Max SPL calculation

[Guiria]

Is there a method (or theory) to calculate max SPL of driver inside a given enclosure? If so I'd like to know. If the answer is buy software X then I'd like to know that as well.

 

[avaserfi]

Is there a method (or theory) to calculate max SPL of driver inside a given enclosure? If so I'd like to know. If the answer is buy software X then I'd like to know that as well.

WinISD Pro Alpha is capable of doing so and is free. Just input the drivers T/S specs and model appropriately. Input the total power you will be using with the sub and choose the appropriate graph.

http://www.linearteam.dk/default.aspx?pageid=winisdpro

 

[jelanier]

Is there a method (or theory) to calculate max SPL of driver inside a given enclosure? If so I'd like to know. If the answer is buy software X then I'd like to know that as well.

The general formula is this:

8E-12 X Fs^3 X Vas/Qe (with Vas in in^3)

This represents the acoustic power output with 1 watt input.

Example:

Fs=20
Qe=.38
Vas=1728 (1 cubic foot)

P(1)=8E-12 X (20)^3 X 1728/.38 = 2.91E-4

Take the log of this and multiply by 10 to reference this to 1 acoustic watt.

Log(2.91E-4) X 10 = -35.36 db
1 acoustic watt is 120db
So 120-35.36=84.64 db spl

If you are using a 100 watt amplifier

log(100watts/1watt)*10=20db

84.64+20=104.64 Db

Note: this is sine wave..with music figure average sound pressure levels at full tilt to be about 10db down from this. Also every time you double your distance from the source, the level drops by 6db. (inverse square law)

Jim