audio1der

I currently have my new 2.5(net)ft^3 box tuned to 36Hz with 2, 4" aero ports.
At full tilt around 29-30Hz I get some chuffing, and was looking at what it would take to go to 6" or even 8" round port, but OH MY GOD it gets insane for length!?
http://www.carstereo.com/help/Articles.cfm?id=31
(Dukk always references this haha) It tells me to use a minimum of 9.1" diameter which works out to 47" long. Give me a break!
I can manage a 6" which isn't altogether different in length than my dual 4"s at about 19" and change, but I don't know if the velocity would be that much better managed to make the swap worth it?

Dukk

a single 6", as you found, appears to have only marginally more area than two 4" but it has way less wall, so less boundary layer, which means more free area for air flow.

It might do the trick but not sure I would make the change. Can you add a 3rd 4"?

I like that link - one of very few that will tell you how much area you should have.

audio1der

With 3x 4" ports, each would need to be 28" long; that's a no-go. Idon't have internal volume, not space around the box into the cabin to do this.
I'd like to ghetto-fab some sono tube but the port needs a 90* elbow...need to think on that. Commerically available 6" aero ports (Madisound has the only one I can find) can't accomodate a bend.

stochastic

http://creativesound.ca/details.php?model=6FP
Looks to be cheaper than Madisound and is a Canadian company. These ports can easily be cut and modded with 6"PVC from Rona or a similar store.

Dukk

You can get 6" bends but need to go to a commercial supplier. You could always pie cut pieces to make the bend - better than a hard 90.

audio1der

If required I would pie cut the 6" with my (power) mitre saw, but I would prefer to use thin-wall drain pipe & premade elbows like I did with my 4", from Plumbful warehouse.

audio1der

Still mulling this over while I wait for my recone.
A length of 6" thin wall drain PVC is $79 and would need a 6" elbow too.
Commercially available 6" aero ports come with only 12" of stright pipe (might need extra as well as an elbow)-$58 ++
A length of 6" sonotube is $8.
I need to figure out a way of making flares.

stochastic

Duct tape or fiberglass?

The flare isn't totally essential, but does significantly help. One could also take the flare from a commercial port and attach it to some sonotube.