Bandpass box for 2 SA 12s

[ncochran]

Anyone here able to help a little. I am trying to hit 25-60hz as cleanly as possible. Mainly for demo purposes. I am not looking for anyone to design it for me, I can work out dimensions and all that. I just need advice on volume, tuning, and port area.

Due to space limitations I was thinking somewhere around .75 each sub sealed, and 1.5 each ported. As for tuning and port area I am clueless though. Thanks for any input.

[STEALTH808]

lol so basically you need someone to design it for you but dont wanna pay right?

[ncochran]

Wow lol... re-read please. I actually have no problem paying if someone was to design one with dimensions/cut sheet etc... But if you actually read, that is not what I am looking for. I was hoping that someone here had put a couple of 12s in a 4th, and wouldn't mind sharing what worked for them so I would have a starting point. I very specifically said that I don't need a design, I am looking for ADVICE on it.

Way to up your post count though.. Thanks for the bump jerk.

[STEALTH808]

yeah i read that you need help on volume, port area and tuning but dont need help designing a box.... thats like saying i need the answer to problem 3 to my math test but i dont wanna cheat.

[STEALTH808]

ok so you want a flat response? you will wanna probably wanna stick with 2:1 ratio.

you want a flat response and hit lows? you might wanna go a little bigger on the sealed side. maybe around 1 cuft net per cube.

tuning? most people tune around 44-48 hz. so maybe 45hz?

port area? around half your cone area is a starting point.

[ncochran]

Thanks, that is actually the sort of info I am looking for. As I said above, since this IS the Sundown forum, hopefully someone here has experience with these subs and can share their actual experience as well.

The challenge will be fitting what I want in a pretty limited space (06 scion xb, without removing rear seats). And people flat out ask for designs here all the time. But again, I am not. The design and dimensions will be my own. The specs will hopefully come from an overview of others experience with the SA series subs. Make sense?

Edited June 2, 2013 by ncochran

[CleanSierra]

Beeemdub has an old thread asking about a 4th with the same subs. I'd say shoot for 2:1 or 2.5:1 with strong 80-100" of port.

When I used the search feature at work tonight, I found that old thread.

I'll edit this post and paste the linkey

***Edit- Here you go:

http://www.stevemeadedesigns.com/board/topic/142206-how-much-port-should-this-4th-order-have/

Edited June 2, 2013 by CleanSierra

[CleanSierra]

That is obviously a rough idea where that link takes you. You make PM HIM though to see if he ever built it or if it worked out.

OP you have good woodworking skills, so I think you'll be able to build it relatively easy. If it were me, I'd tune it around 48ish to get a good range of response in THAT car. You may be able to go a little lower, but you may sacrifice the higher end and in turn, need one hell of a mid stage to compensate.

[Raptorman]

I've heard from a lot of reputable guys with ground pounding 4ths that ratios are not something to worry about, but it's the individual volumes for each section that you need to worry about, and that tuning doesn't play as much of a factor where as port area plays more of a factor as to how well/flat it sounds.

I hear 18-19 square inches of port per cube in the ported section is a good place to start.

I'd say 1 cube per sub after displacements for sealed, and 1.75 per sub after displacements for ported.

[CleanSierra]

P.S. I know that the cargo area in that car is hella small so good luck. I'd estimate that at LEAST 7 cubes will be needed before all displacements. 2 sealed, 4 ported, plus driver and port displacements. Probably close to 8 cubes for a 2:1