# Help building a good SQ sealed enclosure for a single 12" sub.



## nexttothemoon (Jan 3, 2010)

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.


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## sonikk71 (Aug 13, 2009)

I know this may sound strange but I have a few questions for you before I answer your question, What car is this going into? What kind of music do you mostly listen to? Finally what is your favorite color?


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## nexttothemoon (Jan 3, 2010)

This is going into a 1994 Mitsubishi Lancer 4 dr sedan. It's for my daughter and she listens to a mix of music... Rock and Rap mainly but a mix from other genres as well. My favourite colour is blue.


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## sonikk71 (Aug 13, 2009)

Based off the replies you gave I would stick the winIsd design. There wont be too much difference between the recommended Pioneer enclosure of 1.25 and the 1.093 box other than the bigger sealed boxes will play lower and have a lower overall "Q" . However based on the fact that this is for your daugther and she likes rap and rock, the 1.0 to 1.25 cu foot-ish boxes will keep the "Q" up so she will get the "bump" that most people love. Not saying this configuration will sound overly boomy at all, but I guarantee if you go for the 1.75 cu foot sealed enclosure it might be a little too clean for her taste (most average people dont really like a real low "Q" I have found.... as opposed to audiophiles) Remember to use a liberal amount of wood glue and coarse thread screws (to hold it together while the glue dries). I would also say to use some stuffing and experiment with varying amounts. Start with around a pound but dont be afraid to tweak with it. This should make your daughter happy. Oh and regarding the color question... Nice to see someone else on here that doesnt take themselves too seriously.


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## DynaudioNut (Jan 1, 2010)

Sealed 1.25 or if you want a little more rumble ported. I listen to all genres of music but I have a tendency to listen to more R&B, Rap and Jazz so sealed gives me the best all around sound. However, I did like the depth of sound when I used a ported box.


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## comfy_shoes (Nov 26, 2009)

I built my sealed sub enclosure for an infinity reference 12" 1260w at 1.3 cu/ft with about a pound of polyfill and sprayed the inside of the enclosure with a popcorn acoustic spray.(looks like ceiling stucco) I used 3/4" mdf ,pl premium and braced it well. I found that the box vibrated . that didn't sit well with me. so I put another layer of mdf makeing it 1 1/2" thick. you wouldn't belive how much more dynamic the sound was. density plays a large roll in transferring the forward wave out of the sub. (heavy box however) 

when you vary the volume of the box, it affects cone excursion and overall sq.....with that said most here enjoy a small box to keep it tight. however the larger or smaller you make the box it affects the "Q" ........is that the same "Q" ....as you would adjust on a parametric equalizer? how would a small sealed box recreate a kick drum in comparison to a larger box?. would the larger box be more dynamic? (ex raw, realistic, live,earthy) 

sorry to piggy back on OP's thread. opinions here may help his cause!(opinions about my post that is)

I know that alot of people feel that 3/4-1" mdf is more then enough for a sub enclosure. however, I have noticed with extreme home stereo systems. ex. 50,000$ plus, alot of installs use custom concrete sub enclosures. so keeping that in mind I made my box 1 1/2" thick and the sound improvement was phenominal. has anyone every went thicker then 1 1/2" thick here?


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## nexttothemoon (Jan 3, 2010)

As this is my first build... I figured the standard 3/4" MDF would be fine. Now you all have me worried.  Brace it up... concrete it... and make it 2 feet thick... yes sir.  

All joking aside... this is all a learning experience the first time out so if it doesn't all work out perfectly I can always make another one and try for better results next time. Thanks to everyone for all the advice and keep it coming if there is anything else useful to add.


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## comfy_shoes (Nov 26, 2009)

3/4" will be fine enough. some people just experiment .....no harm keeping it simple. thats usualy the best anyway!


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## justinhamill (Jan 14, 2010)

nexttothemoon said:


> As this is my first build... I figured the standard 3/4" MDF would be fine. Now you all have me worried.  Brace it up... concrete it... and make it 2 feet thick... yes sir.
> 
> All joking aside... this is all a learning experience the first time out so if it doesn't all work out perfectly I can always make another one and try for better results next time. Thanks to everyone for all the advice and keep it coming if there is anything else useful to add.


Hi, just to say: as a builder of hi-fi transmission line speakers, bracing across the enclosure has dramatic effects on resonance and the need for thicker panels.


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## kb240 (Feb 8, 2009)

run the the numbers through winisd again, this time with a port. see if the volume is near the same as the sealed range you have to work with. if it is, aim closer to that number, so if she wants to get louder later, you just need to drill for the port tube and drop it in... no new box building needed.


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## SmallSoldier (Aug 8, 2007)

justinhamill said:


> Hi, just to say: as a builder of hi-fi transmission line speakers, bracing across the enclosure has dramatic effects on resonance and the need for thicker panels.


Could you please elaborate?

Thanks!


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## grga22 (Oct 11, 2010)

He meant that sound waves going arround the sealed enclosure would make resonance if the sides are too thin.

If I got it right... 

But, in my experience, I think it's just fine... I needed time to think since I'm on metric system...  And, I think you should try a ported enclosure for that sub. If I remember correctly, It's around 35 liters...


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## Chaos (Oct 27, 2005)

This may have been more constructive nine months ago for this thread, but in general, bracing enclosure walls is a worth the extra effort. Anything you can do to dampen vibrations is good.


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## SmallSoldier (Aug 8, 2007)

Chaos said:


> This may have been more constructive nine months ago for this thread, but in general, bracing enclosure walls is a worth the extra effort. Anything you can do to dampen vibrations is good.


Thanks for the answers... I misunderstood his post and thought he meant that by bracing the interior of the enclosure, you could have issues with ressonances... I try not to ask questions before searching and that's how I got to the topic, I apologize... didn't realized it was that old


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