Darius Kubarth - December 2007
The original DiSub 12/2 subwoofer designed was released by the German DIY
I decided to modify the plans for aesthetical reasons. For whatever reasons, Mr. Timmermanns shortened the two side walls to the half and made the two drivers visible. Well, that was definitely not desirable by me. There is no problem in making the sidewalls full length as the frequencies produced here have too long wavelengths to care about the 20cm more or less of wood.
Everything else is the same as described and advised in the article mentioned above. The article suggests four different drivers, I went for the best one, the Peerless XXLS 12-8H for a no compromise subwoofer.
Below I'm just giving some build hints, everything else is well described in the article mentioned above.
Preparing for the build
One nice morning the postman had some nice toys for me in his bag. Oh well, not really in his bag as these toys are really big. Let's peek inside.
The 12inch drivers are heavy and well build like tanks. Let's hope they can keep up the good appearance soundwise. I would wonder if not.
As you can clearly see, I used no MDF, but normal wood (spruce wood). MDF has certain characteristics that make it predestined for loudspeaker builds, but from an aesthetic point of view "real" wood with its natural patterns simply wins here unless you are willing to tinker around with veneer. I was not.
The three parts
This is more or less how the box is too look like in the end:
I divided the build in three parts. 1. the upper top and the bottom, 2. the sidewalls and 3. the center part to hold the drivers. It really makes sense to divide the wood work in these parts and build them separately in that order.
One of the sides walls ...
... the center ...
... and combined, but still not glued or screwed together:
Freely placed together it is to look like that in the end:
Now you see why we haven't glued or screwed the the parts together, yet, we still need to add the drivers:
All together now
Now we can glue and screw the parts together and place the filter on the back. The filter is exactly the same as mentioned in the article. No modifications here. The problem with the DiPol design is that it emphasizes frequencies above 200Hz, the filter is to attenuate them. For sure I will not run this subwoofer above 200Hz, but still it gives me a steeper roll off when crossing over at below 200Hz.
Finally the soundcheck
Firstly, this beast is very picky about its location. Everything less than 1m distance to any walls (side or back) will kill the bass. But having placed it right, it simply smokes everything else. No kidding, that's the finest, deepest and especially fastest bass I ever heard. It comes, it hits you and it disappears, so to say. Due to its directional radiation it avoids standing waves in the corners of the room. The bass is in the middle of the room and only there.
To put it clear: Forget everything you can find at your local consumer electronics store. I tried the comparison with various subwofers from well-known manufacturers, but the DiPol simply outperformed them all. I just wish it was not so picky about its place of installation.
Update (June 2008)
I built a second one in the meantime. No doubt, it was a a good choice. Having two of them not only improves the sound stage basswise (don't tell me, you can't locate bass!), but it also makes placing them in the room easier. One left, one right, there you go. I love it.