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goodguy8705
02-24-2009, 03:27 AM
I decided to go with a vented enclosure but I plan on using a design that is not widely used and have had a hard time finding a design for one, nor do I have the skill and know how to design one myself.

I come to you for help.

First, without actual specs, is there anything wrong with a design like this:

http://img25.imageshack.us/img25/5646/88561649.png

OR would this be a better design:

http://img513.imageshack.us/img513/6629/60833969.png

The reason I want to use that shape is, the vent would be pointing towards the open ports in my rear deck where the 6x9's used to be, and due to the long narrow design, put the sub close to the back of the trunk while leaving the other half of the trunk useful.

Does that make sense?

I plan on getting dimensions for my trunk tomorrow to better gauge how long, tall and wide the box can be to work well.

I plan to make it with 2.5 cu ft volume after sub and port displacement and want to tune it to roughly 24 hz. The box is for a single 12" Fi Q that will be getting around 1000-1200w.

If I can provide some measurements, can anyone help me with the actual design and dimensions of the box to fit my specs?

SSS 18734
02-24-2009, 04:06 AM
There's no reason that this wouldn't work, but it would be much more space efficient if you made the box fill the width of your trunk and pushed it all the way towards your seats. You could then either seal it off from the trunk completely and face the subs forward and the ports through deck. If you don't want to do that, either face the subs and ports up or towards the back.

I might be able to help you with a design over the next week if you post your preferences and maximum dimensions.

goodguy8705
02-24-2009, 08:32 AM
The reason I was doing all of this was to maximize output by putting the sub as close to the back as possible. Sealing a box is out of the question as I don't have the tools or money.

I also planned to leave about 6-8 inches of clearance on top of the box to mount 2 small amps. It just seemed like a cleaner option to keep everything on one side of the trunk.

I planned on cutting the floor panel and putting a hinge on it to allow access to the spare if I need it... if it's possible. Otherwise, I'll probably just take it out and buy some Fix-a-Flat or something.

kush-divinity
02-24-2009, 11:10 AM
Is this going in an old Cadillac? I had the same issue with an 87 Fleetwood.

The idea is sound, and I tried something very similar, but was greatly displeased.

I built a new enclosure, subs forward, port forward, and slid it all the way to the front. I had plenty of room behind the box for my tools and extra clothes.

You can do as I did, and run a 2x2 strip around the sides and top of the box. After it is in place, you can screw MDF panels cut to fit your trunk to seal it. I screwed some of mine to the metal in the trunk, then hit it with Great Stuff to seal it. That simple 3 hour project eliminated 90% of my trunk rattle, and added a nice bit of pressure in-car.

goodguy8705
02-24-2009, 11:24 AM
I don't want to seal off the car as I would like to be able to carry stuff and access the trunk from the interior.

kush-divinity
02-24-2009, 11:33 AM
Well, in that case, I'd still go subs/port to front, and scoot the box as close to the rear seat as possible. I took out my rear 6x9's as well. Used the old holes as cabin ports. You can still fit alot of **** behind your box. No real need to seal, unless you HAVE to get 1 more dB out of it.

goodguy8705
02-24-2009, 12:08 PM
I thought that the best quality and SPL occured when the sub is as close to the back of the car as possible, due to the front and rear produced waves being as close together as possible.

IDSkoT
02-24-2009, 12:09 PM
OP: Check out JBLCamry's latest build. It's basically the same thing, except he uses a sick *** 10" PVC port.

IDSkoT
02-24-2009, 12:28 PM
I thought that the best quality and SPL occured when the sub is as close to the back of the car as possible, due to the front and rear produced waves being as close together as possible.

Not always. The idea is that it refracts and has a "Doppler" effect, so it's supposed to increase the sound by positive cancellation and what not. However, if you do subs forward / port forward and seal off the trunk, it has a lot less room to pressurize, so in most cases, the dB levels will increase (and most of the time becoming audibly louder.)

goodguy8705
02-24-2009, 12:47 PM
There will be no sealing.

DonH
02-24-2009, 01:43 PM
bro best thing to do is experiment!!!!

SSS 18734
02-24-2009, 01:43 PM
In your case, I would just build a regular rectangular box with the port and sub on the same plane; that way, you can move it around into the position that sounds best.

goodguy8705
02-24-2009, 04:56 PM
I would do that if I had extra money or planned on moving this thing around after it's installed, but truth be told, I'm getting one box, it's going in and it's not moving until something breaks or it's stolen.

