I dropped by TC Sounds’ web site today and couldn’t believe what I read – they were doing a blowout on their dB-500 12″ subwoofer for only $75. Even though this driver is considered entry level from TC Sounds point of view, there’s a lot of high-end features that make it worth twice that price. I couldn’t pass it up, and knowing that TCS probably wouldn’t have this driver around for very long, I decided to buy it. I had barely even looked at the specifications or even ran any models to see how this sub would perform before clicking the Add to Cart. I love that so many companies accept PayPal now for making purchases, it makes buying things so much easier.
So later on today I sat down with Unibox and modeled up the dB-500 to see what kind of performance this thing is going to deliver. It looks as though anything between 3.0 cu.ft. and 4.0 cu.ft tuned anywhere from 19-23Hz is going to yield sub-20Hz f3’s and over 110dB SPL over most of the critical subwoofer frequency band. The smaller box (<3.4 cu.ft.) results in some peaking, a dB or so around 22-24Hz with a higher f3, while the 4.0 cu.ft. box has an impressive f3 of 18Hz. It appears as though the optimally flat response is achieved with a box that is 3.7 cu.ft. and tuned to 20.5Hz which yields an f3 of 18.5Hz and 112dB from 23Hz on up. That looks like it will be the design to shoot for. Now it's time to figure out if I have the room for a box that big, especially after taking into consideration the port.
The recommended port diameter for a driver such as this (that can move a lot of air) without worrying about port noise and turbulences is at least 6.0". That could be tricky because a 6" port needs to be 44" long to tune a 3.7 cu.ft. box to 20.5Hz. Since I don't intend on making the box that long in any direction, I'll have to throw in an elbow in there. One should be enough, I want to avoid using two if I can. A port that size takes up over 1400 cu.in. of volume, so it requires the gross external volume of the box be quite a bit larger than just the 3.7 cu.ft. needed for the sub. In the simplest terms, a 22" cube made from 3/4" MDF with sufficient bracing would work. I'd like to build this sub into an end table for the family room. We need something on that side of the sectional, so if I can design the sub around the idea of making an end table, I should have plenty of room to get the box the size I need. I'm thinking about powering it with a Bash 500W plate amp from Parts Express. Anyway, I'll get some plots and pictures up soon, this sub is going to rock!
