Ghetto Port Cannon coming out of home theater enclosure or what?

[skylineTT 10+ year member]

Designing a new box for my logitech z-560 (tang band 8) system that is restrained deminsion-wise due to lack of space on computer desk. im building with 1/4" mdf and the internal volume will be 1.53733 cubic feet before sub and plate amp displacement. the stock port is about 3.5 in diameter and only long enough for about 45hz tuning but im looking to do about 28hz so 12volt's box calc says i need about 14 inches of port to get that low and thats only with a 3" port. that will take up a good chunk of box volume if the port is internal so i was thinking about doing a ghetto cannon port that shoots out of the side behind my laptop in order to maintain tuning and volume but i dont like the idea. is there a better way of going about this problem?

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[brandon_s0854 10+ year member]

There's really no way around it. In order to decrease tuning frequency, you have to increase cabinet volume, decrease port area, or increase port length. However, there might be someone on here with a creative suggestion. Sorry I couldn't be more help.

 

[bubbagumper6 5,000+ posts]

Make the box bigger?

 

[Linkz 10+ year member]

Could you do a PR box? A 12" Pr should do it for you.

 

[brandon_s0854 10+ year member]

Yes, if you make the cabinet bigger, the same size port will yield a lower tune. Honestly, it sounds like you need a smaller port. I don't see any reason why your tang band 8 would need any more than a 2" port. A passive radiator would work too, as mentioned by linkz.

 

[skylineTT 10+ year member]

ahh pr is a good idea, i measured the stock 3.5" port to be about 13" and flared so i might just say "screw it" and build the box an inch wider and an inch taller. this will yield enough volume to swing 28ish hz with the stock port. I am also thinking about throwing an FI X 10 into the equation because of its low power handling, low Fs, and high excursion. seems like a great sub for this power and tuning (200w) and i wouldnt have to change the box really. would a PR box get louder? I have zero experience with them.

 

[hispls 5,000+ posts]

Designing a new box for my logitech z-560 (tang band 8) system that is restrained deminsion-wise due to lack of space on computer desk. im building with 1/4" mdf and the internal volume will be 1.53733 cubic feet before sub and plate amp displacement. the stock port is about 3.5 in diameter and only long enough for about 45hz tuning but im looking to do about 28hz so 12volt's box calc says i need about 14 inches of port to get that low and thats only with a 3" port. that will take up a good chunk of box volume if the port is internal so i was thinking about doing a ghetto cannon port that shoots out of the side behind my laptop in order to maintain tuning and volume but i dont like the idea. is there a better way of going about this problem?

Go to the plumbing store and buy a bunch of 90 degree turns for the port, or calclulate for slot port (will take up internal volume still). Or pick up/build a passive radiator FTW. PR will do about the same thing as a port, just rolls off quicker below tuning and has no port noise.

 

[skylineTT 10+ year member]

ahh so it isnt as pitch friendly as a normal port? i might build this aero'd box and if i dont like it, pick up a PR on parts express and go that route. ive always been interested in the way they work. I'm assume that you can tune the box based on the size of the PR or something?