Well I’ve started designing another massive subwoofer for a friend at work. We started talking about audio and speakers a few months back when he’d mentioned he was looking to buy a new sub for his up-and-coming home theater. So of course I chimed in and said, “Hey, let me design one for you.” So we kicked around the idea for a few months, and watched the deals and sales over at TC Sounds come and go. Then finally this past weekend he dropped off a receipt on my desk showing he’d just paid for one 15″ TC-3000 Subwoofer. Nice. And so the project has officially began.
After running some simulations in Unibox 4.07, we’ve basically decided to go with a standard QB3, 4th order alignment which requires a 6.0 cu.ft. (170L) box tuned to 20Hz. This yields a -3dB point of 19Hz and a very flat frequency response pretty much all the way down to 21Hz. The question may arise, why not tune lower (EBS)and sacrifice some upper/mid bass performance for some crazy bass into the teens? Well two reasons – box size and port length. What I’ve modeled so far with the 170L enclosure, we’re looking at two (2) 6″ ports which are 58″ long each. Ports that big and that long take up a whopping 2.2 cu.ft. (63L) of space inside the enclosure. To drop the tuning frequency 1Hz requires each port be an extra 6″ long. To drop 2Hz requires 14″ extra inches. And to drop 3Hz, to a tuning of 17Hz, would require each port to be 24″ longer. Seeing a pattern here? I have yet to figure out how I’m even going to fit the two 6″ ports into this box that are long enough to tune it to 20Hz, let alone tune it much lower, but I’ve got some ideas. Besides 20Hz models well in this size enclosure with no hump or drop in Fr. If we have to, we can use just one (1) 6″ port, but the port noise is going to be on the high-side. That’s why the whole port situation is still up for debate. The size of the box is already getting big, so I don’t want to have to change that too much, but the ports…we’ll just have to see.
The second thing I’ve been looking at is the amp to drive this sub. Now where can we get enough cheap power to drive a sub of this magnitude? From reading around and checking out a few places, the Behringer EP2500 is a very popular amp with the DIY crowd and is capable of pushing just about 2kW of real-world power into a single bridged 4 ohm load. That sounds like it should just about do it. And for a price of only $349, it’s probably the most bang-for-buck you can buy. And Parts Express carries it too which is nice, since I like buying all my speakers from them. Well with the exception of the TC Sounds sub, but for just about everything else…it’s PE all the way.
And so the project design phase has begun. I’ll be update this blog as well as Audio Innovation with the details of this build-up, but it should be fun and at if nothing else, give me something to write about.