A couple of years ago, I fell into a dangerous addiction. At the time, I had a Polk PSW110 subwoofer, which I had purchased from Best Buy. I knew very little about subwoofers, and I thought the 10" Polk sounded good, but every now and then I craved a more tactile experience—I wanted bass I could feel. The main problem was my budget; I was not in a position to spend lavishly on a new sub, but I knew I wanted something much better than what I had. One day, as an experiment, I opened up the Polk and wired a pro amp ( Crown XTi-1000 ) directly to the driver. The result was profoundly better sounding; from that point onward, I knew that I would have to learn more about subwoofers.That impulse led me to the AVS DIY Speakers and Subs forum . AVS was already my go-to source for DIY screens and projectors, and I was thrilled to find a large community of DIY subwoofer enthusiasts. Since I already owned a decent amplifier, I decided to learn more about passive subwoofer designs. There is a lot to learn, but subwoofer design is easier than ever, thanks to software tools that aid in designing the right enclosure. After hanging around in that forum for a while, I started to notice some characters—bass addicts, if you will. These enthusiasts are willing to go far beyond what most people would consider reasonable in the name of low-frequency transduction.Take AVS member Austin, aka popalock . I watched in amazement as he upgraded from twin LMS-Ultra 18" subwoofers ($1000 each just for the drivers) to his current DIY arrangement, an 18,000-watt beast with sixteen 18" drivers. That amount of power and displacement is on par with what one finds in a medium-sized digital IMAX auditorium. Austin posted an excellent build thread, which is well worth a look Once I saw pictures of popalock's system, I realized it was something I had to experience in person. Putting that much power into such a small space results in a completely different level of bass pressure, as anyone who has ever been into car audio—and especially SPL competitions—can attest.One of the many aspects of DIY subwoofer building that I find fascinating is the large selection of design and configuration options . Dipole, infinite baffle, ported, T-line, sealed, horns, dual-opposed—there are so many subwoofer types to choose from. Austin decided pursue maximum displacement in the least amount of space. He chose the most direct route: employing multiple sealed subs, and feeding them a lot of power.When I recently approached Austin about demoing his system, he mentioned that he was about to have a new screen installed by Rich, aka snickers1 on AVS . Rich is the owner of falconscreens.com , a company specializing in high quality—yet affordably priced—acoustically transparent screens. Austin suggested that I coordinate my visit with the installation of his new screen. We made the arrangements, and on Saturday, July 13, I had my opportunity to experience some of the most intense bass reproduction I have ever heard and/or felt. Adding to the fun, AVS members pauleyc and NathanJ were on hand to help with the install and witness the demo.With that much power on tap and that much driver displacement, it becomes possible to reproduce frequencies that are outside the musical and audible spectrum, and to do so at tremendous volume levels. These ultra-low sound waves—called infrasound—are technically inaudible, but easily felt. In modern movies, the LFE track sometimes utilizes infrasound, usually to excite—or scare—the audience. Once the movie demo got rolling, it became clear what a unique experience it is to hear and feel so much audio power in such a small space.I want to take a moment to discuss the actual subwoofers, since they were the star of the show. The drivers came from an independent distributor called Stereo Integrity . Enthusiasts on the AVS DIY Speakers and Subs forum tout the 18-inchers popalock used for their great price/performance ratio. At $190 per unit, the Stereo Integrity HT 18" driver is relatively affordable for such a large and powerful driver—and the design is claimed to be specifically tailored for home-theater applications. Bass management was handled by a MiniDSP 10x10HD The goal of the extreme-bass lovers in the DIY forum often includes achieving beyond reference-level bass, all the way down to single-digit hertz. Austin's system has that capacity, and as a result, the demo was an eye (and ear) opening experience.Before discussing the demo, I want to mention the screen installation I witnessed during my visit. I timed my arrival to coincide with the installation of a new 16:9, acoustically transparent screen, the Falcon Vision HD. From unpack to hanging, the entire process took about half an hour, minus a few brief breaks to take pictures of the process. I was impressed with the quality of the frame—I