Judge this Port please

[bondj0007 10+ year member]

for a vented enclosure of volume: 56.21litres or 1.985cubic ft

i will have the following PORT/VENT:

Port Area: 14.77 sq.inches

Port Length: 17.69 inches

Port Volume: 0.1512 cu.ft

i found it using: http://www.carstereo.com/help2/Articles.cfm?id=31

Would this be a good port???

thanks

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[bondj0007 10+ year member]

someone please guide me

 

[ALHII303 10+ year member]

What are you trying to tune to?

 

[bondj0007 10+ year member]

tuning to 31Hz

 

[matrxx dude 5,000+ posts]

must be a 12

 

[ALHII303 10+ year member]

From winisd it says it would tune to about 30.77 Hz. So yes it does sound correct

 

[bondj0007 10+ year member]

it is a 12 inch pioneer

but what is the ideal port area for my box??

if i know the area then i can find the length easily

 

[bondj0007 10+ year member]

what i dont understand is:

if i find a port size that using that size my box adequately tunes to the wanted frequency, is that a correct size??? or that size could be small or big, according to my box volume independantly from what i am tuning???

 

[tommyk90 5,000+ posts]

14 square inches of port area is a tad small for a 2 cube box.

What model pioneer is going in it?

What amp are you using?

 

[matrxx dude 5,000+ posts]

yeah i was thinking more like 30 sq inches

 

[bondj0007 10+ year member]

sub: http://www.pioneer.eu/eur/products/25/130/201/TS-W307D2/index.html

Amp: http://www.kenwood-electronics.co.uk/products/car/amplifiers/KAC-6203/details/

WHAT I WANT TO KNOW IS HOW YOU CALCULATE A PORT AREA FOR A SPECIFIC VOLUME??

i.e. how you say its a bit small??? if i increase port area, then i should increase port length to tune it the same as previous port area and length, SO what will be the difference?

 

[tommyk90 5,000+ posts]

sub: http://www.pioneer.eu/eur/products/25/130/201/TS-W307D2/index.html
Amp: http://www.kenwood-electronics.co.uk/products/car/amplifiers/KAC-6203/details/

WHAT I WANT TO KNOW IS HOW YOU CALCULATE A PORT AREA FOR A SPECIFIC VOLUME??

i.e. how you say its a bit small??? if i increase port area, then i should increase port length to tune it the same as previous port area and length, SO what will be the difference?

A general rule of thumb is 10-15 square inches of port area for every cubic foot of airspace.

So for your enclosure size, i would go with at least 20 square inches. 25 would probably be better.

And yes, if you increase port area, you will have to make it longer to lower the tuning back down.

 

[skateboardkid 10+ year member]

you want rmore like 14-16 inches per cubic foot if im not mistaken.

see if you can get that to work.

Port area is pretty dependent on overall box size so for a 2 cube box 28 inches of port area is bout ideal for a vented box.

Read here this does apply to most ported systems,

http://www.ddaudio.com/dd/caraudio/enclosureInfo/boxSize_hiEff.asp

they want you tune higher at 40Hz but if you know you want 31Hz just do the math from there on your length.

good luck bro.

This is just my suggestion though most will agree.

 

[bondj0007 10+ year member]

thanks all for the info

ill go with bigger port for my box as you suggested, and then i tune it to 31Hz through port length

cheers

 

[Immacomputer 10+ year member]

The DD port area per cubic foot of volume is only to keep things simple for the average Joe who knows nothing about box design.

It is NOT a rule of thumb for every driver out there. I have used some 8" subs that worked really well in a 3 ft^3 enclosure but they sure as hell wouldn't like 45in^2 of port area. It would be too much and waste a ton of space. A pair of them were perfectly fine with about 20in^2 of port area in 5 cubes. Great "rule of thumb" that is.

With that particular sub, I would do about 20-30in^2 though. You could stay around 20in^2 and you should be fine.