Port Tube Volume (Does it get Subtracted?)

[chibahawk 10+ year member]

Okay, when making a ported box.. if I have a rec. volume of 1.85cu.ft. and this is after I minus .084cu.ft. for the displacement of my sub.. do I also minus the volume of a port tube? Or am I aiming for 1.85 before installing the port?

Click to read more...

 

[DBfan187 5,000+ posts]

1.85cF is your NET volume after all displacements.

 

[tRiGgEr 5,000+ posts]

Subtract the displacement of the port also. So you need 1.85 after the driver and port displacement.

 

[chibahawk 10+ year member]

okay thanks.. do the aero ports come with a printed volume or where will i find the formula for that?

yea and ive taken calculus but ill always be lost in math so gimme a break

 

[tRiGgEr 5,000+ posts]

R x R x 3.14 x Length/1728 = displacment.

R = Radius

 

[chibahawk 10+ year member]

thanks.. is there a site other then the12volt.com that i might use for formulas?

 

[tRiGgEr 5,000+ posts]

http://www.carstereo.com/help2/Articles.cfm?id=31

http://www.carstereo.com/help2/Articles.cfm?id=21

 

[helotaxi 5,000+ posts]

R x R x 3.14 x Length/1728 = displacment.
R = Radius

Doesn't really help with figuring the displacement of the aeroport with the compound curve, but I doubt the tiny bit displaced by the flange will affect the tuning freq by a measurable amount.

 

[chibahawk 10+ year member]

okay question now.. on the formula sheet that advises the MINIMUM Port Diameter Size it's saying that I shouldn't go lower then 4.61 inches.. Don't most people use 4in. D ports though?

Should I find a 5"?

 

[DBfan187 5,000+ posts]

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=268-352

then use this calculator - http://www.psp-inc.com/psp-inc.com/public_html/..%5Ccgi-bin%5Cport_length_calculator.cgi

 

[chibahawk 10+ year member]

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=268-352
then use this calculator - http://www.psp-inc.com/psp-inc.com/public_html/..%5Ccgi-bin%5Cport_length_calculator.cgi

yea uh thanks?

 

[helotaxi 5,000+ posts]

Either go up to 5" (don't remember having ever that size PVC tthough) but that will eliminate the use of an aeroport, go with 2 4" or 3 3" ports with aeroports or go to a slot port.

 

[chibahawk 10+ year member]

ok i was just wondering how many people actually deal with port noise because that was what the formula addressed..

i'd like to only have one round port, and might do a slot port but that could be confusing because I've got a crazy enclosure plan up my sleeve basically

 

[helotaxi 5,000+ posts]

Have you ever heard port noise? It is REALLY annoying and messes up the tuning at higher power.

 

[chibahawk 10+ year member]

no i've actually never heard port noise but all I know is it factors into some peoples boxes.. port noise definitely sounds like somethin I wanna avoid and that calculator says that using a 5" port is key to avoiding it