had a chance to give it a good shake; it felt like a single, rigid, and solid piece of thick aluminum. The black velvet was in perfect condition—not a spot of velvet "crush." The fabric screen unrolled and stretched onto the frame with ease, and before I knew it, we were in the theater, hanging and centering the new screen on the wall.The screen is acoustically transparent fabric with a gain of 1.1, but popalock's theater was not ready to install the center speaker behind the screen. We decided to demo the new screen with a phantom center channel instead. Prior to the demo, we spent a few minutes scrutinizing the weave in the fabric, concluding that from any distance six feet back or farther, it was impossible to see the fabric's weave. The main viewing position was ten feet back—from a ten-foot-wide screen—so the perforation and weave was invisible.The screen itself looked great—the size was an upgrade for Austin—the material really made colors "pop," and everything was nice and sharp. The Panasonic PT-AE7000U projector proved up to the task of filling the screen with sharp, colorful, contrasty images. Nathan noted there was no hint of moiré, which we all agreed with. A demo of a scene from Avatar displayed all the sharpness and saturation I would hope to see from a Blu-ray. It is the first time I have watched an extended cinematic-quality clip from Avatar in 2D (as opposed to 3D), and it looked great.Powered directly by a Pioneer Elite SC-57 AVR , the 4.1 configuration had dynamic range to spare and pulled off visceral displays of raw power—crucial when so much bass power is on tap. It is a good thing Klipsch makes relatively efficient speakers; the SC-57 is a stout receiver, but some of the peak levels we achieved that evening were off the chart. The main front speakers—a pair of Klipsch RF-7 IIs —played the part of monstrous satellites, crossed over at 80Hz despite nothing about them being "small," while a pair of Klipsch RS-62s handled the surround sound duties with aplomb.Two clips in the demo really stood out in terms of bass—a legendary pulse of ultra-low energy during a scene in Black Hawk Down that fans refer to by the key line: "f***ing Irene!" The resulting bass pulse emulates the effect of standing under the blades of a Blackhawk helicopter preparing for takeoff. I gathered that Austin has actually experienced this in real life, while most people have not. I've flown in a few helicopters myself (although not in a Blackhawk), and I can vouch that the feeling of being near those spinning blades was tangible—the thump was accurately reproduced by Austin's system. When combined with the new screen, which filled one's vision, the effect was more than immersive, it was like a simulation.Watching the demo, from left to right: NathanJ, snickers1, popalock, and PauleyCWhereas the Irene scene was a very specific emulation—standing under the blades of a chopper—the crash scene from " Flight of the Phoenix " was a considerably more complex example of how massive amounts of bass can alter the viewer's experience. This was the piece-de-resistance, one of the truly great subwoofer demos—ever. Thuds, creaks, churns, and explosions felt utterly real. My eyes were suddenly diverted from the screen by the spectacle of eight 18" subwoofers moving in unison, with over an inch of total excursion; the cones looked as if they were going to pop right out of those boxes. Eyes back to the screen, and a huge groaning shudder took over everything—if not for the total suspension of disbelief this created, I might have noticed that the 100-pound Klipsch RF-7 IIs were hopping around, that the house itself was shuddering as if in an earthquake. In effect, Austin's 18,000-watt subwoofer system brought the disaster scene to life, made it tangible.We watched a few more clips—the ease with which the system handles the booms and bangs of modern movies is sublime—but those two scenes really left an impression. Due to the length of my ride home—Austin is in the D.C. area, and I live in Philly—I had to depart sooner than I would have preferred. It would have been nice to enjoy a full movie on that uniquely capable, gloriously powerful system. Nathan agreed, calling it "pure bass indulgence."The next day, I asked Rich about his impressions in an AVS private message. His response: "I may not be someone that is very well versed in the world of insane bass, but I must say after hearing/feeling Austin's impressive setup, I realized that my theater is missing something. Austin started his demo with that scene from Black Hawk Down, and I felt so out place when everyone else kept chanting "Irene...Irene," all I could say when the helicopter fired up was WOW!That is exactly how I felt as well, and I believe it is how everyone else who witnessed the demo felt: Genuinely wowed. Bravo, popalock!