can run two instances, but you may end up freezing tracks to free up your CPU. Aalto’s larger knobs are also animated meters, which helps you see what the signal is doing at that point in the patch—think of a tiny oscilloscope warped to fit the knob.


Time for an old-school Keyboard tweakhead review. Starting at the upper left , the Key module has outlets for pitch, velocity, voice number, aftertouch, and one MIDI control change message of your choice. Thanks to the voice number outlet, the four voices in a drone patch don’t have to sound alike.

The Sequencer has 16 sliders. Below each slider is a gate on/off button for setting up rhythms in the envelope generators. Both the slider row and the gates have immediate and delayed outputs, and the delays can be set from half a step to eight steps, so complex “chase-me” sequences are easy to set up. Envelope 1 responds to the non-delayed gate and Envelope 2 to the delayed gate. The gate output can also run the Gate module directly, freeing up the envelopes. Sequences can have fewer than 16 steps if desired.

The Sequencer can run in looping or one-shot mode. The sliders’ output can be quantized to play in equal-tempered half-steps, and the gate width can be adjusted. Less obvious, but just as important, the sequencer is polyphonic: Each of the four voices has its own sequence. While the sequence is the same for each voice in a given patch, the sequences don’t have to run in unison.

The LFO outputs a sine wave, which can be crossfaded with a noise source. There’s a patching input for controlling the frequency. When the noise source is used by itself, the frequency control lowpass-filters the noise—handy for gargling effects. There’s no patching input for amplitude, so controlling vibrato depth from the mod wheel is tricky, but I found two ways to do it by patching, at the cost of making other features unavailable.

The first envelope is a standard ADSR with optional velocity control of the output level. The second envelope is simpler—or is it? It’s a delay/attack/release type with a switchable hold. It can also be set to repeat, turning it into a separate LFO. The only modulation input is for the repeat rate.

Turning to the bottom row, the Complex Oscillator has tone controls for waveshape (adjustable from square through sine to saw), timbre (which adds overtones in an intelligent way, without aliasing), and modulation index (for controlling the FM carrier from the modulator). The timbre knob affects sine waves most strongly, but has less effect as the waveshape knob tilts toward saw or square. The modulator has its own output, so it can also generate a sub-octave or separate overtone.

The Gate is almost like a VCA, but not quite. It’s positioned before the Waveguide and Filter, so the Waveguide can ring out, producing a tone long after the gated note you played from the keyboard has stopped. This is not a problem—it’s an effect, and a cool one. The gate can be left open in the absence of an envelope input for drone patches.

If the “lopass” button is clicked, the Gate also functions as a simple but fat lowpass filter. The smoothing function on the release turned out to be an emulation of the Vactrol opto-electric gain control found in Buchla synth modules. This is useful when the Gate is run from the Sequencer, as it can produce a short release segment even when no envelope generator is patched to the input. The Vactrol emulation also has a unique character that’s ideal for glitchy, percussive sounds.

The Waveguide/Delay is the least conventional module. The frequency of the delay loop can be set from 0.86Hz clear up to 3,520Hz, and can be modulated. Feedback and overdrive are included, so you can do anything from standard echoes and vibrato to pitched resonator effects. Runaway feedback is not just a danger here—it’s a temptation. A single band of EQ is in the delay feedback loop, for pulling out resonances. And every one of these features can be controlled via patch cords. There’s no sync of the delay time to the host, nor to the internal step sequencer, but you can adjust it manually and get what’s effectively a synced sound.

The filter input is a mix of the oscillator/gate signal and the waveguide signal. There’s no patching control of this mix, but you can automate it in your host. The state-variable filter is continuously adjustable from lowpass to highpass to bandpass, and the response can be patch-controlled, as can the cutoff and resonance. The filter cutoff has only one modulation input, which limits your ability to apply an envelope while tracking the keyboard. You can patch both the keyboard pitch and the envelope to the cutoff input, but they’ll always have the same depth, because there’s only one input amount knob.

Last is the Output module, which features a decent-sounding reverb with a wet/dry knob. The panner in this module is a handy place to patch the voice number output of the Key module. Switch on unison mode, and the four voices will be panned to different locations.


Aalto is deceptively simple and seriously addictive. If you’re scoring sci-fi soundtracks, it may be your next go-to soft synth. For rich string pads and realistic electric pianos, look elsewhere. Once I understood its more arcane features, patching turned out to be great fun. The sounds I programmed were exotic and rather startling. Aalto is not going to set the synth world on fire, but it might give your listeners a serious anxiety attack—in a good way.


PROS Exotic sounds and unusual synthesis features. Highly patchable. Nearly all parameters can be automated in your host.

CONS Single-oscillator voice. Limited polyphony. No MIDI learn.

CONCEPT Patchable virtual modular synth with no hidden features— what you see is what you get.
SYNTHESIS TYPE FM plus subtractive. Carrier oscillator has variable waveshape for saw and square tones.
COMPATIBILITY Mac OS and Windows. AU and VST, 32- and 64-bit.