PDA

View Full Version : Port Area Question



O.G. D-Wet
04-09-2010, 12:59 PM
Please don't flip $hit at this question as I'm sure it's been asked before... Everytime I search something on here I get zero results for some reason so here it goes...
Say I'm building a ported enclosure using PVC for ports... does it matter if they are thin and long vs, short and wide as long as the area is the same? There has to be a difference in subwoofer performance, right? I've seen boxes with very long narrow ports and I've seen them with HUGE massive ports the same diameter of the sub itself almost lol So what's the difference?

O.G. D-Wet
04-09-2010, 01:55 PM
??? anyone?

O.G. D-Wet
04-09-2010, 03:01 PM
???????????

RAM_Designs
04-09-2010, 07:17 PM
Port area refers to the cross sectional area of the port, most commonly 4", 6", etc. In order to determine how long a port needs to be, there are 3 things that need to be determined.

1) box volume
2) desired tuning frequency
3) number of ports and how big they are

Change any of those things and port length will change as well.

O.G. D-Wet
04-09-2010, 08:58 PM
Port area refers to the cross sectional area of the port, most commonly 4", 6", etc. In order to determine how long a port needs to be, there are 3 things that need to be determined.

1) box volume
2) desired tuning frequency
3) number of ports and how big they are

Change any of those things and port length will change as well.

Kool... but what I'm wondering is this... say i built the ideal sized box ported for a sub... say the port is suppose to be 3" in diameter and 4" long... Would it make a difference to change it to 4" diameter and 3" long? BTW I realized i said area whan I guess I mean volume lol srry bout that

bubbagumper6
04-09-2010, 09:04 PM
Kool... but what I'm wondering is this... say i built the ideal sized box ported for a sub... say the port is suppose to be 3" in diameter and 4" long... Would it make a difference to change it to 4" diameter and 3" long? BTW I realized i said area whan I guess I mean volume lol srry bout that

The difference is the port area. Generally for slot ports you want between 12-16 sq inches per cube of net volume. For round ports this number can get lower, usually it's like 6-8 for Aero ports but PVC=Aero ports so you'd probably be somewhere in between. The idea is that you want enough port area so you don't get port noise, but not too much.

O.G. D-Wet
04-09-2010, 09:11 PM
hmmm

luv2shrOOm
04-23-2010, 10:41 PM
op i get what u're sayin'... i was just tryin to figure this out my self...
my ports are 29" each and i'm tuned to 31hz.. i've seen a single square port 15"x13.5" with the same port area i have and just the one port was 26" or so with
same tuning..31hz

O.G. D-Wet
04-24-2010, 01:49 AM
op i get what u're sayin'... i was just tryin to figure this out my self...
my ports are 29" each and i'm tuned to 31hz.. i've seen a single square port 15"x13.5" with the same port area i have and just the one port was 26" or so with
same tuning..31hz

Yea... idk wtf imdoin wen it comes to aeros... seems like everyones always got their own 'rules' bout em. love ur ava and name btw... mushrooms ftmfw!

luv2shrOOm
04-24-2010, 03:40 PM
thx...mabey somebody can give opinions on what works best??
my box is pretty loud but the ports take up a ton of airspace.
i've seen a few steve mead boxes that have just one short port and his $hits beatin'.

mazdakid
04-24-2010, 03:45 PM
Kool... but what I'm wondering is this... say i built the ideal sized box ported for a sub... say the port is suppose to be 3" in diameter and 4" long... Would it make a difference to change it to 4" diameter and 3" long? BTW I realized i said area whan I guess I mean volume lol srry bout that

yes it would make a difference, youd be adding port area and shortening it, it would tune your box higher.

RAM_Designs
04-24-2010, 04:12 PM
As far as how much port area you should use for slots/aeros/pvc, tuning plays a role as well. Lower tuning requires less port area to keep port velocity at a reasonable level. So, given the same size box/port, a lower tuned box will have the lower port velocity. PVC ports are not aeroports, but they are smoother than MDF and have the lowest internal surface area possible since they are cylinder shaped, so you can generally get away with slightly less port area than a normal slot port.

What I normally go by, depending on tuning frequency.
mdf slot: 12-16in^2 per ft^3
pvc: 10-12in^2 per ft^3
aeros: 6-9^2 per ft^3

Jaredturp
04-24-2010, 05:34 PM
You are a bit off base.

RAM_Designs
04-24-2010, 06:47 PM
You are a bit off base.

On what, exactly?

Fuknmovin
04-24-2010, 07:02 PM
Check it,
The port area of a PVC port is ONLY the area across the face of the port as an example, it you have a 4" port, the ONLY number that effects the "port area" is the number 4. a 4" port has 12.5" of port area NO MATTER WHAT LENGTH IT IS. Length does not effect the port area, it ONLY effects the tuning. So you can not swap the length for the diameter of a port. Period. You need to check the tuning and make the length match the tuning you want. HOWEVER if you change the diameter of the port, you WILL change the tuning because different port diameters require different lengths to achieve the same tuning....

Or you can have me design the box for you and not worry about it!

Jaredturp
04-25-2010, 02:02 AM
Wasn't talking to you Ryan haha. He is saying that smaller pvc will need to be longer and that's not the case.

RAM_Designs
04-25-2010, 03:15 AM
Wasn't talking to you Ryan haha. He is saying that smaller pvc will need to be longer and that's not the case.

Ah, just making sure. I was confused and read over my post a few times because of it, haha.

Jaredturp
04-25-2010, 03:17 AM
Yeah, with a smaller port aka less port area you need less length to achieve a decent tuning. @OP