Box for one 12 Apline type R 1242D

[Jzzt]

Hello guys, this is the sub I have. (Alpine Type R 1242D)

http://www.sonicelectronix.com/item_4281_Alpine-SWR-1242D.html

It will be powered by a 600 watt alpine amp. (The amp has a subsonic filter set at 30Hz)

I posted this up a while ago but it was in the wrong place, it got deleted.

I think the user "Joe X" gave me an answer but I dont quite remember if it was him and I had a couple of questions to ask.

I'm hoping anyone can help me out, or Joe.

This is what he posted before

Enclosure Specifications:

Fb = 32 Hz
Vb = 2 ft^3

External Height = 16 in
External Width = 23.5 in
External Depth = 17 in

Port Width = 1 7/8 in

Cut Sheet List:

* All Dimensions in Inches.
* Wood Thickness is 3/4 for all Parts.

External Enclosure Parts:
Front = 20 7/8 x 14 1/2
Front Internal = 19 3/8 x 14 1/2
Back = 23 1/2 x 14 1/2

Left & Right Sides:
Side 1 = 15 1/2 x 14 1/2
Side 2 = 16 1/4 x 14 1/2

Top & Bottom = 23 1/2 x 17

L Port Internal Assembly Parts:
Front to Back = 13 5/8 x 14 1/2
Extension = 13 1/4 x 14 1/2

Assembly guide (generic dimensions):

Port center line length 30 1/4", and the driver
displacement for the 1243 is 0.1 cubic feet. This may get deleted anytime.

Now on the other thread I had listed 2.0ft^3 and 32Hz because its what I had read in some forums, but I dont know if he went with that just because of what I wrote, do you guys think this design would be optimal for this sub? I have no problems at all making a bigger box if it would perform better. (I like low bass).

I also want to put later the design just to verify the port area and some stuff I wanted to double check. That will be when I get home from work.

Thank in advance guys.

EDIT: Here is one of the questions I had

The one on the left is using the measurements he gave me (Where the port measures 30.25 inches like stated)

The one on the right is the same, except I chamfered the bend at the port @ 45 degrees and put an extra piece in the outer part of the port to keep the bend at 1.875 inches (I dont know how to measure this port???)

which of these two ways is right?

Edit: I have been reading the 45's are just a waste of time for a daily (unless someone else cares to educate me), now moving on the the last! question

Should I round off any edges? or leave everything square?

[Joe X]

Ok I remember you posted in general audio, will give you my take on your questions:

1) 2 cubes @32Hz will give you the low notes, just bear in mind is a single 12" so it will be no ground pounder. Also set your subsonic filter to 27Hz or so to protect the sub.

2) port area used will result in 23 m/s peak airspeed on your port at rated power, that is enough area to avoid any port noise.

3) the net volume is the top recommended, you would increase net volume if you were in low power.

4) if you don't want to do the 45s just don't do them but do round the inner corner at the port turn and both the internal and external ends. I draw them so people that want to do them have a look.

5) the center line of the port with a 45 is slightly shorter than the one without it but the difference is so small that can be *usually* ignored.

Hope the answers are what you expected.

[Jzzt]

Thanks again for the reply Joe, already got the mdf in the backyard this weekend it will get built.

I will round off the corners, I have just never done rounder corners or 45s before so I was just being cautious to make sure I didnt mess up.

Since the amp will be feeding around 600rms instead of 500 should I be concerned with anything?

[Joe X]

No, the sub will take 600W easily, just make sure you have your subsonic filter engaged and that you set your amp gain properly and check that your electrical is in good condition, to have a rough idea if your electrical is doing ok do the following: with the amp playing some bass loudly and the car running, the voltage at the amp power terminals should stay above 13V.

[Jzzt]

Yes, the subsonic is @30Hz

http://www.sonicelectronix.com/pictures_new.php?id=3733&picture_id=106616

Gain is as low as it goes which is +0.

And one more question since I'm on this, I have done some research on google but only have vague answers, what is the "lp slope" on the amp in the picture above.

Once again thanks for all your help

[Joe X]

Ok you need to go through a gain setting procedure to set your amp gain, on the low pass filter, it determines at what frequency you want to crossover to your front stage speakers, so the high pass filter on the speakers amp should be set around the same frequency, the LP slope will determine how sharp the drop in gain will be, if set to 24 dB the transition to your front stage will be fast, LP settings will determine how the front stage will blend in with your bass stage, the proper settings depend on the speakers/subs involved and personal taste.

[Jzzt]

I get it, hopefully this weekend I'll have everything set up, I'll post an update here if I finish it.

[Joe X]

Ok, If you have any questions let me know. No notion if you have built boxes before, recommended to use Titebond II wood glue and MDF/drywall screws, silicone caulk after it dries to avoid leaks.

[Jzzt]

Thanks Joe, another question that maybe you or somebody else can help me out with.

I want to purchase some sound dampening cld tiles from http://www.sounddeadenershowdown.com/ for the trunk of my car, I have read good stuff about this but have not been able to get in contact with the seller, Don.

Does anyone have any experience with this product, I dont know another way to contact him except his email, it has been a week since I contacted him.

edit: was just able to get in contact with him, nvm. Seems he did not receive my first email.