98_Z24

iTrader: (3)

Hey guys,

Finally getting around to building a new box for my mmats. This time around I'm incorperating Plexiglass into the back wall so you can see the sub. However, the traditional slot port design doesn't allow me to do this, as it parallels the back wall. So, I'm thinking of a dual slot port design. it's definatly been done before, but I don't know if it's as good as a single slot port, of if there are any downsides to doing it this way. The concept is simple, if my port has to be 3.5" wide by 14.75" tall, and the required length needed for tuning is 30", then I'd just make a 3.5" x 14.75" port 15" deep on each side of the box. However, if the box is only 19" deep, is that going to hinder airflow or anything? What do you guys think? Here's a picture just to show what I'm roughly thinking of:

benny77

If you double the port area, you'll need to double the length (not halve) as well to keep the same tuning.

veeman

iTrader: (3)

no...your port area has doubled as mentioned above...ergo your port length will be mucho longer. I'll give you an example from winisd to illustrate what happens; 3cube box tuned to 30hz using a single 12.5x2.0x20" port...if i put two 12.5x2.0x10" ports in the same box the tuning is now 56hz. inorder to maintain the 30hz tune with two 12.5x2.0 ports, they would have to be 45.5" long each!!! Yeah, ports are a bitch!

Dukk

Either put the woofer on one side and the slot vent on the other side or, instead of running the vent along the back wall, make it into a U shape.

98_Z24

iTrader: (3)

Thanks for the quick and informative replies, I appreciate it!

Now, I may be wrong in my thinking, but here's an idea. I need to have 1 3.5" x 14.75" port 30" in length to acheive 33Hz in a box 16" Tall x 19.5" Deep by 36" Wide using 5/8 mdf (So most online calculators tell me anyways) So, what if I made 2 1.75" x 14.75" ports which were 30" in length each? By my thinking, it'll keep port area the same. And, since it's a fairly wide box, it wouldn't block the back, it'd keep the middle part open. I'd just go back ~17-18" on each side, and go the remainder (12" or so) along the back, which leaves around 8" open, enough to see the sub and show off the lighting. Hell, with the ports wrapping around it like that, it could make for even better lighting effect.

Opinions?

veeman

iTrader: (3)

yeah that will work, just a couple of things I noticed...5/8" mdf is a little thin for such a big box...use at least 3/4" mdf and a few braces, and the port tuning I get with that size box (5.4 cubes internal) with that port is closer to 27hz, not 33hz. Double check.