SQLAlpine69

Hey im building a box for my truck im planning it to be 30 x 11 x 12 and i just need some help for the vent im not to sure how to go about this i would like to have sub on the right side and port on the left i could draw a diagram if needed im not sure on how to build the vent

Denonite

iTrader: (1)

Use a slot port given how thin the box is. Depending on what frequency you want it tuned to, the port length and width can be adjusted...the height will be the inside height dimensions(i.e. if your box height is 12" and you use 3/4 mdf, then the port's height will be 12-2(3/4)=10.5"). Using a program like winisd, you can calculate exactly what width and length you need to get the tuning you want. Nice thing about slot ports is you can use the existing box walls for the port's outside walls.

SQLAlpine69

thanks alot so far you wer alota help but i have one question as for winisd when it gives me vent length i get 24inches so can i do like an L shaped port to compensate because it wouldnt fit in the box other wise o and what is vent mach? thanks again for help

Denonite

iTrader: (1)

certainly...L shaped is what everyone does! Vent mach (air speed in the vent) should be below 16m/s if I recall. That prevents vent noise (huffing) at high output levels. If you enter max power (500 watts rms) in the specs, and look at the vent speed, you'll see at what frequency the air speed is highest. There are a few simple ways to get it low enough to be undetectable; larger port area (H x W), though you usually have to make the port longer, and adjusting the tuning frequency, though this can get tricky and screw up the tuning. Play with both until you have an acceptable compromise. Welcome to enclosure design!!

jalat

iTrader: (6)

30"w
11"d
12"h

that gives you an internal cubic footage of 1.65
your gong to need at least 1.75 cubic feet after all displacements for that woofer to sound good.
what are your maximum dimensions you have to work with?

Denonite

iTrader: (1)

^^that's not true....it needs 1.7 cubes gross, 1.3 net(after port and speaker displacement) according to Alpine's manual.....therefore, 0.05 cubes isn't going to cause any problems. Additionally, he can add 1.5 pounds of polyfill for insurance (don't need it really, but you can experiment).

Denonite

iTrader: (1)

^^by the way those subs sound very good in the Alpine boxes...I had 2 type r's in a 3.4 cube ported to their specs...very good overall sound. Can it get louder in another box...probably!...does it sound better...maybe?? This set up sounds damn good though, and gets plenty loud with 1 kw of power. You can't go wrong with it, and if you have the time, patience, or inclination...you can experiment with other designs.

SQLAlpine69

thanks everyone just finished box and sounds twice as good for sq than the store bought basswork one that i got with it and it hits harder and louder than any other 12 inch ive herd

jalat

iTrader: (6)

polyfill is garbage in ported enclosures.

and i would NEVER have a 12" woofer in a 1.3 cube enclosure, unless i wanted it to play 58hz test tones all day with triple its RMS thrown at it

Denonite

iTrader: (1)

whatever...anyway, original poster you have some more info. You need to know what your parameters are, and build accordingly. Not everyone has 3 cubes to dedicate to a sub system, unfortunately compromises are necessary in daily drivers. This being the SQ section, usually earth shattering bass isn't the be all..that's the other section.