Me and my uncle starting building a tempest sonotube and need some help on ports (1 Viewer)

[Scott Parker]

Alright, we went out and bought a 12' piece of 24" sonotube yesterday. And I just ordered my Tempest a couple minutes ago. We figured we'd cut it into 3 pieces makes 3 4' subs. Were wondering what to do with the ports. Dan's design suggested we put 2 4" 17" ports on the bottom, but I figured wouldn't it be easier to just put 'em on the top. That way we can save room for some nice beefy legs. We were thinking 4" PVC caps. Does it matter where you put 'em. And if I wasn't gonna do 2 4" flared, could I just put a 6" port on the top that wasn't flared, pvc or something. We're going with the MDF for the endcaps, and 2 glued together for the bottom, just to let ya know. Okay couple more questions, what's the difference in a class AB amp and a class D amp, parts express has both. Is the #300-794 about the same as the AVA250? I guess I would need them to defeat the bass boost at 30hz for me right, and is the rumble filter okay or can I get that taken off too. Okay im done, thanx

 

[Dave Poehlman]

could I just put a 6" port on the top that wasn't flared, pvc or something.

If you mean a single 6" diameter port.. yes you could put one in at about 16.5" in length rather than the 2 ports.

 

[Jack Gilvey]

Or a hamster.

 

[Patrick Sun]

Jack, ermm...you know something we don't know?

 

[Brian Bunge]

Jack,
PVC tube and hampsters are Richard Gere's domain, aren't they?
Brian

 

[Scott Parker]

Aight, that's cool I didn't really think the placement mattered either, I just wanted to know for sure. So what do you guys think about the partsexpress amp, its $50 bucks cheaper for what looks like the same thing aside from the bass boost. They still haven't emailed me back about whether or not they could defeat the bass boost or not.

 

[Robert_J]

IIRC, the PE 300-794 has the bass boost defeated. If not, PE will send you the resistors to do it. They are also very helpful at the PE Tech Talk Board.

-Robert

 

[Scott Parker]

Alright, one more thing, poly batting. I've been looking around for some options and I found this one store with 2 different densities. I think they're both around 1 and a quarter, should I go for the more dense one. Or should I just pick up some polyfill at walmart and stuff it in there? And if I went the poly batting way, would 1 layer be enough, cause I read one guy used 3 layers. How do you glue all those together?

 

[Dave Poehlman]

Alright, one more thing, poly batting.

Stuffing a ported box has a different purpose than stuffing in a sealed enclosure. For a ported box, the goal is to actually "damp" any resonant frequencies inside the enclosure. Since we're talking about a ported subwoofer here, the wavelengths you're dealing with will probably be larger than your 4' sub. So, it's not likely you'll have a problem with resonant freqs.

The more likely scenario is that your enclosure will resonate or vibrate, so your goal is to make the box/tube as acoustically "dead" as possible. So, if you are going to use poly fill, use the heavier. I've seen some designs that use that spray-on sound proofing stuff used on the inside of car panels. You can find this at auto parts stores... but I hear it's smelly stuff.