Speakerman

I have 3 Image Dynamics 12's and 3 Jbl amps. The install that i have right now is no where near the best that i can do. I'm designing a new enclosure and need to figure the tuning frequency. I'm making the port removable so that i can listen to deep pounding bass when i'm cruisin the strip and then pull it out and swap another in so i can tear up the mike at comp. Its a single chamber and single port. the max opening deminsions are 8" x 21.5". The max enclosure volume w/out port is 8.547 ft^3, minus .12 ft^3 per sub. I want 2 different ports. one at 25herts and another at 55-60 herts. It can only be 13inches deep max. I have used many online programs to figure this out and i have had no luck with them. All come out to unrealisticly huge numbers for the depth. Could somebody help me out here. getting angry:banghead: ready to go crazy [img]graemlins/gunsarecool.gif[/img]

pinhead

in order to reduce port lenght you can only do these things
1 increase box size
2 decrease port area
3 tune to a higher frequency
or a combination of all 3
you can also fold or put a right angle on your port

Speakerman

Yeah i totally forgot about being able to "bend" the port. Thanks for bringing that back to my reality. I want to try and keep the port opening as big as possible because this 8.5 cube box is right behind my eyes facing forward. And i cannot make my box bigger without crossing some serious boundaries.

Does the tuning frequency mainly come from the area inside the port?? Its not a combination of length width and hieght is it?

Jmac

Tuning Frequency depends on ...

Port area
Port length
Net internal volume

Lv = Av*1.84*10^8/[Vb*1728*(Fb/0.159)^2] - 0.823*sqrt(Av)
or
Fb = 0.159*Sqrt[Av*1.84*10^8/(Vb*1728*(0.823*Sqrt(Av)+Lv))]

Lv = Length of port in inches
Av = Port area in square inches
Vb = Net internal volume of enclosure in cubic feet
Fb = Tuning frequency of enclosure in hertz
Sqrt = Square root

[ August 04, 2004, 11:12 PM: Message edited by: Jmac ]