Source Focusing

THE PROBLEM

A focused source is easy to claim, hard to keep

Placing a virtual source between the array and the audience — a voice suspended over the crowd, an effect that arrives from mid-room — is one of the most striking things a spatial system can do. But a focused source is a delicate interference pattern: easy to produce at one point, hard to keep across a room, and quick to collapse into pre-echo and comb filtering when it meets real, non-ideal speakers.

DAM Audio ships two focusing engines for it. They answer the same question — how do you bring a source in front of the array, cleanly? — at different budgets, trading cost and complexity for how much of the audience the illusion has to reach.

FIRST APPROACH

FSS — from timing alone

Focused Source Synthesis is the light approach: it reverses the order in which the loudspeakers fire, so the wavefront converges onto the source position before spreading to the audience — a focused source at the cost of a delay line. An aperture taper trades a little sharpness for cleanliness, and it engages only when the source is genuinely in front of the array, so it can never make things worse.

Delay-and-gain only, FSS costs almost nothing and runs where a full solver cannot — an embedded processor, a lightweight touring rig, the array objects in our Max/MSP externals. Its focus is honest and clean for one listening zone.

SECOND APPROACH

PMS — over a whole area

Pressure-Matched Synthesis is the more advanced engine. It states focusing as a reproduction problem: it solves the loudspeaker signals that recreate the source's sound field across a chosen region of the room, not just one seat. A regularised inverse keeps the result stable across the band, each loudspeaker's real directivity and output feed the solve, and the heavy computation runs off the audio thread — swapped in without a click.

The result is a focused source that holds for a section of the audience rather than a single chair, delivered at zero added latency through the same zero-latency convolution engine as our transaural filters. A safety envelope reports where the geometry can actually hold a clean focus.

WHICH ONE

When to choose which

They form a ladder, not a pair: FSS is the light, portable entry point; PMS is the more advanced, reference-grade engine that holds a full house. Most systems start with FSS for the gesture and step up to PMS when the source has to survive a real audience.

APPLICATIONS

Where it fits