port size vs length for 2 tens in a decently big box.

[Synastr]

Ok, so my box cft after subs is right around 3cft. i can build it less if need be. The subs are re pro sr series. ill list the specs. The question im after is, im porting it to run about 31-32 hz. i cannot decide on what port size to use or how many. im thinking either two 3" or one 4" possibly two 4". Ive never designed a ported box so im not 100% on how to tune the ports to it. they recomend 1cft per sub at 35hz but i want it to still go low but have a lot of punch to the bass.

a member on here recomended 2.5 cft and i can build from 1cft for both all the way up to 3cft.

Electrical Q Value -Qes 0.39

Mechanical Q Value -Qms 5.5

Total Speaker Q Value -Qts 0.36

Free Air Resonance -Fs 25.3 Hz

Equivalent Compliance -Vas 31 liters

One-Way, Linear Excursion -Xmax 18 mm

Efficiency -SPL 1W/1m 85.3 dB SPL

Effective Piston Area -Sd 310 cm^2

DC Resistance -Re 1.8 ohm

Nominal Impedance -Znom Dual 2 or 4 ohm

Thermal Power Handling -Pe(RMS) 320W

Force Factor -Bl 14.35

Click to read more...

 

[Synastr]

ok ive decided to build the box at 2.2 cft after sub displacment, to allow for room for my amp rack. now ive went to port caculaters and still need to know whether to use 1 or 2 ports. it says 1 3" port should only be 7.5 inches long and 2 should be about 16. does that mean two 7.5 port? or two 16 inch ports?

 

[slam 5,000+ posts]

I have a box at 2.14^3 tuned at 26hz and is 26.xx long. Believe its 2.5 x 8 x 26.xx

 

[Synastr]

im doing a round port though. and im tuning a little bit higher than that.