# A paper cone is a piston, and the rings prove it

> A speaker cone is a shallow funnel, so the same distance along its slope covers less radius near the rim — the tightening rings are a contour map of a curved surface, not a style.

August 19, 2026 · https://justog.club/stories/speaker-cone-concentric

A loudspeaker cone, dead centre, drawn as rings running out from the dust cap to the surround. The
gap between each ring narrows the further out it goes. Four mounting holes sit in the outer rim,
and the dust cap carries a small stamped mark: 8Ω.

Nothing about this shape was drawn to look interesting. It's a picture of a curved surface, seen
flat.

## What is this, exactly?

A loudspeaker cone photographed — or, here, drawn — head-on, so that what would be a smooth slope
in profile reads as a stack of rings.

Every visible line is a contour, the same idea a map uses to show a hill without drawing it in
three dimensions. The dust cap at the centre is the small dome that keeps dust off the coil
underneath it; the surround at the outer edge is the flexible rim that lets the whole cone move.
Between them is the cone proper, and the rings are simply its slope, read from directly in front.

## Why do the rings get tighter towards the edge?

Because a cone is a shallow funnel, and the same distance along a funnel's slope covers less and
less radius the further out you measure it.

Seen from the side, a cone's profile is close to a straight line from tip to rim. Seen from the
front, that straight slope gets compressed the way a globe's lines of latitude bunch up near the
poles — real geometry, not an artistic choice. A ring an inch wide near the centre corresponds to
the same inch of slope as a ring a quarter-inch wide near the rim, because the front-on view is
squashing a three-dimensional shape into two.

## What does 8Ω mean, and is it doing any work here?

It's an impedance rating, and on the shirt it's doing exactly what it does on the cone: telling you
what electrical load this driver presents, nothing about how loud or how good it is.

Impedance is a measure of how much the coil resists the current driving it, and speakers are built
to a handful of standard values so an amplifier can be matched to them safely. It's a spec for the
person wiring the system, not a claim about performance — which is why it sits small on the dust
cap rather than anywhere it would compete with the rings for attention.

## What makes a good version of this drawing?

Letting the ring spacing actually do the geometry, rather than distributing rings evenly across
the radius for tidiness.

Even spacing looks more balanced on a page and is the wrong physics — a true contour map of a
cone has rings bunching hard near the rim and opening out near the centre, and that unevenness is
the entire visual argument for why this is a curved object rather than a flat target. Four mounting
holes, held to the outer surround where a real cone actually carries them, keep the object
legible as hardware rather than as an abstract pattern.

## Can a real manufacturer's cone or badge go on the shirt?

The cone shape and the rings it makes are physics, and nobody owns a curve.

What a manufacturer does own is their dust cap badge, their model name and any distinctive cone
material or colour treatment built to be recognised at a glance — that's a designed identity,
licensable the ordinary way if a real one is the point. An unbadged cone with a generic impedance
figure stays a drawing of how a driver is built, not of whose driver it is.

## Does this work for anyone who isn't into home audio?

Anyone who has ever taken a speaker apart, or wired one into a car door, a garage, a boat — the
cone looks the same whether it's driving a hi-fi or a PA stack.

It also works simply as a shape: a set of tightening rings around a centre reads as a target, a
sound wave, a piece of hardware, depending on who's looking, and it doesn't need the wearer to
know what a dust cap is called to land.

## Does it print well?

Very — this is a halftone drawing already built from rings, so the print technique and the subject
are the same thing.

Cream rings on a dark ground keep every ring distinct without needing more than one colour to do
it. Hold the ring count to what the drawing shows clearly at chest size rather than the number a
real cone might actually carry — [fewer, coarser rings survive the weave better than a fine set
that blurs together](/stories/microphone-grille-mesh), and the 8Ω mark wants setting large
enough to stay legible rather than shrunk to real-world scale.

## How do I get one made?

Describe the driver at [JustOG](/) — the ring count, the impedance figure, and how many mounting
holes to show.

Pick a direction, drag the crop frame, see it composited on the real garment, and it's made to
order and shipped.

Designs other people have published are in the [shop](/shop).

A dust cap at the centre, a surround at the rim, and every ring between them a measurement of the
same slope.