Port Hole For Subwoofer Box

[ANGEGALVAN1]

Hello im planning on hooking a Skar DDX 10 inch with about 1.7 to 1.8 cubic subwoofer box. I plan on making a box underneath the rear seats on a f150 but im going to lift the seat a couple of inches. My question is ive never understanded how big or long port holes should be for a box. I've used PVC pipe on 3 boxes already and they've sounded good. So would a 5 inch or 4 inch diameter pvc pipe be good for the box ? And im not sure about the lenght of it.

Click to read more...

 

[Popwarhomie 5,000+ posts]

Just randomly sticking a PVC pipe in a box is a horrible idea. Need the proper port area and tuning which is dependent on the diameter and length of the port.

 

[n2audio 5,000+ posts]

based on Skar's recommendations:
With 1.75 cf net enclosure volume and 22" sq. in. of port area you'd need a 5" tube about 16" long. That would give you a tuning freq of 39. Seems a little high, but would probably maximize SPL at ~40hz.

And port/sub displacement would require your box to be about 2.0 cf gross -- pretty big for under a seat.

 

[ANGEGALVAN1]

Just randomly sticking a PVC pipe in a box is a horrible idea. Need the proper port area and tuning which is dependent on the diameter and length of the port.

Sorry got to excited with the build, so i put in a 4 inch diameter and about 9 inch long port and she loves the 35hz, I feel like the port is too small so might bump it up to 5 inch

 

[ANGEGALVAN1]

based on Skar's recommendations:
With 1.75 cf net enclosure volume and 22" sq. in. of port area you'd need a 5" tube about 16" long. That would give you a tuning freq of 39. Seems a little high, but would probably maximize SPL at ~40hz.

And port/sub displacement would require your box to be about 2.0 cf gross -- pretty big for under a seat.

So my box is currently like at 1.9 or 2. I put in a 4 inch port that is about 9 inches long. She sounds really nice for a 10 but i feel like she has a higher potential. I want to stick in a 5 inch port or a 6 inch port. I just want it to tune it at 35hz or around there. I have it hooked up to a Hifonics GEX 1300 and

 

[n2audio 5,000+ posts]

You're tuned 39 ish. If you change to 5" dia you'd need to increase the length to 14-14.5" to retain a similar Fb.

 

[ANGEGALVAN1]

You're tuned 39 ish. If you change to 5" dia you'd need to increase the length to 14-14.5" to retain a similar Fb.

Okay thanks ! it hits good at 35hz