Is xmax directly related to port area?

[MyFartsStink 10+ year member]

try like 80-100 of port and see what sounds like...and no, its not that easy to just change the port on an already constructed box

//content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif Time to sell it to a hood rat for 100

 

[amartin_72]

Does anyone know a rule for port area then or what?

 

[MyFartsStink 10+ year member]

Does anyone know a rule for port area then or what?

Ive read somewhere that more port length gives the sub a flatter response

Edit: lol never mind you said area

 

[amartin_72]

Yes a longer port yields lower tuning resulting in flatter response, but the ultimate unanswered question is when you have a sub, and know the paramaters, what the FU*ck do you do for port area?

 

[bonesninja 5,000+ posts]

Does anyone know a rule for port area then or what?

here's a decent port calculator....it sometimes looks a bit on the high side but i've never had an issue with the calculations when the box was finished

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

 

[newusername 10+ year member]

No, Xmax is not directly related to port area. It is a bit more complicated than that.

As far as rules are concerned, the 12-16 square inches of port for every cubic foot of volume works well for most. Obviously things change a bit with your application but this is maybe the best general rule.

A longer port may mean a lower Fb but it doesn't mean flatter response.

 

[amartin_72]

devildriver thanks for your help it seems like your one that at least has an idea whats going on. how can you say that 12 to 16, which is a big variance, can still be the rule, thats no rule. What determines wether we choose 12 14 or 16? I know given the same sub cu ft and tuning changing from 12 to 16 will have a dramatic effect on the output but how can we be guided before we design the box?

 

[MyFartsStink 10+ year member]

No, Xmax is not directly related to port area. It is a bit more complicated than that.
As far as rules are concerned, the 12-16 square inches of port for every cubic foot of volume works well for most. Obviously things change a bit with your application but this is maybe the best general rule.

A longer port may mean a lower Fb but it doesn't mean flatter response.

Sorry im still noobish for making boxes. Whats fb? frequency?

 

[amartin_72]

Im always guessing between 12 to 16 but how can i KNOW?

 

[bonesninja 5,000+ posts]

Sorry im still noobish for making boxes. Whats fb? frequency?

i believe its the resonant freq of the enclosure

 

[MyFartsStink 10+ year member]

i believe its the resonant freq of the enclosure

hmm Is there any way to determine the resonant frequency? Is it just the same as the tuning?

 

[newusername 10+ year member]

devildriver thanks for your help it seems like your one that at least has an idea whats going on. how can you say that 12 to 16, which is a big variance, can still be the rule, thats no rule. What determines wether we choose 12 14 or 16? I know given the same sub cu ft and tuning changing from 12 to 16 will have a dramatic effect on the output but how can we be guided before we design the box?

From 12-16 square inches is not a big difference unless you're using a high displacement driver with an enclosure that results in a port velocity that would be higher than normal...thus requiring the use of more port area.

Sorry im still noobish for making boxes. Whats fb? frequency?

Fb is what many call a "tuning" frequency.

 

[amartin_72]

Wow that link is alot of help! Thank you I think I will use that for a good starting point on my boxes.

 

[amartin_72]

So say if your going for SPL or sound quality would anyone safely say that more PA is going to yeild more spl but less clarity? Also would more port area increase the boominess of a ported box?

 

[MyFartsStink 10+ year member]

From 12-16 square inches is not a big difference unless you're using a high displacement driver with an enclosure that results in a port velocity that would be higher than normal...thus requiring the use of more port area.


Fb is what many call a "tuning" frequency.

Ok but I dont see how people have port lengths that are about 5 ft when someone can have the same tuning at a shorter length. I read that it is for a flatter responce but like I said Im still a noob at boxes and want to learn.