Ported enclousure for two Alpines R2-W12D4

[SPLdin]

Hello forum. I am planning to pull the trigger on two Alpine Type Rs from the last generation. I really like the way type r's sound, because I used to have a SWR-1243D in a 2.1cuft box tunned to 33Hz, which I ultimately regret selling. The main question I have is about the enclousure. Specs say that 1-1.5cuft is the recommended volume for a ported box per piece. Isn't that too small? I ran a simulation on WiniSD and I could see that bumping volume from 1.5 to 2cuft increases output throughout the whole HZ range, wihtout making the box "peaky ". I know that there are way more factors than box volume at play and maybe these subs will perform better in a lower volume. My goal is to have a good output from 28-29 to low 40s, tbh I am not a fan of peaky outputs. I plan to run a single 6inch flared aeroport. Thanks!

 

[Joe X]

The new swr 12d4 will work on smaller boxes than previous versions, to determine the volume to use enter both the old and new models in winISD and change the volume of the new version to approximately match the curve the 2.1 cubes plot of the old one you have and use the same port area you had in your old box. Of course you need to check the excursion plot at the power you intend to use your new subs to be within Xmax, now you can build to the specs you just obtained.

[SPLdin]

Didn't thought of making that comparison, thanks for the suggestion. Seems that the newer R Type is matching the curve (all things equal) at around 1.7cuft. That makes me wonder if increasing the volume to 2cuft+ would yield more dB throughout most of the Hz range or it will peak at a certain frequency? WiniSD is showing that it will increase dB without being peaky but not sure if that would happen in the real world. I can comfortably fit a 4.5cuft box for two subs, if that means I can get the most dB output at (high 20s - low 40s). Forgot to mention that my amp is Taramps HD3000, I know it's an overkill but I like to have a headroom and adjust the gain accordingly instead of running the amp to it's limits.

Edited February 3 by SPLdin

[Joe X]

You just need to make sure your subs do not go over Xmax at the operating power, but since your amplifier exceeds by far the RMS of your subs you will have to be very careful not going too far, generally oversized enclosures and sub overpowering in a hazardous mix with a very likely outcome of subs mechanical damage so you need to set the gain of the amp not to the clipping point but rather lesser that the subs can can tolerate.

 

You can find maximum power in a similar way as before, in WinISD up power until Xmax is reached in the enclosure size you chose and you can clamp the amp to roughly reach that power and set gains accordingly so you can't go over the limit on normal use.

[SPLdin]

Xmas remains under 20mm even at 2+cuft per sub and 2k WRMS total. I am not sure if Type Rs can handle more than 1k WRMS a piece for a long time. I guess I'd need to hear both setups to make up my mind. Thanks a lot for your help!

Edited February 6 by SPLdin

[Joe X]

Subs get stinky when they had enough power, but I wouldn't try that method on type rs, that is a method more adequate for SPL drivers.

 

BTW make very sure you entered valid data to WinISD or you may be led to the wrong conclusions.

[SPLdin]

Oh, definitely. I'll aim in the region of 8-900w for day to day listening.

 

Had to look up how to enter data in winISD as it was throwing me off. I got the t/s parameters from Alpine website. Should be good enough, although no two speakers are exactly the same.