Help decide 2x 12" Fi Q's or single?

[lyons238]

So I currently have a 2013 Subaru WRX with some work done to it. What I have...

- 2x 12" Fi Q's (but my friend wants to buy one)

- dcpower 250a alt

- 1x Sundown SCV-2000

- 1x D3400 batt

- 1x XP2500 batt

This is all perfect to run 1x Q. If I run two I would need...

- XP2500 second battery

- Sundown SCV-2000 amp strapped

Also in order to fit the two subs the box specs would be 4 net cubes, 32hz, but only 9.9 sqin port area per cuft or around 37sqin port area. So the port area is not ideal, is this far to small? My designer thinks it will be fine but I'm not so sure.

If I ran a single Q I could get perfect box specs without any sacrifices besides the output of having a second woofer. Being that it's a Subaru and not a competition vehicle, do you all think I would be better off running the single or dual Q's? Running two subs would put close to 300lbs in my trunk, take up the entire thing, cost more money, and leave me with no spare tire or room in the trunk. If I run a single Q it will only be about 160lbs so 150lbs lighter. I'm coming from a single AQ HDC3 15" in a ported box off 1500w in a single cab truck and I was more than happy with the output. Will the single Q likely satisfy me or should I stick with the original plan and run two?

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[Jeffdachef 5,000+ posts]

Go aeroported if you are tight on space, they should work fine on much less port per cube.

 

[lyons238]

Go aeroported if you are tight on space, they should work fine on much less port per cube.

If I run an aeroport I would have to side fire it and it would have to be 28" long when my box is only 32" wide, so internally it's only 30.5", so 2.5" would not be adequate space for proper port flow, and I can't move the port external cuz it's already firing right into the side walls of the trunk.

Unless I ran 3x 4" aeros that are 22" long which would be abot 38sqin of port or 9.5 per cuft, which should just cut it being an aeroport.

However how do I figure out the total displacement of 3x 4" aeros with flares and 22.8" long assuming that's the correct size for the tuning

 

[Dmac1991]

1 12 or two 10s

 

[Jeffdachef 5,000+ posts]

If I run an aeroport I would have to side fire it and it would have to be 28" long when my box is only 32" wide, so internally it's only 30.5", so 2.5" would not be adequate space for proper port flow, and I can't move the port external cuz it's already firing right into the side walls of the trunk.

There's a method to get long aerport lengths in limited space.

here is how its done and just in case you cant access the page, i'll post the info on here too

long round ports in small enclosures - Car Audio Classifieds

Below is an explanation on how DSS gets a 37.25 inch long round port in a box 24 inches deep without using elbows.

For this demonstration I'm using a 6 inch round port with a external diameter of 6.5 inches and a internal surface area of 28.25 inches.

Steps involved for calculating port.

1. How far away to make the end of the port form the back wall. (No it's not the diameter of the port). The port area is 28.25 inches so we need the area between the port end and back wall equal or a tad more than the port area. So surface area of a cylinder is...

area = (2pi x radius) x height

since we know the area...

28.25 = (6.28 x 3) x height

1.49= height (distance from port end and back wall)

Next a port extension is needed with an Inner Diameter that will create a surface area of 28.25 inches between the port and the port extension. I use sketch-up as it takes much less time than doing it by hand. In this case a port extension with a 9 inch ID works well.

Finally the port extension length is calculated like any other slot port extension to create the needed 37.25 inches of total port length.

Port length is calculated by an imaginary line in the center of the width of the port. So just draw a line between the port walls and measure snaking around all the way to the end. Effective port length of a flared end varies depending on the rate of the flare but most of the time the point 1/2 the distance from the throat and mouth is used. So if you lay a flare on a table with the throat (the part that mounts to the port) on the table and measure it's "depth" and its 6 inches then the flare effectively adds three inches of length to the port.

 

[lyons238]

There's a method to get long aerport lengths in limited space.
here is how its done and just in case you cant access the page, i'll post the info on here too

long round ports in small enclosures - Car Audio Classifieds

Below is an explanation on how DSS gets a 37.25 inch long round port in a box 24 inches deep without using elbows.

For this demonstration I'm using a 6 inch round port with a external diameter of 6.5 inches and a internal surface area of 28.25 inches.

Steps involved for calculating port.

1. How far away to make the end of the port form the back wall. (No it's not the diameter of the port). The port area is 28.25 inches so we need the area between the port end and back wall equal or a tad more than the port area. So surface area of a cylinder is...

area = (2pi x radius) x height

since we know the area...

28.25 = (6.28 x 3) x height

1.49= height (distance from port end and back wall)

Next a port extension is needed with an Inner Diameter that will create a surface area of 28.25 inches between the port and the port extension. I use sketch-up as it takes much less time than doing it by hand. In this case a port extension with a 9 inch ID works well.

Finally the port extension length is calculated like any other slot port extension to create the needed 37.25 inches of total port length.

Port length is calculated by an imaginary line in the center of the width of the port. So just draw a line between the port walls and measure snaking around all the way to the end. Effective port length of a flared end varies depending on the rate of the flare but most of the time the point 1/2 the distance from the throat and mouth is used. So if you lay a flare on a table with the throat (the part that mounts to the port) on the table and measure it's "depth" and its 6 inches then the flare effectively adds three inches of length to the port.

I'll have to look more into, though to snake an 8" aeroport around inside my box will be difficult.

If I use 3x 4" aeros how would I calculate the displacement of those? And how would j get the correct length since in order to know the length I need to know the net box volume, but in order to know the net box volume I need to know the displacement of the aeroport, unless the psp calculator accounts for its own port displacement, does it?

 

[Jeffdachef 5,000+ posts]

I'll have to look more into, though to snake an 8" aeroport around inside my box will be difficult.
If I use 3x 4" aeros how would I calculate the displacement of those? And how would j get the correct length since in order to know the length I need to know the net box volume, but in order to know the net box volume I need to know the displacement of the aeroport, unless the psp calculator accounts for its own port displacement, does it?

use torres box calculator instead, it does all that for you. Much more accurate IMHO

 

[lyons238]

use torres box calculator instead, it does all that for you. Much more accurate IMHO

Thanks man! I'm still leaning towards a single 12 to save weight and money. But if I can get a rock solid design for the 2x Q's I'll roll with that.