Work out how loud a box gets at a distance from its sensitivity and power, and whether you have headroom over your target SPL. Updates live as you type.
How loud a box gets at a distance, and whether you have headroom.
SPL = sensitivity + 10·log₁₀(W × boxes) − 20·log₁₀(distance). Inverse-square loss only; ignores air absorption & room gain.
Work out how loud a box gets at a distance from its sensitivity and power, and whether you have headroom over your target SPL. Updates live as you type.
Start from the speaker sensitivity (dB at 1 watt, 1 metre), add 10·log10 of the power in watts (and the number of boxes), then subtract 20·log10 of the distance in metres. That last term is the inverse-square law: level drops about 6 dB every time the distance doubles.
Sensitivity is how loud a speaker plays with 1 watt of input measured 1 metre away, in dB SPL. A typical passive PA top sits around 96 to 99 dB; higher-sensitivity boxes need less amplifier power for the same level.
No. It is free-field inverse-square only, so it ignores room gain, reflections and air absorption. Indoors you will usually measure a few dB more than this; over long throws outdoors, a little less. Treat it as a planning starting point, not a certified measurement.
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