I'll talk to Gene about how involved these DIY articles should get. I do think there is plenty of room for that here however. I'm no spring chicken when it comes to DIY.
The SDX12 was tested as a kit. After driver displacement and such, its about 1 cubic foot. It's a small box. However, if you model the box, you will see that larger boxes under-damp the response and with ported boxes will cause excess efficiency. It's both an amazing and amazingly challenging driver to DIY with. A ported box for example will end up being as much port as box. It's a very high excursion driver so it needs a large port area. Yet the box is small, an optimal ported box for 20hz tune would be 2 cubic feet. A port with a mouth that is 3x8", which is sufficient for this box, is 78" long. two 4" round ports would also work, thats 83" long. Where is that fitting in a 2 cubic foot box? Requires a lot of added external volume to provide sufficient space for the ports to wrap around.
That is why this driver works best with passive radiators for ported designs.
For sealed, it really works best in a 1-2 cubic foot box, with 1 providing optimal damping. 2 is under-damped but works fine too.
The driver performs well. It really likes/wants a lot of power. The driver can handle, on a dynamic basis, like 2000 watts or so. In testing, we didn't register high amounts of dynamic power, but under sustained SPL testing, we saw the amplifier drawing as much as 1700 watts. I don't think the system we used to measure wattage was totally accurate in that I don't think it was accurately measuring peak power. I don't think it can react fast enough. The numbers we were getting for burst tones was really low and didn't make a lot of sense. We don't normally measure so this was a bit of trial and error.
I personally think the midbass numbers are low and I also think that the sudden rise in 3rd harmonic implies the amp might have been clipping. I forgot to bring my laptop with the Behringer software to the field so when we tested, I wasn't able to monitor clipping in the software, only from the front display. I don't believe the sub would have reached 3dB or more higher, but I wouldn't be shocked if there was another dB or two in there above 50hz. Distortion levels were so high below 50hz that I feel confident those were excursion limits and that we did reach the limit of the driver below 50hz.
Here is a simulation comparison between the sealed and ported subs. This is being fed 2000 watts and the sealed sub has a bit of EQ in line with how I EQed it in use.
View attachment 34248
To make those numbers better match what I measured, add 6-9dB to the measured numbers. The simulated numbers are crude straight calculations of watts in and sound out without any consideration of compression, so its more like peak. It's also assuming 1 meter. That should equate to 9dB but...I also don't know that you would see that fully realized in real life.
I do have access to a Lab Gruppen amp so I may borrow that for a test like this in the future. I have a few DIY subs kicking around I plan to test this coming summer. They probably won't be articles because they aren't kits. They are of my own mad design, but they should be interesting. Maybe a YT video and forum post.
