dsliner

I'm building a ported box that will fit in the back of my Jeep Wrangler TJ. Don't have much space at all. I have 1 10W6v2D4 that will be ran on a REN850s amp. I'm coming up with a rough estimate of about 1.5 cubes after displacements. Looking to tune to 32 hz using a 7"x3" port ran 29.5" long with a single bend. The box will be a downfire box with a wedge structure.

questions:
Has anyone here ran a 10w6 in a ported box? what airspace did you use? I've seen some in 2 cubes that sounded great. don't know what they tuned to though.

Port direction... with the speaker firing down the box is pretty tight in there so the only directions would be either up or down. up will be out in the open but that would put the port running across the top. Thoughts on this?

Sonic

iTrader: (1)

for best results >> sub firing down, port firing forward (if possible).

1.5 cubes tuned to 32
port = 7" x 2.75"
Port length = 30"

dsliner

can't fire the port out the front. box is up against the back of the seat. I can run the port across the top going out of the side.

Sonic

iTrader: (1)

ok, that would be your best option.

Dukk

In that car, because the top comes off, I suggest both the woofer and the vent point at the floor, spaced up about 2".

I'd tune it closer to 40hz too if that doesn't mess with the alignment too much.

dsliner

Why run at 40hz? I thought 32 would be ideal. From what i understand, a 10" speaker already sounds loud at higher bass tones. I'm wanting to get those realy low notes to come out. Thoughts??

Also, on the down fire port... I'm looking at a minimum port area of about 20 sq in. which tuned to 32hz in a 1.5 cube box puts the length at about 30" long. the box will only be about 15" tall so I'd have to start at the top and 90 it to fire down where as if I run the port across the top of the box which will be roughly 33" long, it can be straight. Thoughts???

Sonic

iTrader: (1)

It's a trade off, tuning that low you will loose output, and do remember it's an open top with a 10'' sub, hence, far less than inside a cab.
If tuning in the upper 30's to 40's then as dukk recommend both sub and port firing down would be good, and there is nothing wrong with having the port bend 90 drgrees to fire down.

The orientation I suggested above is based on people who have experimented on their open top vehicle.

It all depends on what you want, some experiments would definitely yield whats best in your situation, i.e. tuning, sub and port firing orientation.

Dukk

So I decided to run this through WinISD. I modelled three enclosures:
1. JL's recommended 0.75cuft tuned to 38hz
2. Your 1.5cuft tuned to 32hz
3. 1.5cuft tuned to 38hz

The results were pretty close really. F3 was 34 / 27 / 31hz so relatively close. #2 was 4db louder at 30hz than #3 and 6.7db louder than #1 (remember these are relative only) while #3 was loudest, peaking 2.5db above #2 at 43hz.

Not huge differences but #2 would sound like it has a little bit more grunt but the tradeoff is that box #2 also exceeds Xmaxx by almost 20% at 42hz which means you have to keep the volume control in check when the heavy stuff comes on.

Biggest difference is box #2 needs 31" of vent, too long IMO, while box #3 needs 21", still on the long side but not too long.

I like to point the woofer and vent down in open top vehicles to keep the loading more consistent whether there is a hard top or open air.

mommjomma

i wouldnt suggest having a 3"x7"xwhatever legnth port firing at anything, like a floor, that is 2" away regardless of roof, the potential backpressure back into the port, escpecially with a woofer with the excurision capabilities and high mach factor abilities as the JLw6 woofers, is undesirable. Would it be possible to have the vent made narrower and wider to perhaps vent under the rear seat?...This would be much more desirable than being pointed into the floor only 2" away from the vent opening

Dukk

That may be your opinion, but the generally accepted minimum is half the smallest dimension, with the goal a full smallest dimension or more. This is called "boundary loading" and is quite common.

So for a 4x5 rectangular vent, or a 4" round port, 2" is fine. Move that to a 2x10 rectangular vent, which is very likely in an enclosure like this if the vent opening is on the baffle with a 10" driver, and 2" is ideal.

Good use of "high mach factor abilities" though. Going to have to keep that one handy..