View Full Version : Help me! Alpine S 12" Sub Enclosure

09-02-2013, 06:22 PM
Hello all. I have a single Alpine S-type 12" Subwoofer that needs a better enclosure. I made an enclosure a year ago that I thought was following what alpine recommended, but after remeasuring today, it is too small. After reading around, I figured you guys could help me make a better enclosure than the alpine-recommended one.

Speaker Specs:
Equivalent Stiffness (Vas) = 44L = 1.554 ft^3
Free Air Resonance (Fs) = 34 Hz
Total Q (Qts) = 0.57
Cone Area (Sd) = 479 cm^2

I'm unable to post a link. The manual is titled "OM_SWS-101215_D4_2.pdf"

This isn't for a car, so size isn't a huge concern, but a reasonably sized enclosure would be nice (<3ft^3). My current enclosure drops out at around 40 Hz, which blows chunks.

I don't know a whole lot about acoustics, which is why I've come to you guys. What should I do? I'm hoping to go ported. I reallllly want to get down to the full 26Hz that my sub is capable of, or as close as reasonable.

09-02-2013, 06:37 PM
Where is it going?
How much power is gonna be sent to it?
What kind of music do you mainly listen to?

If you have room for it, a transmission line is the absolute best box you can build. But lets see where its going and maybe we can get one designed.

09-02-2013, 06:53 PM
The system is for home audio. And for loud parties. And, potentially, for a future car application.

The subwoofer is running off of a JBL GTQ 400 amplifier, along with two speakers (which will soon be 6x9 Alpine Type R's). So, I suppose it's getting 150 - 200 watts at max power output. Which is currently more than enough for my current non-car application. If I need to, I'm very willing to buy another amp.

As far as the type of music I listen to, it varies. I'm annoyed sometimes when I'm listening to a song with a great bass line, only to have half of it dropped because it's too low. I don't know if I can get the bass you can feel from a single 12" subwoofer, but if possible, I'd like that.

Is a transmission line really the best? I would think it would lack power due to the absorption of the rear wave. But what do I know?

09-04-2013, 04:26 PM
After some research, it appears my Qes and Qts are outside the range to make a good transmission line system.

Does anyone hae a frequency response curve for my sub? SWS-12D2

Here is a butterworth ported box I designed using ishtek's applet. Do these numbers seem okay? For the volume, I used what it gave me, then subtracted the speaker and port volume. For the external dimensions, I added 1.5" for 3/4" MDF to each dimension.