Member Avatar for rt7878

I just really want to know what goes on inside a speaker. because i dont understand how my subwoofer can pump so much air out of it without using a fan

anyone know?

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asked why a sub can "pump" a lot of air without a fan. Building on points from , and , the diaphragm of a speaker works like a piston: it creates alternating regions of higher and lower pressure (compressions and rarefactions) that propagate as sound rather than producing a one-way wind. Low-frequency drivers have large area and long excursion, so the instantaneous air volume they move each stroke can be substantial and sometimes visible. See Loudspeaker and Sound wave.

Two simple quantities let you quantify "how much air" is moved. Sd is the effective cone area and Xmax is the peak excursion. Peak volume displaced is V_peak = Sd × Xmax. The acoustic volume flow (volume velocity) depends on cone velocity; for a sinusoid x(t)=Xmax·sin(ωt) the RMS volume velocity is Urms = Sd × ω × Xmax / sqrt(2), where ω = 2πf. Example calculation:

12 in woofer: Sd ≈ π·(0.1524 m)^2 ≈ 0.073 m^2
Xmax = 0.01 m (10 mm) -> V_peak = 0.073 × 0.01 ≈ 0.00073 m^3 ≈ 0.73 L

Enclosure and porting change how that motion turns into audible SPL and visible airflow. A bass‑reflex (ported) box uses the port as a second radiator near its tuning frequency; the port can visibly move air and will behave very differently if blocked, increasing cone excursion and distortion and risking mechanical stress to the surround/spider. See Bass reflex.

Practical notes: check Sd and Xmax on specs when choosing a sub; avoid amplifier clipping (it forces drivers to max excursion and can damage them); if a port "chuffs" at high output, add flares or change tuning rather than restricting flow.

Recommended Answers

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Member Avatar for 4th&3wood

If you are talking about a convention cone type speaker take the dust cover off of the speaker and look at how the cone travels back and forth. I've blown out candles to demonstrate the amount of air it moves.

Member Avatar for jermaghs07

small surges of current travel through the voice coil which moves the "cone" Producing sound waves. the cone traveling is what produced the air movement

Member Avatar for bobbyraw

because the cone of the speaker vibrate depending on the about of wattage that is applied to the coil that surrounds a magnet. this displaced air help the speaker to perform better. if the Air hole was blocked the sound would be distorted and can tear the rib of the speaker cone (Rib is the flexible material that attached the cone to the frame of the speaker.)

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