Luma

Overview

Luma is a mobile synth that distils the joy of dedicated, tactile hardware instruments into something that lives in your pocket. I lead the design and build it in Swift. The bet driving every decision: reward playfulness over menus. Pick it up, hold a chord, lock a pattern, and you are making music inside a few seconds, not a few screens.

The problem with synths on a phone

The best dedicated hardware synths work because they limit you on purpose. A fixed set of controls, no menus, and your hands never leave the instrument. Most mobile synths throw that away, burying play behind tabs, modals and preset libraries. The design problem was to keep a phone's flexibility while protecting the one thing that makes those instruments fun: you never stop playing to change something.

Exploring the playing surface

I started wide, sketching the whole instrument as a single surface rather than a set of screens. These early wireframes tested how much could share one canvas before it got busy, and where a control could move without pulling your attention off the performance.

Designing the joypad

The joypad is the one control you never want to leave, so it took the most iteration. It had to map both chord and pitch to a single thumb-friendly surface without feeling like a compromise. I explored a crosshair pad, twin ribbons, a hex pad and a ring-arc knob, testing each for reach, accuracy and how it felt under sustained use.

Resolving the main screen

Around the joypad, the main screen had to hold tempo, pattern and key without crowding the thing you actually touch. I tested a radial chord wheel, an in-place recorder with a takes list, and an X/Y timbre pad, keeping whatever stayed legible at a glance mid-performance and cutting the rest.

Shaping the sound without stopping

Effects and oscillator detail are where most synths force you into a menu. Here they lift up as a sheet over the playing surface instead of replacing it. Tweak a setting, drop the sheet, keep playing, the take never breaks. That single interaction rule did more for the feel of the instrument than any individual control.

The only screens that step off the surface

Settings and a Recordings library are the only places you leave the performance, by design. They stay deliberately plain so there is nothing to learn and nothing to get lost in before you are back on the instrument.

User testing

I tested some of the wireframes with people who actually play, both musicians used to hardware synths and people who had never touched one. The questions that mattered were not about whether the UI was tidy, but whether the core bet held: could someone pick it up and make a sound they liked before they thought about the interface?

A few things only showed up once people had it in their hands. The joypad mapping that read clearly on screen needed a larger target and clearer feedback under a moving thumb. The lift-up sheets for effects were understood instantly, that interaction needed no explanation. And the bits people reached for first told me what deserved to stay on the main surface and what could move off it. Those sessions shaped the joypad sizing and the decision to keep editing as an overlay rather than a screen of its own.

Prototype

Before committing to the resolved design, I built a working prototype with live audio running in a PWA, the fastest way to feel whether the interaction actually held up under playing. These are early, rough by intent, and not the finished synth. Press play to see the playing surface, joypad and recorder in use.

Where it landed

The resolved design pulls every decision back onto one surface: a clear chord display, the central joypad, and the diatonic chord row within thumb reach. Everything earned its place by surviving the same test, does it keep you playing?

Controller support

Pairing a DualSense moves the playing surface off-glass. The sticks and triggers map to the joypad and the BPM controls, so the touchscreen becomes a dashboard rather than the instrument itself, useful when you would rather hold something with both hands.

Design principles

The hardware instruments that inspired Luma nail the same idea: limit the player's choices and you free them to actually play. Luma takes that philosophy onto a touchscreen, then offers the DualSense as a way to put a physical surface back in your hands when you want one.

Every screen is built around playing first and editing second. No preset library, no nested menus, no modal dialogs. The whole interface is one performance surface.

Status

Luma is in active development. Next explorations include effect chains, song sections, and extending controller support to other gamepads.