dc audio xl 12 enclose tuning question. f3?

[throttle98]

Hello. I am new to this forum. I've been reading for a couple hours, searching google ect and am still confused. I just bought me 2 dc audio xl 12's today and am now trying to get some sort of idea for a box. I want a box tuned to 32hz (I think). I love the lows, especially c and s. and lots of bigpimpin's stuff. So now I'm reading about f3 and am just confused as hell. Is this a bad woofer for lows? is f3 and fs the same? People are saying they tune to 32 but play songs that are 26 hz?? doesnt that hurt the woofer? does it hurt if I play it at low volume notes under the tune? Right now I'm running 2 earthquake subzeros and there louddd. running around 2200 rms. This new system will be double that. I'm excited. ha . Anyways heres the specs:( the 12" is the second spec of each category.)

Mounting Depth

6.5"

7"

8.25"

9.25"

Mounting Hole Diameter

9.25"

11"

14"

16.75"

Outside Driver Diameter

11.0"

12.5"

15.7"

18.5"

Motor Width

8.75"

8.75"

8.75"

8.75"

Weight

53lbs

54lbs

56lbs

57lbs

VC Diameter

3"

3"

3"

3"

Displacement

.18³ ft

.19³ ft

.23³ ft

.26³ ft

Magnet Weight

50lbs

50lbs

50lbs

50lbs

Power Handling RMS/Peak

2200/4400

2200/4400

2200/4400

2200/4400

Impedance (Ohm)

D.7/D1/ D1.4/D2

D.7/D1/ D1.4/D2

D.7/D1/ D1.4/D2

D.7/D1/ D1.4/D2

Sd

314.00 cm²

494.00 cm²

791.00 cm²

1159.00 cm²

Vas

12.42 liters

25.77 liters

66.02 liters

144.36 liters

Cms

0.085 mm/N

0.08 mm/N

0.07 mm/N

0.07 mm/N

Mms

171.77 g

213.7g

306.7 g

346.7 g

Fs

41.7

38.5

34.3

32.3

BL

BL 22.73 N/A

22.73 N/A

22.73 N/A

22.73 N/A

Re

3.98 Ohm

3.98 Ohm

3.98 Ohm

3.98 Ohm

Le

5.2mH

5.2mH

5.2mH

5.2mH

Qms

11.24

12.92

16.55

17.6

Qes

0.35

0.403

0.516

0.548

Qts

0.34

0.391

0.5

0.532

Xmax

26 mm

26 mm

26 mm

26 mm

Ref SPL @ 1 watt

85.9 dB

87.5 dB

89.0 dB

91.3 dB

Suggested Sealed

N/A

N/A

N/A

N/A

Suggested Ported

1³ ft

1.5³ ft

3.5³ ft

6³ ft
I'll be running 2 12's and love lows. Could anyone help with with the box. I'd be willing to toss some money around. Especially if theres anyone in nj or ny or pa area who can build the correct box for me. Thanks a lot guys.

[Joe X]

Ok, post max dimensions you can fit for a box, amp and vehicle models. BTW playing below tuning can bottom out a sub but there are way around for that not to happen.

[SnowDrifter]

F3 is the point where your enclosure's output drops off by 3db - pretty much the lowest it will effectively play. This normally occurs at a slightly lower frequency than Fs (I believe the word you were looking for is Fb actually)

Fb is the tuning point of your box

In my own experience, people tend to be tuned lower than they really are. My enclosure, on paper is tuned to 32hz and the box played well down to 27hz. But the measured tuning frequency turned out to be 33hz.

When I shrunk my box, on paper it was tuned to 40hz, but I measured the tuning frequency at 35hz. In a box tuned to 35hz, it's not unreasonable for it to play down to 30-31, which mine does.

So put this all together for someone who doesn't have an IM-SG or clamp meter to measure their tuning frequency. They think they are tuned to 40, but can play low 30s no problem. Or think they are tuned to 35 but are really tuned lower, that's why they(me) can play mid-high 20s

[throttle98]

Hey. Third time writing this.. I looked up the meter and found the owners manual. Its interesting finding what hz your car rattles at and to dampen it. Anyways. Does this tuning have to be done before or after the box is built? anybody in the nj pa ny ct area with this meter? I want to have it tuned correctly. I dont want to play 32 hz songs with the box thats tuned higher and hurt my babies. ha.

my vehicle is a 2001 ford taurus sedan, which back seats fold down. I have 2 brutus 2400's which i'll be running at 1 ohm (2400 rms). The dimensions of my box now are (W x H x D): 33" x 16-1/2" x 21".

[Joe X]

So here is a suggestion 2 DCXL12s on 2 BRZ2400, make sure that you read the notes below the pic:

Enclosure Specifications:

Fb = 32 Hz
Vb = 3.2 ft^3

External Height = 16.5 in
External Width = 33 in
External Depth = 20.75 in

Port Width = 3 3/4 in

Cut Sheet List:

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

External Enclosure Parts:

2 x Front & Back (3 parts) = 33 x 16 1/2

Left & Right Sides = 18 1/2 x 15

Top & Bottom = 33 x 18 1/2

L Port Internal Assembly Parts:

Front to Back = 14 3/4 x 15
Extension = 16 7/8 x 15

Assembly guide (generic dimensions):

Important notes:

- The 45s if you want to do them are 2 1/2" wide except the one/ones inside the port, if you want that let me know.

- All trunk boxes built outside the car need to fit in their way in not just have the right dimensions.

- The port needs 3 3/4" of free airspace in front of it for proper operation.

- Setting your amp subsonic filter to 28Hz is suggested.

[throttle98]

Thanks for the design. Still confused on when I have to do the im-sg tuning. Also anywhere or anyone have the tools in the nj ny pa area? I want this to be bad ass ha. I dont want to harm these babies. Also if the fs is 38.5, if I put them into a 32hz tuned box would it sound worse than a 38 hz box? I am looking to play lots of c and s and decaf stuff

[throttle98]

bump. please,a little help would be really appretiated. I know lots of you guys are pros here. maybe im too much of a newb : x

[Joe X]

You don't need to use the im-sg or other tools unless you want to determine your real tuning if that is important to you (which may be the case for competitors), but be aware that it will change with temperature somewhat. And there's no problem tuning a few Hz lower than Fs, if your are playing decaf and the likes tuning low can help the subs from possible mechanical failure, also setting your subsonic filter can help as well.

[ktroym]

I know this is an old thread but I just wanted to say I built this box with the design above for my 2 DC XLs and all I can say is wow! It really lets these subs beat. I had them in a generic QBox that was suppose to be tuned to 34hz. Thanks for the design Joe X!