Port Help!!!

[swanginfleet]

I made a box for an 18" Fi Bl in an escort Wagon and I totally neglected one the main principles of a ported box. I only have 7sq in per cf. It sounds good around the mid 30s but it lacks big time on the lows. I tried making the port to volume ratio but I can't get the port to be around 32hz. Any ideas how to fix it without having to redo everything? Thanks in advance.

Wood Thickness - .75 inches

Displacements - .33 cubic feet

Frequency - 32.01 hz

Box Length - 21 inches

Box Width - 38 inches

Box Height - 18 inches

Port Length - 14 inches

Port Width - 11 inches

Port Height - 4 inches

Gross Volume(Feet) - 6.8 ft³

Gross Volume(Litres) - 192.55 L

Net Volume(Feet) - 5.94 ft³

Net Volume(Litres) - 168.12 L

Port Displacement(Feet) - 0.53 ft³

Port Displacement(Litres) - 15.01 L

Port Area - 44.0 in²

Port Area(Metric) - 283.87 cm²

Port Area Per Foot - 7.41in²

Port Area Per Litre - 47.81cm²

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[swanginfleet]

Additional pics

View attachment 26548870View attachment 26548871

 

[hispls 5,000+ posts]

New box. Bring the depth all the way back to the hatch and port on the top/side. Use adequate port area and you should even gain a little volume if you use all that space you have. Be absolutely certain you brace it well that's got some big sides on it and the wood flexing will lose a ton of output.

 

[swanginfleet]

I'm trying to plan another box but every time I make the port 15sq in per cf I can't get it to tun en low enough.

 

[swanginfleet]

Is there absolutely no way I can save this box?

 

[swanginfleet]

Could it be the program I'm using? It's off the android playstore. It's called "Box Tune Calculator". No matter how long or short I make the port it won't lower the frequency.

 

[MerkConvoy501]

use two box calculators to compare the numbers. I use re box calculator

 

[adulbrich 5,000+ posts]

use two box calculators to compare the numbers. I use re box calculator

I second this^ RE AUDIO - Box Calculator

 

[swanginfleet]

Cool, I'll try that. I tried this one Port Length Calculator, it seems more realistic. I've gotten different box programs and gotten different answers. I'll definitely try the re one.

 

[swanginfleet]

Also, do I insert the total box volume in the program or the volume after displacements.

 

[adulbrich 5,000+ posts]

Also, do I insert the total box volume in the program or the volume after displacements.

For the RE calculator, it is before displacement

 

[swanginfleet]

OK thanks. It's not looking too good, the port is gonna be kinda long (approx 30in) If I go for around 15sq in of port per ft. I would have to run the port up the back wall close to the sub. Can I do that?

 

[swanginfleet]

What's the main theory of the 14-16sq in per cf? Is it to make sure you don't have port noise?

 

[swanginfleet]

I just need an answer to the theory because if it's just to ensure no port noise I might keep it the way it is. It's actually not too bad on lows. It will handle to about 29-30 nicely. I guess I'm just used to the btl n2 in the Cadillac, that thing drops.

 

[swanginfleet]

Ok, what if I made the port 16.5" wide, 5" tall. That would make 13.7sq in per cf. I was wondering if I could make the port T (split off) off the back wall instead of going up the back wall? I know there's someone who can answer, I'm trying to get it fixed tomorrow since Tuesday and Wednesday are my days off.