What Are Omni and Theremin, the Web Instruments on Femur?

Omni and Theremin are two browser-based instruments by Luke Phillips, the design engineer behind femurdesign.com. Omni is a tactile web instrument for playing and learning musical scales from different cultures, built around a pitch constellation, harp, effects, harmonies, and loop recording. Theremin is a multi-touch Web Audio synthesiser, created in 2014, for shaping waveforms, delay, feedback, and scuzz directly in the browser. Both run in the browser and reflect Phillips's stated goal of making complicated musical ideas feel immediate and playable.

Omni: Playing and Learning Scales From Around the World

Omni is described on Femur as "a tactile way to play and learn musical scales from cultures around the world." Its listed components are:

• Pitch constellation — a spatial layout of pitches, rather than a linear keyboard or a list of note names.
• Harp — the primary playing surface.
• Effects — processing applied to the sound.
• Harmonies — additional pitched material layered with what you play.
• Loop recording — capturing a phrase and playing it back.

The design intent is consistent with the rest of Phillips's work: replacing knobs, sliders, menus, numbers, and text with space, colour, movement, and shape. For a learner, the pitch constellation is the part worth paying attention to — it presents scale relationships as positions in space, which is a different mental model from reading note names off a staff or a piano roll.

How to approach it

1. Open Omni in a browser from the Femur site.
2. Start with the harp and a single scale, so the pitch constellation has a clear reference.
3. Add harmonies once the scale layout is familiar.
4. Use loop recording to capture a short phrase and hear it against the effects.

The expected result is that you can play a scale you don't already know by position rather than by name. The common sticking point is treating the constellation as decoration — it is the navigation layer, so it pays to read it before playing.

Theremin: A Multi-Touch Web Audio Synthesiser

Theremin dates to 2014 and is described as "a multi-touch Web Audio synthesiser for shaping waveforms, delay, feedback and scuzz directly in the browser." Its parameters are:

Unlike a physical theremin, which is played by moving hands near antennas without touching anything, this is a multi-touch instrument — you shape the sound through touch on a screen. The name is a reference to the hands-in-air playing style and the continuous, expressive control it implies, not a claim to replicate the hardware.

What to expect when playing

Multi-touch means more than one finger can affect the sound at once, so the instrument rewards gestures rather than single taps. Feedback and scuzz are the parameters most likely to produce extreme or unpleasant results at high settings, so it is worth moving them gradually and keeping output volume moderate while you learn the range. The synthesiser runs on Web Audio, so it needs a browser with Web Audio support and, in most browsers, a tap or click before audio starts — a standard autoplay restriction rather than a fault in the instrument.

How the Two Differ

Both are free-to-open browser instruments by the same author, but they serve different purposes:

• Omni is pitched at learning and playing scales, with structure provided by the pitch constellation and harmonies.
• Theremin is pitched at sound design and expressive touch control, with structure provided by waveform, delay, feedback, and scuzz.

If you want to understand how a scale from another culture is laid out and then play it, Omni is the relevant tool. If you want to shape a raw synth sound with your fingers and push it toward noise, Theremin is the relevant tool. Neither requires installation; both are reached from the Femur site.

Who Made Them and Why It Matters

Luke Phillips describes himself as a software engineer and musician working across music technology, creative tools, and AI, with more than a decade building interactive instruments and learning products — from browser-based synths to cross-platform apps and spatial hand tracking. His stated aim is to build things that make complicated musical ideas feel immediate and playable, with the technology getting out of the way as quickly as possible.

That context explains the design choices in both instruments. Omni's constellation and Theremin's touch-and-gesture control are both attempts to remove the interface layer between a musical intention and the sound, which is the same thread running through his other projects, including Funputs, BlokDust, and his work at ROLI on piano learning and gesture-based sound control.