Custom Enclosure: Port question

[CdnCory]

I posted the plans a while back, but you can check out the design here. My question is if it would be worth the effort to make the corner of my ports round or if it would be just fine to angle it?

(I also posted on sounddomain, but want some of your opinions too)

Also, I'm looking for any last minute critique on the overall design.
Cory

 

[Interstate]

Well, since air is a fluid, I could only presume that a rounded port would work marginally better being that there would be less turbulent air coming out of the port: allowing more air to flow and allowing the air to flow smoothly. That's just my airmchair scientist guess though.

 

[danq]

The rounded port is better. how much, I don't know.
This is all because of some thing called prandl-meyer flow. Picture the sound wave as a thin wall. This thin wall will travel around corners. The part of the wall that is closest to the corner will adhere to the corner. As you go around the corner with this thin wall the outside edge(the edge furthest from the corner) gets faster. When this edge gets fast enough it breaks the speed of sound. This is what we all know as port noise. With a less sharp corner the outside edge of the wall will not move as fast. This is how you avoid port noise. Your two options above both look like they will work fine. But, if it only takes a little more time then why not.

dan

 

[CdnCory]

Ya, i kinda figured that the rounded corner would be better, so next Q is... how do I make that rounded corner? I was thinking, maybe use a bunch of bondo then smooth it all out?

Cory

 

[lonefx4]

i dont even have that corner thing in my box and it hits nicely. just the straight 90* of the corner of the box.

 

[Interstate]

I guess you could use bondo, but wouldn't that weigh a lot and crack over time? I would cut a wedge of wood, then use a belt sander (or jig/band saw, or whatever you think would work best) to take the majority of material out, then hand sand to get the exact shape I wanted. Granted it'd take a lot longer than bondo, but the end result would be better, IMO. Plus I don't really know how the bondo would affect the acoustics of the subs either.

 

[davesexplorer]

PVC tubing works excellent for smooth curves

 

[CdnCory]

I was also thinking of PVC, but each box will be for two gTi's, and those will be moving alot of air. I want somehting that will give a really solid curve in the corner.

Cory

 

[davesexplorer]

What's pvc normally like 1/8" thick - those GTi's shouldn't warp or comprimise the PVC. I think there is 1/4" thick pvc too if you're worried.

 

[Interstate]

PVC isn't very stiff though: it'd vibrate like mad and would again compromise sound quality.

 

[Wagonized]

rounded is better but IMO the gains achieved really arent worth the work that has to go into it.

Rounding off the edges of the port where it exits the box with a router is worthwhile to prevent port noise though

 

[mexi]

its not worth the effort you wont be able to tell a diff.