Sealed enclosure, multiple connected chambers?

[briansz]

Baron, you bring up a good point. I could stop being lazy and measure the transfer function of the truck and see what F3 really needs to be. I've mostly grown up and this is a SQ system. 3-Way MB Quart QM-series components, 2x Sony XM-7547 amps at 100x4 (two channels of one amp bridged to give the sub ~ 400x1). I have a Clarion 3-way crossover that has variable boost/center freq/Q to do active high pass and an Audio Control DQL if more massaging is needed.

Sounds easier than cutting

[revboden]

Is it possible.. I'm curious how large would the back chamber volume be, how long would the tubes be and what diameter, and what would the front chamber volume be, I would like to model this. for fun

[briansz]

As it's shown, the front chamber is nominally .375 cubic feet, rear .5 cubic feet, vents are two 3" ID at 5" long.

[BP1Fanatic]

Originally Posted by briansz

I've mostly grown up and this is a SQ system.

The difference between a man and a boy is the size of their toys

[TheBaronGroog]

Check the graph below, there's an F350 in the mix-which may be close enough to your vehicle that it doesn't matter.
http://farm4.static.flickr.com/3194/...d155d5ac_o.jpg

I've read quite a lot on the topic, Patrick Bateman has a very interesting theory regarding it-seems to make sense. Basically cabin gain is pressure and standing waves, the internal dimensions of your vehicle can give you clues to where you'll get the peaks: height of cab, width of cab and length of cab. If you ever venture onto DIYMA extremerevoltion can model it for you, otherwise if you know someone with LEAP it can model it.

Does Anyone Understand Cabin Gain - DIYMA.com - Scientific Car Audio - Truth in Sound Quality

[briansz]

I've actually been on DIYMA for awhile, but folks there suggested diyaudio for my question about the multi-chambered box. Didn't realize you could calculate cabin gain from dimensions; I was just thinking of the old-fashioned way with PC-based RTA software and a measurement mic (meter sub in car, meter sub in free space, difference = cabin gain). I've also got an old Gold-Line 30 RTA, but the PC's easier to use when comparing curves. Love Patrick Bateman's threads, have killed many hours reading the horn ones, but did not realize he had explored cabin gain.

I guess if I had to, I could pick up one of the new Type R 8's or even use my old JL 10W6v1, but I got the 8W7 in original box for a great price and want to try and use it. I'll have to do some cutting and fab together a test box for experimentation. Supposed to get a big dump of snow here tonight and tomorrow so it may have to wait a few days.

[TheBaronGroog]

Yes, dimensions will do it, but if you've a sub and RTA it's probably quicker and more accurate-provided the test sub is going where you're going to fit your W8 and you mic from your head position.

Yup, Patricks threads are great-have you visited Audio Psychosis?-it's his own forum-he's the main contributer-there's some interesting stuff on there too.

What's your username on diyma?

I'm gonna pull the specs off the w8 and see how it'd model in my car-will post the graphs

[TheBaronGroog]

If you can make the enclosure volume 0.386cf you can expect a response like below. Green line is the 8W7, Purple is my Aliante. Mine is crossed over at 63Hz so as to not play through the Fb, you'd have to cross yours below 53.69Hz.

[revboden]

The ports would tune to 100.6Hz back, 116.3Hz front, as long as the XO is set below ~80Hz with a high order XO the two chambers will couple effectively.

[briansz]

Thanks everybody for the good info!

- I think I'm going to try out what Baron has suggested first; if it doesn't work out, I can always use that box as the front chamber of the two-box-and-tubes design and go from there.

- 8W7 isn't too useful above 85Hz to begin with; Clarion MCD360 crossover is 18dB/Octave slope so it might actually work with the twin-chamber design if the tiny box/cabin gain method is not satisfactory.

- I've got the same ID on DIYMA as here (original, huh?)

- Snow-Pocalypse seems to have happened (a foot and counting overnight), so I doubt I'll be cutting any MDF until at least next weekend.