If One Sub is Good, Are Two Better?
PLUS a few more Subwoofer tips.
Author: Alan Lofft, Axiom Audio
My colleagues and friends who have large vaulted-ceiling rooms all run dual subs. Taste plays a role as well. If you like your music or soundtracks really loud and deep, go for two subs. If you have a huge room and you want really loud sound and deep bass, then look at physically larger subwoofers with bigger amplifiers.
If your room has typical dimensions--20 x 14 x 8 ft., about 2,100 cu. ft.--one well-designed subwoofer with an internal amplifier equal in size to the full output of your receiver (full power for 1 channel + 1/8 power x the number of other channels) and a 10-inch or 12-inch driver should deliver solid deep bass extension and ample output for music and movie soundtracks. On the other hand, if the room is larger than usual (4,000 to 8,000 cu. ft. or bigger) or has a vaulted or cathedral ceiling, you should definitely consider running an extra subwoofer.
Big rooms, especially the "great rooms" so common in many suburban homes, really devour deep bass, so two subs will generate enough sound pressure to fill the place. They'll also give you smoother distribution of extended bass over several different listening locations. My colleagues and friends who have large vaulted-ceiling rooms all run dual subs. Taste plays a role as well. If you like your music or soundtracks really loud and deep, go for two subs. If you have a huge room and you want really loud sound and deep bass, then look at physically larger subwoofers with bigger amplifiers, like the Epicenter EP600.
There is no specific need for two subwoofers to be identical in terms of brand name or physical size, but don't use a small, cheap sub with a large, good one. As to setup, try the subwoofers in opposite corners (diagonally) of the room, one in the front and one at the back, with an initial crossover setting of 80 Hz and the rear sub phase switch on 180. If the subs are too boomy in the corners, move them away from the corners along one wall or the other until you get smooth coverage of deep bass from the main seating areas in the room.
Another recommended placement for dual subwoofers is on opposite end walls in the middle of each wall, or on opposite side walls in the middle of each wall.
There is no magic formula for subwoofer placement: experiment with locations, because every room is different. But be on the lookout for "nodes," which are areas in the room where there will be way too much bass, and other areas where you will hear little or none. The idea is to tame these nodes so you get uniform output in most of your important locations. If you have a choice, square rooms are the worst for nodes; irregular or rectangular shapes are preferable, and as you move couches or chairs closer to walls, bass intensity will increase. Conversely, the middle of the room will have less bass intensity.
How to Find the Best Place for Your Subwoofer
Want to crawl around on your hands and knees like our four-footed friends? It may strike you as a bit odd to do this in the pursuit of smooth, deep, and even bass, but it’s really the best technique to find the ideal spot for your EP125, EP175, or EP350 subwoofer, or Epicenter 500 or 600 Intelligent DSP Subwoofer. (Still, I wouldn’t advise doing it within sight of family or friends.) For that matter, this low-profile approach works for any subwoofer. And you’ll only have to heft your subwoofer twice.
Move your subwoofer as close as you can to where you sit. If it’s a chair, move the chair aside and place the sub where the chair was. If it’s a couch, slide the couch temporarily out of the way and put the sub about where you usually sit.
Play a DVD with lots of low-frequency effects or a CD with plenty of deep bass, the kind that really kicks your sub into motion.
Now the action. Get out the kneepads and crawl about the room in the general area where you were thinking of locating the sub. Go several yards in each direction--near the wall, out from the wall, towards a corner, away from the corner, and so on--while you listen for smooth and extended bass response.
At some locations, the bass may seem really exaggerated and boomy. In other spots, it may almost disappear. Pick a location somewhere between these extremes. That’s it! Mark the spot (no, not like a dog or a wolf would!), then move the subwoofer into that position. Now put the furniture back.
Test the technique by playing the same deep bass selections, only this time sit in your favorite chair (where the subwoofer was). The deep bass should sound just like it did at the place where the sub now sits.
You see? It works. And I hope you noted any dust bunnies while you were at it.
How to optimize subwoofer levels
It's confusing. In most home-theatre setups, your Dolby Digital/dts A/V Receiver has a menu for setting the levels of all your speakers, including an adjustment for the Low Frequency Effects (LFE) channel. This determines the strength of the electrical signal fed to your subwoofer's built-in amplifier. But there's also a volume control on your subwoofer, right?
So where do you set each control?
To keep your receiver's LFE output level from overloading the input stage of your subwoofer amplifier, and to keep noise levels below audibility, adjust the receiver's LFE/subwoofer output level to "0 dB", and leave it there. When you do your level checks, start with the sub's volume control at about the 10:00 a.m position, then use that control to set or trim your final subwoofer level. And of course you may have to vary it somewhat depending on which source you're watching or listening to--CD, DVD, VCR, or off-air TV. However, except for some bass-heavy CD or DVD programming, the sub level shouldn't require much re-adjustment.
Alan Lofft was, for 13 years, Editor in Chief of Sound & Vision, Canada's largest and most respected audio/video magazine. He edited Sound & Vision (Canada) until 1996, when he moved from Toronto to New York to become Senior Editor at Audio magazine.
Lofft has been writing about hi-fi and video professionally for over 20 years, ever since his first syndicated newspaper column, "Sound Advice", began appearing weekly in The Toronto Star, Canada's largest-circulation daily newspaper. In the late 1970s, he became a contributing editor, columnist, and equipment reviewer at AudioScene Canada, the leading national consumer electronics magazine at the time.
He also wrote on consumer electronics for Maclean's magazine and made occasional appearances on TV on "Canada AM," the national CTV morning show, and on June Callwood's national afternoon TV talk show.
In 1983, he was appointed editor of Sound Canada magazine, which he relaunched in 1985 as Sound & Vision, incorporating video content and reviews as well as hi-fi and audio features. He also became a contributing editor to Stereo Review in New York, and an audio columnist for Music Express, a Canadian rock magazine.
An audio and electronics enthusiast from childhood, Alan began building vacuum-tube hi-fi gear for his father, who was an audiophile in the 1950s. Lofft's passion for audio continued through college, during which time he hosted and produced "On Campus", a radio show taped on location (on a portable Ampex 650 open-reel recorder) at Wilfrid Laurier University and broadcast locally in Kitchener, Ontario.
After graduation, he entered TV journalism, joining CBC television in Toronto as a production assistant and story editor for "The Day It Is," TBA", and "The Way It Is", daily and network public-affairs TV shows produced by the late Ross McLean. He continued to work in broadcast journalism until the mid-1970s, including a period as a reporter on an evening news-hour show at CITY-TV, an innovative local Toronto TV station. Lofft moved from broadcast to print journalism with the publication of his "Sound Advice" column by The Toronto Star.
From a musically talented family (both his parents played violin and piano), Alan spent a period of time as a professional singer and musical theater performer on Canadian and American stages. He played the title role in the US National company of "You're a Good Man, Charlie Brown" and, in Canada, in the Charlottetown Festival production of the musical "Turvey", where Lofft also played the title role. He continues to live in New York city but maintains a solid connection to Canada with family in Toronto and a summer home on an island in Georgian Bay.