Port ?

[boris333]

How to calculater port size ? is there a program or a formula for it ?

 

[Collo]

Port calculator

there are plenty of programs. I like others on this forum like WinISD. Get it for free at http://www.linearteam.dk/

 

[simon5]

The formula is :

An externally hosted image should be here but it was not working when we last tested it.

 

[boris333]

ok i need to build a box that is about 16x35x25 or smaller ? for 4 infinity 1220 subs ... i wont it to be vented and tuned to about 40 Hz ? can some one help me with this.. is this a big enough box ? what size will the port be ? i just wont it to be loud

 

[BassAwdyO]

Four 1220w's. Those are the 12" reference subs with DVCs that look like the Kappa perfects arent they? For car I'd suggest at least 1 cubic foot per sub, and tuning around 30hz if we're talking about the same speaker.

Do you have the T/S parameters

 

[boris333]

Four 1220w's. Those are the 12" reference subs with DVCs that look like the Kappa perfects arent they? For car I'd suggest at least 1 cubic foot per sub, and tuning around 30hz if we're talking about the same speaker.

Do you have the T/S parameters

yes those are the subs that i have ... what is T/S parameters ? you say that i need 1 cubic foot pet sub so thats 4 cubic foot what is that in inches ? and how do i know what size of a port is 30hz ?

 

[BassAwdyO]

well you said you have 16x35x25inches which will give you around 8 cubic feet which should be pleanty.

Is this going in a car or house? For car I'd almost suggest sealed box because you're going to get a big boost from cabin gain and you really wont need a port at all(unless you're going for SPL) For home ported should work out nicely and you can tune between 20 and 30hz to your own tastes.

Tell me exactly what you want and I'll be able to give my best opinion. I used to own a pair of those subs. I ran them in 10cubic feet tuned to 20hz for HT and it wasnt a bad setup. Although now I have a Tumult in 6 cubic feet which goes down to 10hz and blows those subs out of the water!

 

[richie00boy]

Basic vent calculator on my website http://www.readresearch.co.uk click on the 'utilities' link.

 

[boris333]

well you said you have 16x35x25inches which will give you around 8 cubic feet which should be pleanty.

Is this going in a car or house? For car I'd almost suggest sealed box because you're going to get a big boost from cabin gain and you really wont need a port at all(unless you're going for SPL) For home ported should work out nicely and you can tune between 20 and 30hz to your own tastes.

this is going in to a car ... now i dont know what to tune it to 20 or 30hz ? u tell me .. or just go sealed ? if its sealed how big of a box do i need then ?

 

[BassAwdyO]

Go sealed. Use a box between 4-8 cubic feet. Anywhere in that range should work fine. I'd suggest going towards the larger end, but it wont make an incredable difference. Make sure when you build the enclosure that there are no air leaks. You can add acoustic stuffing or fiberglass insulation too if you have some handy.

 

[boris333]

thanks ......

 

[BassAwdyO]

let us know how it turns out!

 

[boris333]

You can add acoustic stuffing or fiberglass insulation too if you have some handy.

how much of fiberglass do i need ?

 

[richie00boy]

Just line the walls. If you fill the enclosure or obstruct the vent it will change the way the vent works.

 

[boris333]

my box has no vents... it is a sealed box

 

[michal]

Here's the 1220w specification. 1220W is a single voice coil 12" sub.

this is going in to a car ... now i dont know what to tune it to 20 or 30hz ? u tell me .. or just go sealed ? if its sealed how big of a box do i need then ?

Recommended volume for sealed enclosure is 1.25 cubic feet per driver. Larger box produces deeper bass, but makes it less tight (has greater group delay properly speaking).

I've recently have built a sealed enclosure with two Infinity Reference 1030w drivers and they sound ok. Just make sure your amplifier(s) match the sum of RMS power ratings of your subs and it will be loud.

how much of fiberglass do i need ?

1" on all walls except the one on which subs are mounted on.

this is going in to a car

Into a minivan or SUV? That's a large box you are going to have. Car size affects the way sub sounds (cabin gain / transfer function), if you want flat frequency response( same loudness for different tones) you need to take car size into account when designing sub enclosure, especially a sealed one.

 

[boris333]

what kind of a fiberglass do i need there are two kinds cotton and solid type .. the guy at the store tells me that i need the solid one ? is this correct ? this is in a hatchback car .. the box size is now 30x25x16 ..

 

[Volenti]

what kind of a fiberglass do i need there are two kinds cotton and solid type .. the guy at the store tells me that i need the solid one ? is this correct ? this is in a hatchback car .. the box size is now 30x25x16 ..

If you want to just line the walls get the solid type (compressed I assume?) if you want to fill the enclosure (ie-most of the airspace is occupied by fibreglass) use the cotton type.

Basically, filled is better for pure SQ, un-filled is better for max volume (will be around 3db louder at resonance un-filled)

Try it both ways, use what sounds best to you.

 

[mangrovejack]

Dacron pillow stuffing is the stuff you would normally use. I'm not sure I'd want fibreglass fibres being constantly bombarded with high speed airflow (aka the sub's cone movement) and possibly being passed out the port.

 

[richie00boy]

Apparantely now there is not vent. However, I totally agree with you on dacron/baf vs fibreglass. Fibreglass is just not nice.