ToolsElectronics, cables & data
Loudspeaker sensitivity, efficiency & max SPL
Maximum SPL from sensitivity, amplifier power and distance; sensitivity ↔ efficiency; 2.83 V vs 1 W specs.
Maximum SPL at a distance
dB SPL
Ω
W
m
Maximum SPL at the listener
98.01dB SPL
SPL at 1 m (one box)
118dB SPL
Sensitivity normalised to 1 W
95dB
Sensitivity ↔ efficiency
dB SPL
%
Free-field estimate: +3 dB per doubling of power, −6 dB per doubling of distance, +3 dB per doubling of boxes (incoherent). Real systems lose a few dB to power compression and gain some from room reflections. 2.83 V equals 1 W only into 8 Ω.
How it works
Sensitivity is the SPL a loudspeaker produces at 1 m with 1 W. Every doubling of power adds 3 dB; every doubling of distance takes 6 dB away. Most loudspeakers convert only around 1 % of the electrical power into sound.
Formulas
- SPL = S + 10 · log₁₀ P − 20 · log₁₀ d + 10 · log₁₀ N
- S ≈ 112 dB + 10 · log₁₀ η
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