Ported Cone excursion

[actlsub]

Ive been playin around with winisd pro using a 12 brahma and im just wonderin y the cones excursion drops down low near the tunning freq of the box, even tho its looks like the system is most effecient at or just above the tunning freq.

[paikiah]

Originally posted by actlsub
Ive been playin around with winisd pro using a 12 brahma and im just wonderin y the cones excursion drops down low near the tunning freq of the box, even tho its looks like the system is most effecient at or just above the tunning freq.

ah, the magic of physics....

[crhye250r]

Enclosure fabrication is all dependent on the laws of physics and air flow. At tuning frequency, the cone excursion, in reality (not just on a program) is at its lowest. That makes it much more efficient, and is the reason you want to tune your box to the resonent frequency of your car. That is the reason a subs burp handling ability (when done correctly) is a question of thermal power handling ability, rather than mechanical. There are tons of variables to consider.

[actlsub]

ooo, good ****. so then even tho it will be hittin low in the 30's the cone movement wont even be that much because thats what its tuned too. Is the a place where they list resonant freqs for cars or u just got to test it for urself and see what works best.

[crhye250r]

There is a formula to figure resonent frequency, but i cant seem to locate on my crappy *** desk here..I had it written down. Maybe someone can help ya out with that. You have to measure the distance between the windshield and back window (if im not mistaking) and plug it into the formula.

[ShaunMac]

Measure from rear of vehicle to the firewall
in the front. Let that be X

Wave Resonance = 1130/X/2

1/4 Wave Resonance = 1130/X/4

Try both of these to determine which is loudest.

Example: if X = 8ft
1130/8/2 = 70.6Hz
1130/8/4 = 35.3Hz

[Wonderbread]

Originally posted by ShaunMac
Measure from rear of vehicle to the firewall
in the front. Let that be X

Wave Resonance = 1130/X/2

1/4 Wave Resonance = 1130/X/4

Try both of these to determine which is loudest.

Example: if X = 8ft
1130/8/2 = 70.6Hz
1130/8/4 = 35.3Hz

rear bumper?

[ShaunMac]

Originally posted by Wonderbread
rear bumper?

On the inside of the car. I don't think the outside
dimensions of a car have anything to do with sound
behavior inside the car.

Example: In a Single Cab truck measure from
the rear wall behind the seat to the firewall
up front.

[Wonderbread]

so in a car... back seat?
or rear deck?

[ShaunMac]

Rear deck.

Whatever point is farther back.

[Wonderbread]

right on