Last month I flew to Utah to help my brother Steve build some subs to finish out his sweet basement home theater. After months of design and indecision we settled on a concept that we both felt would best suit the home theater and provide a rocking movie-going experience. And this is the design, start to finish, in a nutshell. Without too much extra blabbing by me, here it is…
We built four (4) 90 liter sealed sub enclosures to house a set of 15″ TC Sounds LMS series subwoofers. The subs are powered by four (4) Crown XLS 2500 Drivecore Series amplifiers. The subs/room is EQ’d with a Behringer DEQ2496 Ultracurve Digital EQ. Just about everything was bought from my all-time favorite place on the planet – Parts Express. The heart of the system is a Marantz AV8801 A/V pre-amp/processor. The LCR and surround sounds are provided by Klipsch THX UltraII reference speakers. The projector is a JVC DLA-X70R with 4K e-shift D-ILA and 80,000:1 native contrast ratio. The projector itself warrants its own blog entry. For now, however, I’m just focusing on the sub build.
We threw together a design and picked out the speakers and amps. The Crown amps were picked for their output power capabilities which mated well with the TC Sounds drivers and their ability to run extremely cool and extremely quiet. Each amp is running bridged mono into 4 ohms and drives the two (2) two-ohm voice coils in series of each driver. This presents the maximum power possible from each amp to each driver without being excessive or wasteful. These amps are not your cheapest when it comes to $/watt (such as the popular Behringer models), but they are an exceptional product that worked very well in this application.
Each XLS 2500 amplifier is running off its own dedicated 15A breaker from the home’s main panel. The speaker wiring from the amps is 12/4 AWG in-wall speaker wire with two of the 12 gauge wires in parallel for each of the (+) and (-) polarity from the amp to the driver. This minimizes losses and maximizes the use of the 12/4 speaker wire.
We had 3 days to build and install all four subs and 1 day to do the EQ and room calibration. We worked hard for basically 3 days straight, putting in nearly a 16-hour day on Saturday, working from 8AM to midnight and at least 12 hours on the other days. It was crazy, but I couldn’t go home until it was completed. For me it was my dream job, getting to build speakers all day long. What more could you ask for?
The theater consists of a 14″ deep false wall and a perforated 160″ screen. The subs are recessed back into the wall and sit flush to the screen. All four subs sit front and center. The sub design can be found in the pics below. It is not your typical enclosure shape, but suits the purposes of this theater in maximizing the stage space by only being 13-3/4″ deep. The rest of the volume is made up in the width of the enclosures which are 37″ wide. The height of each enclosure is 19″. Total internal volume is about 90 liters or 3.1 cu.ft. This is a good size for the LMS series drivers.
Of course I couldn’t wait to break out my measurement equipment and see just what (4) 15″ subs looked like in terms of frequency response. I didn’t do any max SPL tests even though I had my SPL meter, we just didn’t have time to do it. We did watch a few movies though and ear-piercing levels and I can truly say that this system sounds phenomenal. I won’t even attempt to describe it, but it truly sounds amazing, definitely the best home theater experience I have ever heard and seen. The bass is unreal, it’s deep, it’s powerful and it shakes absolutely everything. The sound is rich and full. And the measurement plots show that we were able to achieve basically a flat response +/- 3 dB all the way down to 15 Hz at the listening position. And that wasn’t with a ton a EQ at the low end either. We tamed some of the peaks and flattened the response without hardly any low-end boost. While the sealed enclosures themselves rolled off as expected, the room gain more than made up for it. Not to mention there are (4) 15″ drivers. So once we killed some of the higher-frequency peaks, the subs had no problem going low. Room modes occurred at around 60 Hz and we did not alter those with the EQ.
For now I’m just going to throw up the pics, so feel free to click through them and you can see the theater take shape as well as the sub build and install. I should have taken more pics overall of the theater, because there is so much more going on than just the subwoofers. In fact, now that the acoustic panels are installed you can’t even see the speakers. Just the great craftsmanship of the woodwork throughout the room and that massive 160″ screen. It looks as good as it sounds. And it sounds amazing. I can definitely recommend this kind of setup for someone looking for an awesome subwoofer project. I know there are lots of different ways to get bass into a room but this one was simple, elegant, affordable, tune-able and in the end matched extremely well with the rest of the speakers in the system. My brother was happy in the end and so I was happy. Now to beef up my own theater with a couple a 15′s, well, maybe another day.