GLX Audio Co Ltd - Balsam

Balsam is an eight-voice hybrid polysynth from GLX Audio, and the first thing you notice is that there's no keyboard. In its place sits a row of eight sliders, laid out like a small mixer, each one an independent pitch-bender for a single voice. GLX call it a modal synthesizer, and their idea came from two very different places: the pedal steel guitar, with its pedals and levers sliding into pitch, and the long polyphonic portamento of instruments like the Oberheim OB-8 and Yamaha CS-80 — those sweeping chord changes that take several seconds to arrive and merge.

Balsam is an instrument built around gradual movement — for a general idea, put on Alice Coltrane's Turiya Sings or the ashram tapes that followed (much of that later material drenched in an OB-8, a synth her daughter Michelle suggested she pick up). Yes, an absolute magic album btw..!

Anyhow — because there's no piano-style keyboard, the tuning works its own way. A tuning here is eight notes, played on eight keys, plus eight pitch bends laid across the sliders. An encoder wheel switches between tuning banks, and you can transpose the whole set on the fly or jump octaves as you play, alongside a pitch wheel and a key latch. It's an unusual layout, but it steers you towards playing in gestures — sliding, holding, nudging voices apart, rather than hammering out notes.

Glide is definitely a strong part of Balsam's character. Three polyphonic modes are on offer: fixed rate, the classic OB-8-style portamento; fixed time, where every note in a chord lands together for a more modern feel; and fixed interval, where each voice sets off from a musical interval and glides home. On top of that sits Viscosity, a feature unique to Balsam that adds drag to your slider moves, so the oscillators lag behind your hand and ease towards their target. Since oscillator 1 and oscillator 2 can each run their glide and viscosity at their own speed, a single voice can thicken, phase and beat against itself — from a gentle chorus-like shimmer to pronounced, out-of-tune-y things. Flip the pitch-invert toggle and the whole chord bends at once. Absolutely lovely, sweeping stuff…!

Under all this is a solid synth engine. Each voice has two oscillators with waveform, tune and glide controls, plus sync, a sub-oscillator and noise, running into an analogue state-variable filter and analogue VCA in stereo. Three envelopes, an LFO and a hidden mod matrix handle modulation, much of it slider- and key-tracked. In place of the usual arpeggiator or step sequencer, Balsam has an eight-channel polyrhythm sequencer: it gates voices on and off at clock subdivisions you set — and reshape — with the sliders, which is very nice for crossrhythms and hemiolas when quantised, or, unquantised and slowed right down, for evolving drones and tanpura-like textures. A digital shruti box, more or less. MPE output, a browser-based editor and the usual MIDI, clock and pedal connections round it off.

Balsam is a specialist rather than a do-everything polysynth, and that's sort of the point — it's for slow harmony, drifting chords and music that changes shape while you hold it. An absolute beaut' of a thing to look at and to play… let's leave it at that :)

Features:

• Eight-voice hybrid modal polyphony (digital virtual-analog oscillators, analogue filter and VCA)
• Two oscillators per voice with waveform, tune and independent glide/viscosity, plus sync, sub-oscillator and noise
• Eight sliders as independent per-voice pitch-benders
• Eight trigger keys for single notes or chords
• Three polyphonic glide modes: fixed rate (portamento), fixed time and fixed interval
• Viscosity — slew/drag on pitch-bend movement, with per-oscillator speed
• Pitch-invert toggle for bending whole chords at once
• Eight-channel polyrhythm sequencer, quantised or unquantised
• Stereo analogue state-variable tone filter (4-pole / 2-pole)
• Stereo analogue VCA
• Three ADSR envelopes (amp, filter, mod) and an LFO
• Mod matrix with slider-tracked and key-tracked modulation
• Slider-tracked stereo panning
• Just and equal intonation modes with multiple tuning banks
• Octave transpose, pitch wheel and key latch
• MPE (MIDI Polyphonic Expression) output
• USB-C MIDI in/out
• 5-pin MIDI in/out
• 3.5 mm analogue clock sync in/out
• Expression pedal input
• External audio input
• L/R line outs plus headphone out
• Browser-based tuning, settings and firmware updater