2 15" P3's ported in back of Tahoe

[Towlieee]

Building a box for a friend in a Tahoe, 2 rockford P3 15" subs on aprox 600-800w rms each.

Rockford recommends only 2.66cf3 at 32hz, I have plenty of space to work with, was going to go sub up/port back. Either having the port fire at the bottom of the box, or a slot port between the subs, but I'm not sure how good that would work in a sub up/port back design.

Was thinking of going 3-3.5 cf3 per sub, tuned to 32hz, with around 15^2 of port area per cube, so a total box size of maybe 7cf3, 32hz, with a 5"x20" port if I have it exit towards the bottom of the box, or around 16.5x6" or so if I was to use the port as a divider between the subs....

Does 3.5 per driver at 32hz with 15sq inches of port per driver sound good? And should I have the port run along the bottom of the box, or have it run vertical from top to bottom?

[ShadeTreeMechanic]

The port area sounds small to me. I am not familiar with that sub but i would double the area.

[Towlieee]

The port area sounds small to me. I am not familiar with that sub but i would double the area.

Aye my bad, I meant 15sq inches per cube, so around 100 sq inches total

edit: Made up some plans, might change them, gonna see what my friend thinks of the design, and if anyone thinks that is too much port area..... 6.84^3 after port/sub displacement with a 125^2 of port area tuned to 34hz using a 25x5" port.

I might add a brace in the center of the box (almost as a divider between the subs, but not actually dividing them, bringing my box size down a hair, but a negligible difference.

Just another budget build, coupled used p3 15's, and a couple used cheap as can be tiny kenwood amps, they claim 1kw rms a piece, but I'll just be happy if they can do 600+ lol...

[ShadeTreeMechanic]

When it comes to ports, bigger will be louder. Go with the most port area you can with it in the space that you have. 100 total should be fine for the power you are running.

[Wasteland_Audio]

This should do good.

[Towlieee]

Sketchup huh? I was wondering what all these new fangled programs people were using now days to mock up boxes! I gotta get that and try it out! It's been a long time since I been in the car audio world, the last 2 boxes (counting this one, makes my 3rd) that i've done recently have all been how I did it since I was a teenager, reading recommended specs online, tweaking them to what I "think" will sound better, plotting in win isd, then sitting down with a calculator a pen and paper! I actually just recently started using Torres lol, but I still prefer to sit down and calculate in my head all the board cuts though lol

This is what I came up with the other day, I think I might run with it. Going to have the port out the center bottom firing back, subs up either towards the middle-ish of the box or towards the back. I will likely slightly tweak the design, put 45's in my port bend, add a piece of mdf dividing the subs up ass a brace for the top, and also going to go around 1 - 1.25" wider on the box, to account for the brace and so I can have the sides of the box sunk in like 1/4-3/8" or so
So far what I've mocked up and drew plans out for, I'll be looking at around 6.8-6.95 cubes right around 34hz with 125^2 of port


I got a lot of catching up to do, but I have the car audio fever again... So far I've done good on these super budget builds with minimal tools lol

[ShadeTreeMechanic]

I still do all my stuff with pencil and paper. We didn't have the internet when I started. Now I use an online program to verify things. I think pencil and paper is part of the fun. Now I feel old. Lol

[Towlieee]

Thanks for showing me the power of sketchup! I tried to use it a month ago when I built the 15" box, but got mad and gave up.....
Since then I took the time to dabble in it, and learn it. I have much more to learn, but I love the software! From now on every box I build will have 3d blue prints!

I don't have any new boxes lined up to build, so to learn the software, I decided to use sketchup for the 2 most recent boxes I built. The first one was the dual 15" box I built that this thread was made for, the oter one is for the 4 12" box I built like 2 months ago. It took me FOREVER to build the basic 15" box in sketchup as I was learning, the 12" box went way quicker even though it was much more complicated.

Don't judge me too much on my box building skills, or sketchup skills lol... Next box I build will be much better with more rounded ports etc... The 4x12" box is still a work in progress, going to paint it the color of the interior of the SUV, for now running the 15" box.

4x12" P3 box, each sub is in 2.5 cubes @ roughly 35hz, chambered due to budget build, 3 different amps LOL, and one sub is d2 rest are d4.... Using amps and wire that was laying around, the subs were bought used cheap on craigslist , spent much more on the box supplies and 2nd battery, they are seeing around 2 - 2.2kw total rms

2x 15" P3's in 7 cubes @ roughly 34hz, on a soundstream t1.6000dl. Not really impressed with the amp, another craigslist find. Thought it would do near its 3,000w rms rating (hell even 2kw-2.5kw would have been okay), but it "seems" like it only puts out around 1kw-1.5kw at most... I have yet to clamp it, need to buy a clamp meter (got a oscilloscope), would like to see what it actually puts out, but I can push it until its clipping and it still wont bottom out these P3's which it should be way over powered for them @ 1ohm! Got the amp cheap enough though that it was still a great deal for the power it does push.
The pic is before rounding the port face