Double Checking Box Design

[wafsman]

Just wanting to know if you all could double check my work for me, make sure I'm on the right track. Equipment will be (2) DC Audio Level 4 12's on a DC Audio 2.0K, music played will be Juggalo and Hard Rock/Metal, vehicle is a daily driver. Wanting to know if the specs of the enclosure will work well with the subs, and also what kind of sound this style of setup will produce (i.e. more SQ, more SPL, more lows, more punch, etc.)

External Dimensions - 36W x 15H x 18D

Wood is 3/4"

One open enclosure with 2 flared ports

Ports are 3" x 7.5"

Enclosure in trunk with subs facing out, away from seats and ports facing up towards empty holes where factory 6.5's were

I'm getting about 4 cu ft tuned to about 33 Hz. Any and all help is greatly appreciated.

[wafsman]

Anyone?

[RAM_Designs]

Use 4" aeros instead of 3"ers.

Edited June 13, 2011 by RAM_Designs

[wafsman]

So, other than that everything looks ok? If I change to two 4" ports it tells me that they need to be 13.5" long to get to 33 Hz, if that is true they will not fit the dimensions of the box while facing up. So the question is, if I port facing the rear of the trunk like the subs, will it still be worthwhile to utilize the openings for the stock speakers in the rear deck (that the 3" ports would be aiming towards) or should I seal them off?

Edited June 13, 2011 by wafsman

[PandorasCustoms]

Rear facing ports is fine.

Sealing the trunk from the main portion of the car will have limited effect on the "volume" of this setup, but it will have an effect on air movement.

Also, if you plan on playing heavy metal, you want to look past SPL measurements and look towards Delay.

I have my enclosure tuned to 35Hz and it is sometimes pretty offbeat when a good Double-Bass Drum Solo kicks in.

But my delay is pretty high around those frequencies. As a generic statement, tuning lower decreases Delay.

[wafsman]

So how much port area do I need for these speakers? If I go with slot ported, how much do I need to aim for, right now my new design is reading about 21 sq in of port area for a roughly 1.8-2 cu ft box for each sub.

[PandorasCustoms]

Port Area for a speaker is not a valid calculation.

You can tune to any frequency with any sized port, but port noise may be really bad, and anytime you bump it will sound terrible...

You need a certain port area to generate your tuning frequency and to counter act port noise.

[Supercharged DCs]

Generally, you want 12-16sqin per cube with a slot port. You want 8-12sqin per cube with aeros. Try and get as close to 16 with slot as possible, and as close to 12 as possible with aeros.

[wafsman]

Thanks. So I need more port area to make sure I'm not getting any port noise.

Edited June 14, 2011 by wafsman

[PandorasCustoms]

I could possibly run some calculations for this later today when I get home, but I don't have the time while I am at work. If you don't have an answer when I get a chance, I will look into it.