# Ported box size for newer Type R subwoofers (SWR-12D4)



## mechatron (Sep 26, 2013)

Hi Guys,

I'm just about to get a subwoofer box built up for my SS Commodore sedan and I would love to get some advice from the very knowledgeable and experienced members on here. I currently have one 2012 12" Type R sub (SWR-12D4 1000w rms) in the prefabricated Alpine box (SBR-S12D4 => ie the one with the long horizontal slotted port) and it is powered by an Alpine PDX-M12 amplifier. I now want to get a second 12" Type R sub (SWR-12D4 1000w rms) and get both installed in a custom ported enclosure. I will connect each coil per sub in series (4Ω+4Ω=8Ω) and then connect the two subs in parallel to achieve a total resistance of 4Ω. 

With this new setup, I'&#146;m still planning to use the one PDX-M12 amp to power both 12" subs. From memory my PDX-M12 has a birth sheet of around 1350w to 1400w rms and this power is rated at both 2Ω and 4Ω, so I&#146;'m hoping that this will be adequate to power these two subs properly.

Now I was really hoping to find out what the best size ported box would be for these two 12&#148; Type R subs. I have read quite a lot of information on forums and many people say that the Type Rs sound much better in a large ported enclosure (2.0 to 3.5 cubic feet per sub), but all the info I found was for the older 600w rms Type R subs. So, is this box size of 2.0 to 3.5 cubic feet per sub still recommended for the newer 1000w rms Type R subs (SWR-12D2 / SWR12-D4)? I&#146;m really struggling to find information on the best ported box sizes for the newer Type R subs. Alpine recommends a ported box size of 1.7 cubic feet per sub, but this sounds too small based on what most people have used in the past for the older 600w rms Type R subs. 

So to summarize, can members on here please tell me the following: 
- Optimum box size (cubic feet per sub)
- Optimum port size and the number of ports required
- Whether I should have a MDF divider between the two subs inside the enclosure (i.e. just like having two individual boxes mounted together) or should both subs share the same air space?
- Best tuning frequency, if I like a variety of music (50 cent, Pearl Jam, Bliss N Eso, Evanescence etc)?&#133; I&#146;'m thinking somewhere between 35 and 38Hz. What are everyone's thoughts?

Also the space I have available in my boot is 0.36m x 0.38m x 1m (14.2in x 15in x 39.4in) 

Thank you so much in advance guys.


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## mechatron (Sep 26, 2013)

Also if anyone on here knows of some previous threads on this topic can you kindly post the links below? Thank you


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## Jericho941 (May 24, 2011)

I believe alpine is known for being pretty accurate with it's box recommendations. I'm using 4 of the 8d4 model in boxes close to the recommended specifications and am quite happy. The M12 should be adequate to push your subs to above listening safe volume levels. With cabin gain from a ported enclosure it should be very loud. I have an M12 as well and it was far too intense for listening when used on my old Phoenix Gold Ti10ds (2) in a ported box.

I put the thiele small parameters for your sub (1) into WinISD out of curiosity and here is the gain plot for alpine's ideal box and the "ideal" box of WinISD.










The blue line is the "ideal" box and It's gross volume and port tuning are shown. (2.88 ft^3/ 81.6 l)

The green line is the alpine spec box. I believe that the tuning is supposed to be 29 hz, but I might have misread the spec sheet.(1.71 ft^3? 48.4 l)

Either box looks ok to me as there are no radical peaks but you can see how flat the gain plot is for the larger box and how the roll off is lower.

I skipped over the port length/size as that will vary as you build with a slot, square, or round port.


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## mechatron (Sep 26, 2013)

Thanks heaps for your detailed reply Jericho. In your opinion, what would be the best tuning frequency for me for a variety of music (rap/rock/hip hop)? Would 29Hz be too low?


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## mechatron (Sep 26, 2013)

Is there anyone on here who has put their newer Type R subs in ported boxes bigger than 2.0cu ft per sub? If yes, did you get good results?


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## Jericho941 (May 24, 2011)

While I don't know what your box will sound like if you go above 2.0 cu ft, if you do build bigger wood can always be added inside to reduce the internal volume to what you want. It's naturally more difficult to increase internal volume once built.


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## Golden Ear (Oct 14, 2012)

A friend of mine had his in a 1 cubic foot sealed enclosure and hated it. He then put it in a 1.8 cubic foot ported enclosure and loves it.


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## mechatron (Sep 26, 2013)

Jericho941 said:


> While I don't know what your box will sound like if you go above 2.0 cu ft, if you do build bigger wood can always be added inside to reduce the internal volume to what you want. It's naturally more difficult to increase internal volume once built.


That's true, thanks Jericho


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## mechatron (Sep 26, 2013)

Golden Ear said:


> A friend of mine had his in a 1 cubic foot sealed enclosure and hated it. He then put it in a 1.8 cubic foot ported enclosure and loves it.


That's really good to know Golden Ear. I was very close to going sealed, but luckily decided on slot ported in the end. I'm actually getting a custom sub box made up this week. The space I have now allowed is 39.4" W x 14.5" H x 16" D. I'm aiming for around 2.8 to 3.0 cubic feet where the two 12" subs will share the same air...so hopefully it should be be big enough to sound good


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