Home Speaker Asylum

General speaker questions for audio and home theater.

RE: I would guess the op is wanting the watts he is using at the level he describes.

hahax said " Doubling that [distance] reduces the level by 1/4 on most speakers"

Yes, but only if they are in an anechoic chamber or outdoors.

If they are in a room then the SPL will remain constant with distance once the listener is far enough back to be in the reverberate field.

In a "typical" living room this happens at about one meter (how convenient).

A quote from Paul Jappa,

"The calculator you linked assumes you are listening outdoors, or at least in a concert-hall or larger space.

In the average living room using average speakers, the sound level does not reduce with distance once you are past about 1 meter. This is because the reverberant field in the room has statistically uniform loudness; only the direct field drops off with distance. At about 1 meter the direct field is the same loudness as the reverberant field; beyond that point the reverberant field dominates the perceived loudness.

This has of course some variation, depending on the room's size, sound absorbing contents, and speaker directivity index. The subject of room acoustics is fairly complex and challenging, but quite rewarding to study if you are a music enthusiast. But until you are ready to do a full study of your environment, the 1-meter rule is a good place to start. Just re-do the calculation with 1.0 meters distance instead of 4.5 meters. The difference will be startling, around 1/20th as much power is needed."

Have Fun and Enjoy the Music
"Still Working the Problem"

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