Is a sealed box that is 20% smaller than it should be necessarily a deal breaker? Doesn't it provide some measure of protection against cone overexcursion? Will it really be taking that much performance out of the woofers? Will it be "good enough" is what I'm getting at, I guess. I am not looking for "competition" performance or anything, just a good kick drum feeling like in the first part of Robert Palmer's "Addicted to Love" I don't even need it to go really low.

I got plans for my 1999 Dodge Ram 1500 van with four captain's chairs and a rear electric reclining couch.

The place I want to put the woofer box has max dimensions of 48" wide, 10.5" high, and 7" deep. These are the absolute limits of the outside dimensions of the box. Can't make it any larger without it getting in the way. It's going to go under the front edge of the rear couch. If it is any deeper, people's legs will rest on the upper corner.

I have four 8" woofers which require 0.55 cu ft each. Two will be on each side, with the enclosure walled off in between the pairs - the amp driving these four woofers (Panasonic CY-PA2003U) will have each side driving one pair of woofers and a one 6x9 (there's one 6x9 on each side, mounted in the wall just ahead of the couch). The front part of the van will have its own amp, same model.

Problem is, when I do the math for a sealed box, I come in below the 1.1 cu ft per side that each pair of 8's will need (documentation calls for 0.55 cu ft each). I might get to 0.89 cu ft per side depending on what board thickness I use, but I was hoping to use 3/4" MDF. Would 5/8" thick MDF be feasible for four 8" woofers? I am going to brace it internally.

So, it comes down to a ported box if I want to make the available space work. This port calculator page I found seems to require a port length that would simply not be possible:

http://www.carstereo.com/help/Articles.cfm?id=31

With two 8" woofers, and a tuning freq of 40 hz, the first part gives me a port diameter of 4 inches.

Entering the 4 inch value into the Vent Length calculator at the bottom half of the page, keeping the tuning frequency at 40 hz, and the enclosure volume at 0.89 cu ft, I get a Vent Length of 20.86 inches! Bah!

Is it simply not possible (or convenient) to vent a box that small with two 8" woofers?

I'm hoping to get away with not porting the box.

Thanks very much for any insight!

p.s. - Gear I have ready to install in the van:

Head unit - JVC KD-DV5300 Mobile DVD Player
(2) Bravo CNIC OVR-104 Overhead LCD Monitor (1 front, 1 rear)
(2) Panasonic CY-PA2003U 2-Channel Amps
(2) Clarion ProAudio SRH292HX Tweeters (front, going to put bass-blocking caps on the Pioneer 3 1/2"s already in the dash, and hope for the best)
(2 pairs) Panasonic CJ-A6933 3-Way Speaker (1 pair front doors, 1 pair rear walls)
(4) Boss Chaos CH8 8" Subwoofers (cheap, but effective)

 

Hmmmm.....

Yes the box will work, a pound of fill in each side will add enough effective space to work.

You need to separate the 6X9s from the subs. I would suggest you use 1 of your amps for the subs, running in 2ohm stereo.

If front to rear fading is important, another amp is needed for the rear 6X9s.

You can run the front 6X9s and the 3.5s off the other amp with caps to filter out lows from the smaller speakers. If that isn't enough treble, the deck power (capped again) should be enough for those extra tweeters.

If you really want to power everything on amp power, which I like to do, it could be done several different ways.

For example, if you get another one of those same amps, you can can use 1 for the subs, 1 for the 6X9s (front and rear) and the third for the 3.5s and the tweeters. By putting the front outputs on the small speakers, the rears on the amp for the 2 pairs of 6X9s and the sub outs for the sub amp you should be able to adjust the sound levels to your liking. This setup also gets the most possible out of your amps, since they are all running in 2ohm stereo with the right frequency ranges for each type of speaker.

I'm sure others will have alternate ideas.....the van has a lot of possibilities and sounds like it should be a blast when it's all done.....

HTH

 

It's good to know that I won't have to port it if I use the fill. Some good ideas on the amp distribution, I will probably do that.

Thanks!

 

YW!

I have fond memories of a couple of vans from back in the day.....with all that space, wild installs are much easier, but SPL levels will suffer....

HTH