I need some port length help for the "widgets"

[Wardsweb]

I don't have any modeling software and need to now how long to make the ports on these speakers. I'm hoping someone here will find this task easy.

Cabinet internal volume: 5.75 cu ft
Driver is an Altec 416-8C. The specs I found here: http://www.lansingheritage.org/images/altec/specs/components/416-8c/page1.jpg
Re:6.5 ohms
Fs:24.1 Hz
Qts:0.26
Qm:6.73
Qes:0.28
Vas:22.9 ft3
Vd:0.20 ft3

So with two 4" ports, how long should they be?
Thanks

[duaneage]

5.25" each tuned to 37.75 hz in 5.75 cu ft. This assumes no inductor , you going to be a little off if you have a inductor in the mix, maybe tuning them a little higher at 39 hz at 4.75 inches each might work better.

[duaneage]

graph here

[Mr. Widget]

I am only casually familiar with that woofer, but I'd guess at around 38Hz too for a good tuning. Using BB 6 Pro I get a port legnth of ~3.5" for the pair of 4" ports.

I sent you (4) 11" ports so I guess you could make up a pair at 5" and a pair at 3.5" and compare them.


Widget

[Steve Gonzales]

Hey Wardsweb,

You gettin' those 416-8C's from GPA?. Best kept secret this side of epay don't ya think? $400 bucks a pair for BRAND NEW, CORRECT woofers! :p

[Wardsweb]

Hey Wardsweb,

You gettin' those 416-8C's from GPA?. Best kept secret this side of epay don't ya think? $400 bucks a pair for BRAND NEW, CORRECT woofers! :p

Actually, these came out of my A7's along with the 802-8G drivers and 511B horns. These mounted in the new cabinets will be my main 2 channel rig in the living room. AHHH vinyl, tubes and horns...gotta love it.

[Wardsweb]

Duaneage and Widget - thank you very much for the help. I will make up a couple pair and see how they sound to me. Thanks again.