Cong Burn Stacks

Stacks is a busy environment visually, but easy enough to understand, with no cryptic labelling. This is the VST3 version, with its resizable window, and with three looper tracks loaded.

If you want proof that original independent music software is still flourishing, you need look no further than Stacks.

Stacks is a new virtual instrument for macOS, Windows and iPadOS by Cong Burn, the software development arm of British electronic artist and programmer John Howes. It follows on from Strokes, which I reviewed in the June 2024 issue of SOS, and shares a similar left‑field, minimalist, modular‑inspired character, and is similarly affordable.

If forced to summarise what Stacks actually is, you’d have to say it’s a four‑track looper with an onboard synth, audio input, step sequencers, modulation sources and effects. Particularly in its standalone app form, on the iPad, it has sufficient scope to create exploratory long‑form pieces all by itself, and perhaps even a longer ‘set’: sequencers and modulators drive the synth, the output of which (or another incoming live signal) can be captured and layered in the loopers.

The same and more is possible with Stacks running in a DAW or other host, in plug‑in form (AUv3 for iPadOS, AU for Logic, and VST3 for everyone else on macOS or Windows). However, Stacks is open‑ended, and I think it’s likely some users will have it for its multitrack looping alone. It’s also not strongly deterministic, in the way a linear timeline‑based DAW is, but more of a platform for experimentation and for generating that old friend, the happy accident.

Stacked

A visual scan of Stacks’ main interface is potentially a bit overwhelming at first — it’s a very ‘busy’ design — but the main sections are easy enough to spot. Two step sequencers (one primarily for notes, the other for modulation) towards top left. Synth and effects top right. Various modulation sources plus mode/view buttons (and, on the standalone app, transport controls) at bottom left. And then at bottom right the four parallel loopers. However, this is only the ‘Main’ layout, and others reconfigure the interface, opening up new panels or increasing the size of existing sections. For example, the Loopers mode increases the size of all four looper tracks and hides the sequencers and the synth almost entirely. The way elements interrelate remains very clear at all times though.

While the default Main window layout gives an overview of all four looper tracks, an alternative view opens up all the parameters for pairs of tracks.

Such is the depth of functionality in Stacks I dare not try to describe all its features. But I’ll focus in on a few to hopefully give a flavour of the what, how and why.

Let’s take the uppermost step sequencer, Seq A, for starters. Its main role is to send notes to the onboard synth (and, for good measure, across virtual MIDI too). You specify note pitch by dragging faders, with the option to generate single notes or many types of chords.

An eight‑step design might look rather limiting, but these are actually eight ‘stages’, individually adjustable in length and with varying numbers of notes triggering (like a ratchet) within that length. Ensuing rhythmic subdivisions can range from downright predictable to exotically discombobulating. There’s even a way for the note triggers within a stage to be skewed, for a ‘bouncing ball’ effect. Equally, you can dial in rests, or skip stages completely. An overall Steps parameter sets the ultimate musical length of the loops you create here. It doesn’t alter the number of stages but...