Center Slot ported box for 2 Rockford Fosgate P3D4's, tuned for everything from rap to country...35hz???

[duckcmmndr]

I have been out of the sub box building game for awhile and just picked up two P3's that I want in a ported box that will get low.  It's going in the back of a ford expedition, so size and shape really don't matter much.  My last box I built about 10 years go for a 10" Alpine Type R.  I followed Alpine's guidelines for the ported box and while it sounds good, the really low notes fall off and you can't/feel them.  It could be the speaker, the tuning of the box or a combination.  I don't want that to happen this go around.  Back in high school I had 4 Punch 15's in sealed box with 2.5 per and that thing would play any note you sent to it...would love for these two new 12's to play anything you throw at them.

 

Any help would be greatly appreciated.

[Joe X]

The best way to get flat response is what you did, run an array of high diameter subs in sealed if you don't mind the larger box.

 

To me two standard 12s in a large vehicle cabin is insufficient but if you have to work with them then the box is the way to get them going lower by tuning low with proper port area and going with the maximum allowable internal volume.

 

Once the box has the ability to play low you can use a DSP to try to even things out if needed, and hopefully you will like the outcome.

[duckcmmndr]

3 hours ago, Joe X said:

The best way to get flat response is what you did, run an array of high diameter subs in sealed if you don't mind the larger box.

 

To me two standard 12s in a large vehicle cabin is insufficient but if you have to work with them then the box is the way to get them going lower by tuning low with proper port area and going with the maximum allowable internal volume.

 

Once the box has the ability to play low you can use a DSP to try to even things out if needed, and hopefully you will like the outcome.

 

Thanks for the quick response. 

 

I have room, do you have a enclosure design for two P3"s that will accomplish what you said?

 

I like this setup...but this is not a lot of internal volume, it might be enough...I don't know. 

https://www.stevemeadedesigns.com/board/topic/169035-need-an-enclosure-design-for-2-fosgate-t1-12s-please/

 

I do have a couple of questions about this as well:

 

1.  If you add the 2.5" angles in the corners, would you not have to increase the internal volume to compensate for the space they take up?

 

2. On a ported box is it recommended or beneficial to line the interior with a layer of poly?

 

[Joe X]

1) Yes you have to account for the displacement of 45s but in most cases this displacement is very low.

 

2) If you add damping to the interior of a ported box it results in a reduction of output around tuning, it also can reduce port noise in a misdesigned enclosure, it is beneficial for flatness but it will reduce output and therefore usually is not used.

 

I will look into the modeling of the P3s however it would be necessary for me to know what amp are you using.

 

 

 

Edited April 21 by Joe X

[duckcmmndr]

On 4/20/2024 at 7:25 PM, Joe X said:

Yes you have to account for the displacement of 45s but in most cases this displacement is very low.

Looks like on the box in the link above the 2.5" wide triangles account for 26.17 Cu. In. per corner for a 16.75" internal height.  The one in the center of the ports is double that, so 52.34.  Does the 52.34 take away from "Port Volume"?

 

 

On 4/20/2024 at 7:25 PM, Joe X said:

I will look into the modeling of the P3s however it would be necessary for me to know what amp are you using.

 

Thank you...that would be much appreciated.

 

I will be running a Rockford T10001BDCP and with the speakers being the Rockford P3D4 12's, I plan on sending a 1 ohm load to the amp.

 

Is it ok to run speaker wire from one sub to the other through the port along the back...or is better to put two speaker terminals in?

 

My max build width is 45"...height and depth really don't matter.

 

Thanks again...looking forward to what you come up with.  I am excited to get started.  The subs are arriving today and I will try to sneak off work early enough to get a sheet of 3/4 MDF today or tomorrow.  I will be posting pics along the way!

Edited April 22 by duckcmmndr

[duckcmmndr]

The Subs came in yesterday...they look beefy to say the least.  I picked up a sheet of 3/4 MDF this morning along with some wood glue and screws.  The amp is enroute and scheduled to arrive on Thursday.

 

I ran all my power wire over the weekend.  I ran a 1/0 from the battery and split into dual 4ga. for the two amps.  Last night I installed my 4 channel amp and replaced my factory front door speakers with a set of JBL Stadium Series 6"x8" component speakers, 862CF.  Just need to get started on the box for the subs now.

 

I can't wait to see how this sounds.

Edited April 23 by duckcmmndr

[duckcmmndr]

I thought my Type R 10 was hefty...these P3 12's are massive!

 

1/0 power wire to the distribution fuse block under the back seat.

 

[Joe X]

Here is a box made to be similar to the one you linked but a bit better for the lows and the cutsheet can be completed just with a table saw and a jigsaw, no need for router:

 

Power: to sub(s) rated, amp subsonic filter to 28Hz, minimum port clearance 4", figure is just an assembly guide:

 

 

 

 

[duckcmmndr]

2 hours ago, Joe X said:

Here is a box made to be similar to the one you linked but a bit better for the lows and the cutsheet can be completed just with a table saw and a jigsaw, no need for router:

 

Power: to sub(s) rated, amp subsonic filter to 28Hz, minimum port clearance 4", figure is just an assembly guide:

 

 

Awesome...thank you so much!!!

 

The amp is coming today, I can't wait to get started on this.  I have a work trip that just came up...so I will be out of pocket till next Wednesday

 

Couple of questions:

 

- Are the triangles 2.5" wide like the other design?

 

- The double triangle in the center of the port...I assume the clearance there is 1/2 the port width, so 2"?

 

Thanks again for putting this together, I really appreciate it!

[CFD]

Joe X design is a good ported box. Corner 45s don't do much for a subwoofer box besides brace it and eat up internal volume. If you wanted a similar design with a bit more internal volume then I do have one free on youtube. Feel free to do basically whatever with it.

 

 

You could also try to design a mass loaded transmission line with offset driver/stub. It's basically a lot like a ported box but attempts to cancel resonance in the enclosure to give more bandwidth.