Volume and port area recommendations?

[Jonnyswboy]

Designing a box for 2x Fi SSD 18s and am not sure what volume/port area to use. Tuning to about 38hz and plan on ~14ft3 net.

Fi recommends 100in2 for both but that seems low to me. WinISD and speakerboxlite are giving me completely different port velocity numbers so that isn't helping. My gut says two 8" aeroports would be good.

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[SlugButter]

2 8 inch aeroports should work fine. On a slot port 100 is too small I think. 12-16 inches per cube is a good rule.

 

[hispls 5,000+ posts]

Designing a box for 2x Fi SSD 18s and am not sure what volume/port area to use. Tuning to about 38hz and plan on ~14ft3 net.

Fi recommends 100in2 for both but that seems low to me. WinISD and speakerboxlite are giving me completely different port velocity numbers so that isn't helping. My gut says two 8" aeroports would be good.

I have not personally had great luck with multiple round ports vs single ports but I've seen others do well with them. I would also be looking for a lot more port area especially if you plan to throw some power at this.

 

[Jonnyswboy]

I have not personally had great luck with multiple round ports vs single ports but I've seen others do well with them. I would also be looking for a lot more port area especially if you plan to throw some power at this.

Planning on clamping 3k. I'd go for a single 12" but I can't source one afaik.

 

[Bobbytwonames 5,000+ posts]

Designing a box for 2x Fi SSD 18s and am not sure what volume/port area to use. Tuning to about 38hz and plan on ~14ft3 net.

Fi recommends 100in2 for both but that seems low to me. WinISD and speakerboxlite are giving me completely different port velocity numbers so that isn't helping. My gut says two 8" aeroports would be good.

It sounds like you need about 200 sq. inches. Maybe they meant 100 sq. inches each and not total?

 

[Jonnyswboy]

It sounds like you need about 200 sq. inches. Maybe they meant 100 sq. inches each and not total?

 

[Jonnyswboy]

Both 2 8" ports (100in2), same length, volume, power, t/s, etc.

WinISD

Speakerboxlite

 

[Bobbytwonames 5,000+ posts]

View attachment 38013

I just asked my box builder friend. He's knows Scott the Fi owner real good and has installed a lot of Fi subs.

 

[Bobbytwonames 5,000+ posts]

View attachment 38013

7.1 sq. inches per cube seems awfully small. I would guess 170 sq. Inches at a minimum.

 

[Jonnyswboy]

7.1 sq. inches per cube seems awfully small. I would guess 170 sq. Inches at a minimum.

That makes sense to me, especially when looking at WinISD. But also people run a single 8" port on (2) 12s all the time and and I imagine one of these 18s is somewhat comparable to (2) 12s. Also aeroports can be a bit undersized, maybe 100in2 of aero would perform like 150in2 slot? I'm totally lost on this one lol. I am very interested what your box builder friend says.

 

[Bobbytwonames 5,000+ posts]

That makes sense to me, especially when looking at WinISD. But also people run a single 8" port on (2) 12s all the time and and I imagine one of these 18s is somewhat comparable to (2) 12s. Also aeroports can be a bit undersized, maybe 100in2 of aero would perform like 150in2 slot? I'm totally lost on this one lol. I am very interested what your box builder friend says.

Did you tell Fi how big your box is? A 2 - 12's box equals around a 1 - 15 box to me. A 2 - 15's box is pretty close to a single 18, give or take and obviously sub dependent. One 12" aeroport might work (113 sq. inches).

 

[Jonnyswboy]

Did you tell Fi how big your box is? A 2 - 12's box equals around a 1 - 15 box to me. A 2 - 15's box is pretty close to a single 18, give or take and obviously sub dependent. One 12" aeroport might work (113 sq. inches).

I would if I could get one for a reasonable price. Sonotube seems like the only option but I don't want to add a flare.

 

[Bobbytwonames 5,000+ posts]

I would if I could get one for a reasonable price. Sonotube seems like the only option but I don't want to add a flare.

Did Fi know that you wanted sq. inches for an aeroport?

 

[Bobbytwonames 5,000+ posts]

I would if I could get one for a reasonable price. Sonotube seems like the only option but I don't want to add a flare.

Her ya go. Now this is for slot port. You are the "just some guy online."

 

[Jonnyswboy]

Did Fi know that you wanted sq. inches for an aeroport?

I did not specify.

Her ya go. Now this is for slot port. You are the "just some guy online."

View attachment 38021

Bless you.