I could put the port right next to the sub, but I would still go for an enclosure that's the depth or close to the depth of my trunk as to leave one side completely empty.

I'm measuring my trunk later today.

kush-divinity
02-24-2009, 05:03 PM
Sounds like you have your mind made up. Go for it then.

I have only experienced one box made like that. It was loud, but very peaky around tuning freq. Might have just been the sub tho........

I think in the end, you will change your mind, after listening to people laugh at your massive trunk/plate/taillight/bumper rattles.

Johnny Law.Lulz
02-24-2009, 05:09 PM
yeah, you seem pretty closed minded on this but it might sound good good luck

goodguy8705
02-24-2009, 06:11 PM
I was going to put 3 or 4 layers of eDead V3 in the trunk. Would it be worth it?

goodguy8705
02-25-2009, 02:07 AM
Added an alternative option that is probably a better choice.

SSS 18734
02-25-2009, 02:15 AM
Your second design is more tried-and-true. Most people have good results with a setup like that.

Let me know what your max dimensions and sub t/s parameters are, and I'll help you design an enclosure for your build. Posting a pic of your trunk will help too. My only stipulation is that you post a build log!

Also, I'd personally tune a bit higher. Your box really should be significantly larger for a 24hz tune. Keep in mind cabin gain will help you out on the lows. I wouldn't tune lower than 28-29hz, and increase the box size a bit.

goodguy8705
02-25-2009, 05:23 AM
I picked those specs because it was the best option for group delay as well as an incredibly flat response curve.

This is an SQ build more than anything. I figured, tune to 24hz, set the sub-sonic filter to 18-20hz, and the lpf to 80 hz and that should be good at hitting the entire spectrum with low group delay above 45hz where it's most notable. There is no peaking in the bass response which was something I was trying to accomplish.

kush-divinity
02-25-2009, 10:06 AM
I picked those specs because it was the best option for group delay as well as an incredibly flat response curve.

This is an SQ build more than anything. I figured, tune to 24hz, set the sub-sonic filter to 18-20hz, and the lpf to 80 hz and that should be good at hitting the entire spectrum with low group delay above 45hz where it's most notable. There is no peaking in the bass response which was something I was trying to accomplish.

All that is nice, but it is generated on a computer.

Which is fine for an arm-chair commando.

In-car, you will see a different story. Everything in your car will change that response curve that you mapped out. Windows down or up, seats laying back or straight up, your headliner/lack of/deadend liner.

Ima go with SSS, make the box a fudge larger than specs call for, and tune to 30 with a decent sized port area. Keep it fired to front as well. You won't be disappointed.

goodguy8705
02-25-2009, 10:43 AM
Unless you can explain how those things change the response curve, I don't plan on tuning above 28hz.

goodguy8705
03-04-2009, 01:33 AM
Alright, I did some measurements.

I want to constrain the depth to 30" and the height to 15" while the width can be adjusted freely.

I'm looking for 2.5 cu ft of volume after the .16 cu ft of displacement of the woofer and a tuning of between 24 and 25 hz.

Any help would be GREATLY appreciated.

SSS 18734
03-04-2009, 01:57 AM
Alright, I did some measurements.

I want to constrain the depth to 30" and the height to 15" while the width can be adjusted freely.

I'm looking for 2.5 cu ft of volume after the .16 cu ft of displacement of the woofer and a tuning of between 24 and 25 hz.

Any help would be GREATLY appreciated.

If you can wait until the weekend/beginning of next week, I might have some free time to design you an enclosure built to your dimensions and specs.

However, I personally still wouldn't build it to those specs. If you want a tuning of 24 hz I would recommend adding some volume; otherwise you're going to have a ridiculously long port. If you want to keep the 2.5 cubic feet, tune to the high twenties. (I would choose the latter)

goodguy8705
03-04-2009, 04:34 AM
When I fiddled around with RE Audio's enclosure calculator, I got port lengths between 35 and 45 inches which worked okay because the box was so long, it only needed one bend. I'll post up some of the specs I got from their site tomorrow when I have time.

I'm not in a rush at the moment, but I will be wanting to get this thing built in the next 2-3 weeks.

goodguy8705
03-10-2009, 06:58 AM
Any help?