Box Tuning ?

[Life is an Enigma]

I have a prefab box that i'm try to figure out the tuning of it. It has a weird two sized port the first port size is H-11.3/4 X W-13 X D-1.3/4 then it ports into H-11.3/4 X W-13 X D-4.0 inches.

The box is 1.12 CF size H-13 W-11 D-13.1/2 with the port the Width of the box is 19 inches. This is inside measurement the wood is 3/4 MDF.

 

[TBTL]

Close off the woofer opening, blow across the port and record the sound. Then FFT the signal to obtain the frequency.

 

[richie00boy]

Very odd design. I'd run an impedance sweep. In my Thiele-Small measurement guide on my website I show you how to determine Fb and QL (section 4.5)

 

[bentoronto]

Close off the woofer opening, blow across the port and record the sound. Then FFT the signal to obtain the frequency.

Brilliant idea. But does it work? Can show panel resonances? Can you post a plot?

Anybody have details on how it might be done best, like with driver in place or like with a pulse (explode balloon, cricket clicker, or firecracker)???

I never thought of testing my room that way. Too bad we have no psychoacoustics sub-forum.

B.

 

[weltersys]

I have a prefab box that i'm try to figure out the tuning of it.

An easy way to determine Fb is to do a sine wave frequency sweep, the speaker's excursion minima when sweeping up will be at Fb.
Painting a white dot near the cone edge makes it easier to see the movement.