|• Audyssey DSP room/ subwoofer equalization
• Supplied Windows PC setup software (XP or Vista-32), cables, and calibration mike
•Connections: Line inputs for mono or stereo subwoofer signal; outputs for one or two subwoofers; USB computer interface; mike input
• Dimensions + Weight 17 x 9 x 2 in; 61∕2 lb
Room acoustics have been vexing sound reproduction ever since the owner of the first Victrola dropped its cactus needle onto the first record. Sonic reflections, in particular the low-frequency "standing waves" that build up into zones of high and low pressure - i.e., stronger or weaker bass - often influence what we ultimately hear far more than any niceties of speaker or amplifier design.
Engineers have long tried to do something about the problem, but it's only in today's digital signal processing (DSP) age that the issue is really beginning to be addressed. DSP can manipulate audio signals in both amplitude and time domains, something that's impractical by analog means. The proof of this pudding is baked into the sophisticated DSP algorithms from companies like Audyssey Labs, Trinnov (France), and proprietary makers including Pioneer and Yamaha, which endow even modestly priced A/V receivers with auto-setup calibrations, roomcorrection systems, and more.
A more specialized example has arrived from an unexpected source: SVSound, the Midwest speaker maker whose cost-effective subwoofer and sub-sat designs have won favorable attention in these pages and elsewhere. SVS now offers a freestanding, bass-centric helping of Audyssey's MultEQ DSP via its new AS-EQ1, a hardware/software package for auto-setup subwoofer-level and distance calibration, and subwoofer-room integration/correction.
SVS's box embodies a superset of the MultEQ algorithms found in several A/V receivers, with the company claiming twice the filter resolution, more processing power, and the ability to integrate more setup-mike positions. According to Audyssey, MultEQ goes beyond simple "spatial averaging" to deliver improved sound from multiple seating positions. (A classic foible of conventional EQ is that cutting a frequency to improve response at one seat almost invariably induces a response that is less accurate at another location.)
SVS's unprepossessing EQ1 hardware is a low, almost featureless single-space rack-mount box that connects between a receiver or preamp-processor's subwoofer output(s) and one or two subwoofers; a clever magnetic front panel pulls off to reveal a mike input jack and USB port. You also get an outboard power supply, a standard Audyssey microphone for use at setup time, and a long USB cable to connect the EQ1 to your PC, plus rack ears, a nice single-RCA subwoofer cable, stick-on feet, and so on. Oh, yeah: You need a Windows PC to run the proprietary Audyssey SubEQ software (XP or Vista-32) and to display or print the PDF manual found on the included CD.
The AS-EQ1's back panel offers up dual subwoofer inputs and outputs. Both outs can be independently configured for systems incorporating multiple subs. An extra RCA monitor out is provided for precise level-matching of the main and sub channels.
I ran SubEQ on an aged Dell P4 under XP Pro with no problems, doing the self-install from the SVS CD and following the prompts. The straightforward routine includes the ability to integrate two identical or different model subs, compensating for different woofer locations, sensitivities, and responses - a huge boon, as anyone who has ever spent hours optimizing multiple subs by ear will know. So, integrate two subs is what I did, employing my own excellent sealed 12-inch in its usual position, with a second, vented 12-incher situated along the opposite wall.
The EQ1 setup/calibration routine is very much like the Audyssey MultEQ feature on a receiver or preamp, except that you run it from a PC screen instead of a receiver's onscreen display. The PC communicates with the SVS box via the USB link. Setup is self-prompting and should present no problems as long as you follow the instructions and commentary that appear in a sidebar. (SVS's 34-page Operator Manual PDF includes the same information, plus a good deal more.)
With the supplied mike at the initial, primary listening position, you click the "Measure" icon on the PC and the EQ1 induces a quick series of bleeps. After a brief pause for processing, the software prompts you to move the mike to the next position. (You can measure as many as 32 of them.) SVS suggests two measurements for each anticipated listening location, one at seated ear height and a second a bit lower. In practice, the more positions - all within the general listening zone and away from walls - the merrier, to give Audyssey's algorithms more data to crunch for a closer assessment of your room's important acoustical quirks.
All of this is not very different from the Audyssey MultEQ found in numerous A/V receivers - though 32 is nearly three times the normal amount of mike positions, and, as mentioned, SVS claims double the resolution. But the EQ1 incorporates a few important details. First, the SVS software prompts you to coordinate setup with any speaker/room-EQ processing, Audyssey or otherwise, that might already be active in your receiver or preamp, leaving the EQ1 to manage just the lower octaves. Second, a preflight routine calibrates the EQ1 with your system's balance and helps you set the sub's (or subs') own level control(s) to the correct point. Finally, the setup program walks multisub installers through options that calibrate two subs to function as a single entity (which is what I did), or to create a two-in/two-out setup for "stereo bass." (Some of us consider "stereo bass" an oxymoron, since the wavelengths involved are many times the dimension between the ears of even us true melon-heads, but I ain't scaling that slippery slope here!)
Once your setup and calibration is complete, the SVS software displays a "Calibration Certificate" showing before and after curves (presumably but not explicitly for the first listening position) and prompts you to permanently upload the data from your PC to the EQ1. This can be superseded by a subsequent run, but there's no onboard memory for multiple data sets. At this point you can shut down the PC, put away the long USB cable and microphone, replace the Subwoofer Equalizer's plain magnetic front panel, and effectively forget that the EQ1 is even there.
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