Loudspeaker Enclosure Design — Andrew Payor (Rockport) interviewed by Jonathan Valin

A blog-format Q&A in The Absolute Sound (2026-09-12) in which Jonathan Valin asks one question and Andrew Payor, founder of Rockport Technologies, answers at length. The subject is not alignment — sealed, vented, Qtc, none of that appears — but the two things the spoke's loudspeaker-enclosure page had covered in a paragraph: the cabinet's own resonance and its shape. Everything here is a manufacturer describing his own products in an enthusiast magazine; the one measurement quoted is someone else's.

Stiffness, damping, mass — and why one material cannot give all three

Payor's argument starts in turntable plinths (late 1980s) and moves to boxes by analogy: both need high stiffness, high mass and high damping, and "stiffness and damping are mutually exclusive attributes in a single material". His answer, borrowed from naval architecture, is the sandwich composite: two high-tensile skins over a heavy, high-hysteresis core. The number he leans on is that a sandwich panel's stiffness goes with the cube of its section thickness — the same skins over a 2-inch core are 8× stiffer than over a 1-inch core. A moulded shell also has no joinery or fasteners, and can be any shape.

The lineage he gives: Procyon (1993), glass-fibre dual shell with a damped-polymer core and a constrained-layer aluminium sub-baffle; Antares, of which John Atkinson (measuring for Michael Fremer's Stereophile review) wrote that its construction "reduces panel resonances to below the resolving power of my measurement" — Payor adds that nothing has measured better in the 24 years since, which is his claim, not Atkinson's; Arrakis (2005) and Altair (2006), the first with 3D modelling and tooling; Lyra (2016), a dual-shell cast-aluminium outer with damped-polymer core, trade-named DAMSTIF; Orion (~2026), DAMSTIF2, carbon-fibre outer shell over the cast inner housing, lighter and cheaper; Lynx, DAMSTIF3, integrally cast ribs and a thick extensional viscoelastic layer "approximately the same hardness as a hockey puck".

Why it matters, in his framing: a 1-inch dome tweeter radiates from ~0.8 in², a floorstander's cabinet from thousands, and coupling efficiency scales with area — so a small panel motion is a large acoustic contribution, arriving late (energy storage and release) and from a place that is not the driver. Every effort at a point source — driver spacing by wavelength at crossover, baffle design, the crossover itself — "become moot" if the box radiates on its own.

Shape: the baffle step and the snapped-off wave

"Hands-down, the chief arbiter of a clean wave launch from a loudspeaker is enclosure shape." Payor credits Harry Olson's 1950s work on how cabinet shape affects the baffle step (the transition from 2π to 4π radiation as wavelength grows past the baffle) and edge-diffraction: the wave travelling across the baffle meets the sharp edge and "snaps off", becoming a second, delayed source that comb-filters against the first. A chamfer or radius helps only when it is broad — "more like large facets" — and any discontinuity (gaps, steps, edges) does the same damage. His cabinets use large sweeping chamfers and continuously changing baffle dimensions for that reason.

What to keep, and how much to trust it

• The four tenets — high stiffness, high damping, high mass, and geometry for a clean wave launch — are a usable checklist and consistent with the spoke's existing framing.
• The cube law for sandwich stiffness is standard beam theory, stated without derivation.
• The only measurement is one sentence of Atkinson's, quoted second-hand and undated; no accelerometer plots, no resonance frequencies, no before/after on any DAMSTIF generation. "Blacker background", "explosive dynamic contrasts" are listening claims by the maker.
• The cost argument — the enclosure is "the lion's share of expenditure" in high-end speakers, so it should be where the money audibly goes — is also the sales pitch.

T3: a first-party account of proprietary products, via a magazine that reviews them, with one borrowed measurement. Ingested because it is the corpus's first source on cabinet construction and diffraction as design problems in their own right, not for its numbers.

Cross-spoke context

The magazine is paged in ../music-tech-wiki as music-tech-wiki/the-absolute-sound; linked, not re-paged. Rockport Technologies and Andrew Payor are named once here and deferred.

Related

loudspeaker-enclosure · edge-diffraction · chesky-audio-lc2 · loudspeaker-driver · crossover · synthesis