Developer SLM Audio has released Gleo, a free dystopian-themed virtual instrument for macOS and Windows.
I mention it here because SLM Audio and Gleo remind me of Gait Runner in the sense that they are built around a very distinct backstory, albeit we are staying on planet Earth this time.
SLM Audio describes itself as a “semi-fictional” audio plugin company.
I’m sure we all have a semi-fictional friend; we know they’re real, but everything else is firmly rooted in make-believe.
Anyway, in this case, Gleo is based on a fictional object recovered from the Atlantic Ocean off the coast of Crookhaven, Cork (Ireland), by a diving crew in 1904.
This fictional object/instrument of iron and marble brought with it the sounds and secrets of those deep waters.
While the ocean or sea can be extremely peaceful, the element of the unknown and tales of tragedy and otherworldly happenings can have a distinctly ominous aura, and that’s the sound captured by Gleo.
While a resonator-based plugin like AAS Objeq Delay typically deals with the physical modelling of real-world objects, what we have here is fictional modelling, I guess.
Gleo brings this mysterious fictional instrument to life, and it’s great for tense drones or atmospheric beds.
You can think melodically with Gleo, but it’s more about emotion and texture. When you think about the natural noises from the sea, then things like foghorns, the uneasy feeling they create is more impactful than the sound itself.
One of the cool things that Gleo does to highlight emotion over sound is to allow MIDI velocity to control articulation rather than just volume. Softer notes act more like harmonics than full-bodied notes, creating the sense of a real tactile instrument.
Gleo isn’t an overly versatile instrument, and you won’t do a million things with it, but what it does, it does well.
Besides the scratchy, tension-filled drones, you can create some gorgeous pulsing pads, and everything has that haunting quality. You can also craft awkwardly grating metallic pedal notes that work so well in making an audience feel uncomfortable.
Gleo is also the perfect name; in Irish, gleo can refer to the ominous roar of the sea that fuels many age-old superstitions.
Gleo is available in AU, VST3, and CLAP formats for macOS (10.15 or later) and Windows (10 or later).
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Last Updated on May 21, 2026 by Tomislav Zlatic.
