What is a Loudspeaker made of?
What is a Loudspeaker made of?
A paper or plastic cone hung on a rubber surround, driven by a coil in a magnet gap.
The classic failure of a speaker that has sat unused for two decades is the surround: polyurethane foam surrounds hydrolyse and crumble, so the cone flaps loose and the bass disappears, and re-foaming kits exist precisely because the rest of the driver is usually fine. Rubber and cloth surrounds do not do this and can last indefinitely. The other thing worth knowing is that speakers are inefficient in a way nothing else in the house is — a typical domestic driver converts well under one per cent of the electrical power into sound, and everything else becomes heat in the voice coil.
Component by component
| Part | Material | Why that material |
|---|---|---|
| cone | pressed paper pulp, polypropylene, woven glass fibre or aluminium | The cone must be light, stiff and well damped — paper is remarkably good at all three, which is why it survives after a century. |
| surround | butyl rubber, treated cloth, or polyurethane foam | It seals the cone to the frame and lets it move axially; foam surrounds are the ones that crumble to dust after ten to twenty years. |
| spider | resin-impregnated corrugated cotton | It centres the voice coil in the magnet gap while allowing travel, so the coil never rubs against the pole piece. |
| voice coil | copper or aluminium wire on a Kapton or aluminium former | It has to shed heat — the vast majority of the amplifier power becomes heat in the coil, and burning it out is how speakers die. |
| magnet and basket | ferrite or neodymium magnet on a stamped steel or cast aluminium frame | A cast frame resists the flexing that a powerful magnet and heavy cone impose, which stamped steel does not. |
| enclosure | MDF or plywood, sealed or ported | The box exists to stop the rear wave cancelling the front one; MDF is used because it is dense, uniform and does not ring. |
Other electronics objects
- Alkaline battery Zinc powder and manganese dioxide either side of a potassium hydroxide paste, in a steel can.
- Smartphone screen Chemically strengthened aluminosilicate glass over a touch layer and an OLED or LCD panel, with an oil-shedding coating on top.
- Solar panel Doped silicon wafers with silver contacts, sealed between low-iron glass and a plastic backsheet in an aluminium frame.
- LED bulb Blue LED chips under a yellow phosphor, plus a driver circuit and a heat sink — and it is the driver that dies.
- Touchscreen A grid of transparent electrodes measuring the tiny capacitance your finger adds — which is why gloves fail.
- Computer keyboard ABS or PBT keycaps over either a silicone rubber dome on printed film, or individual mechanical switches.
- Headphones A neodymium magnet, a coil of copper wire and a thin plastic diaphragm — a loudspeaker shrunk to fit an ear.
- Computer mouse An ABS shell around a tiny camera taking thousands of pictures a second, plus two clicky microswitches and PTFE feet.
Common questions
- What is a Loudspeaker made of?
- A paper or plastic cone hung on a rubber surround, driven by a coil in a magnet gap.
- What is the cone of a Loudspeaker made of?
- Pressed paper pulp, polypropylene, woven glass fibre or aluminium. The cone must be light, stiff and well damped — paper is remarkably good at all three, which is why it survives after a century.
- What is the surround of a Loudspeaker made of?
- Butyl rubber, treated cloth, or polyurethane foam. It seals the cone to the frame and lets it move axially; foam surrounds are the ones that crumble to dust after ten to twenty years.
Related pages
- Alkaline battery Zinc powder and manganese dioxide either side of a potassium hydroxide paste, in a steel can.
- Smartphone screen Chemically strengthened aluminosilicate glass over a touch layer and an OLED or LCD panel, with an oil-shedding coating on top.
- Solar panel Doped silicon wafers with silver contacts, sealed between low-iron glass and a plastic backsheet in an aluminium frame.
- LED bulb Blue LED chips under a yellow phosphor, plus a driver circuit and a heat sink — and it is the driver that dies.
- Touchscreen A grid of transparent electrodes measuring the tiny capacitance your finger adds — which is why gloves fail.
- Computer keyboard ABS or PBT keycaps over either a silicone rubber dome on printed film, or individual mechanical switches.
- Headphones A neodymium magnet, a coil of copper wire and a thin plastic diaphragm — a loudspeaker shrunk to fit an ear.
- Computer mouse An ABS shell around a tiny camera taking thousands of pictures a second, plus two clicky microswitches and PTFE feet.
- Pencil Stationery and paper
- Tennis ball Sport and games
- Banknote Around the house
- Golf ball Sport and games
- Paper Stationery and paper
- Glass Building materials
Sources
- Typical range compiled from manufacturer specifications — At One Place