I have a 1566 cubic foot (12' W x 9' H x 14.5' L) dedicated theater in my new home (converted bedroom). It is prewired for 5.2.4, and I am wanting to use DIY Sound Group speakers and subwoofers. I will have an AT screen on the 12' wall and probably will construct a baffle wall. There will be one row of seating at 10' to 11' from the screen. Below is the setup I am currently considering: 3 - HTM-12 speakers behind the screen. 2 - Surrounds, HT-6/8/10 or retail in-wall 2 - 18" or 15" sealed subwoofers (under the screen, since I need to minimize the space behind the screen) 4 - Volt, HT, or retail in-ceiling I am looking for comments/recommendations on whether these speakers are a good choice, or, if something else might be better for the size of my room. I would like to stick to designs that have flat packs and premade crossover assemblies to make the project easier to build and complete. My current speakers are older AV123 Onix Rocket towers and center, and dual sealed 10" subwoofers. While investigating what speakers might be able to be put behind an AT screen, I started getting interested in speakers with higher sensitivity such as "smaller" commercial theater speakers like the QSC SC1120 and JBL C211. However, the HTM and HT speakers seem to be more suited to the size of my theater. One of my current subwoofers is not working, so they are my most immediate need. To me, it looks like subwoofers would also be a good first build? Thanks, Brad
I'm looking at the same subwoofer situation where I'm trying to cook up a pair of shallow subwoofers to stick to against the wall in between a trio of HTM-12s. My goal is to get something that's got a flat response down at low as possible, reasonably loud, and not require a huge amount of amp power. Best option I can work out that I think best suits my situation is a pair of subs based upon the Dayton RSS390HF-4. Every choice in design is a compromise and driver selection is no exception. This thing's a 15" that's shallow enough to fit a depth similar to an HTM-12 whereas I cannot find a useful 18" driver that's a viable candidate. My next best choice was the Ultimax UM12-22 driver. It has a huge Xmax but if less plus based upon the Qtc it's a driver that really shouldn't be used in a ported box and I'm not looking at sealed. Sealed certainly has its advocates and a shallow rolloff, but for HT duty I'm sitting in the vented camp. Generally the higher efficiency sub drivers all have higher resonance frequencies a lower Xmax. The RSS390HF-4 is so far the best candidate I can find with a mix of big Xmax, low Fs, good power handling, decent efficiency, and biggest swept area while having a 7 or 8" mounting depth. I've fiddled with WinISD and distilled out a 6.8 cubic foot cabinet with a 17 Hz tune. One vent solution is a 8" x 3" slot 29" long. This will also require a MiniDSP in between the receiver and the amps with a 2nd order Butterworth high pass filter at 17 Hz to protect against excessive excursion. I'm assuming 500 real watts of power. Your design can be smaller, it can be bigger, just play with the size and tuning while keeping an eye on excursion and port length. At some point a port becomes impractically long, but make it big enough while trying to get it under 17 m/s port velocity. Set the signal to a wattage that you're willing to make happen and visit the filter section to put in a high pass to control excursion would without compromising the low frequency response too much. From there, just make the box fit the space. I'm choosing to build up instead of sideways to keep the driver away from room edges. For an amp in thinking probably one Behringer A800 per sub. The A800 has no DSP whereas the Behringer X000D or Crown XLS products which have an internal DSP cannot set a high pass below 20 Hz. Could also use Bash plate amps, but they have DSP built in which can only be modified by soldering in different resistors. When it comes time to bust out the Room EQ Wizard you'll be glad you've got a MiniDSP in hand. Once you start modeling drivers in WinISD and look to bang down that excursion hump you'll see why this is important.
Thank you for the reply. Will your enclosure be 9.75 deep? I have a lot to learn before I could consider designing my own sub.
Yeah, 9 or 10 inches deep. I'll be toeing the L and R speakers out a bit so I might wind up with more like 11 or 12 inches, but for now I'm holding firm on 9" for the box because the driver surround takes up space too. You can make the enclosure pretty much whatever shape you need it to be, just make sure there's about an inch or so behind the driver so air can flow out the hole in the back. You also don't want the back of the driver to point at a port, but that's really only a problem for people who build sonosubs. Physical volume is what matters, not really shape so long as it's one contiguous space and not a chamber and then a port to another chamber. A more regular shape will take up less material per given volume. Play around with WinISD. I find it easiest to import drivers by going to loudspeakerdatabase.com and pulling down their WinISD files and dragging them into the load dialog. You can also enter them yourself if the particular driver you're looking for isn't, such as in the case with the DA Kraken. This Home Theater Gurus YT channel is pretty good. It's not gospel by any means and he's not perfect, but it's a real good place to start. He also has 4 videos (episodes 21 through 24) on room treatments that are really wonderful and crams down everything useful you might get out of the Floyd Toole book into quick and easy to consume videos. Highly recommended, if you heed no other advice I've mentioned then at least watch those 4 videos.