Help building an optimal sealed enclosure for a 12" sub.

[nexttothemoon 0]

I've just bought a new Pioneer TS-W308D2 dual 2 ohm VC subwoofer. This is the first sub I'm building an enclosure for so I wanted to keep it simple the first time around and stick with a sealed box to keep things easy and relatively foolproof. I may go ported in the future but that's another build for another time.

I have two different 2 channel amps (Kenwood KAC7204 ~500 RMS bridged 4 ohm for the subwoofer and an Earthquake T1000W/2 ~200 RMS x 2 channels 4 ohm for the 6.5" comps that I'm putting in the front doors (I'll keep the gains turned well down on the amp to the 6.5 comps).

I've looked at the Pioneer manual for the sub and it has the following stats for a sealed enclosure:

Minimum Sealed enclosure size: 0.85 cubic feet

Maximum Sealed enclosure size: 1.75 cubic feet

Recommended Sealed enclosure size: 1.25 cubic feet

These sizes include the speaker displacement.

Here are all the Thiele stats for the sub:

Nom. Dia.(In) 12

Qts 0.48

Qms 14.11

Qes 0.50

Fs [Hz] 33.7

Vas [l] 36.16

Vas [ft3] 1.28

Vd [l] 0.400

Vd [ft3] 0.01412

Sd [m2] 0.04597

Sd [ft2] 0.495

Revc [Ω] DUAL1.5

Levc [mH] (2000Hz) 2.18 (4Ω) 0.65 (1Ω)

Xmax [mm] 8.7

Xmax [in] 0.34

Zmax [Ω] 99.13 (4Ω) 24.81 (1Ω)

BI [Tm] 16.07 (4Ω) 8.04 (1Ω)

Rms[Ns/m] 2.773

Mms [g] 184.95

Cms [m/N] 0.00012

Mg.Wt.[g] 2350

Flux Density [Gauss] 6800

Hag [mm] 10

Hag [in] 0.39

Hvc [mm] 27.4

Hvc [in] 1.08

VC.Diameter [mm] 55

Eff [%] 0.27

S.P.L. [dB] 91.0

R.M.S.Power [W] 400

M.M.P. [W] 1400

Sp. Displacement [l] 2.16

Sp. Displacement [ft3] 0.076

Recom. Enclosure [l] 35.4

Recom. Enclosure [ft3] 1.25

F0 (in Cabinet) 47.9

Q0 (in Cabinet) 0.682

I also ran the numbers through WinISD and it calculated that the optimal sealed enclosure size for this sub is 1.093 cubic feet and gave the optimal box size as follows:

13.95" wide

21.46" high

8.93" deep

I'm using 18 mm thick MDF to build the box which is equivalent to 0.71 inches.

What I'm wondering as I'm new to this is which size within this range would be best for a sealed enclosure. Pioneer gives a large range of sizes to use from 0.85 to 1.75 cubic feet and their recommendation is basically right in the middle of that range @ 1.25 cubic feet whereas WinISD gives an optimal of 1.093 cubic feet.

What is the benefit of going as small as 0.85 cubic feet or as large as 1.75 cubic feet?

I'm basically looking for 50-50 SQ/SPL and I realize going sealed vs ported is giving up some SPL hopefully in favor of some SQ... and that's fine with me for this first build. What I'd like to know though is how the size of the enclosure within that range from .85 cubic feet to 1.75 cubic feet effects the SQ and SPL.

What size would you all recommend? What would sound the best and make optimal use of the sub for SQ/SPL in a sealed enclosure? Any advice is appreciated. Thanks in advance.

[KU40 173]

Well since you used winISD you should have seen a lot of the differences in the different boxes. You should have seen the difference in frequency response between a large and small box, that being the larger box has more low frequency extension. Larger boxes are also more efficient, but power handling is reduced. You really won't hear a difference between the 1.1 cube box winISD recommends and the 1.25 cube box pioneer recommends as optimal.

You don't have to use the exact box dimensions it gives if that shape isn't optimal for your location.