Why a woofer?

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  • 12-01-2003, 12:08 PM
    Miket99
    Why a woofer?
    30 years ago when I was much more of an audiofile I would have know the answer to this question: Ok I get more bass from a Subwoofer other than that why would I consder adding one to my system?
  • 12-01-2003, 01:04 PM
    Pat D
    Well, the best place for the main speakers is where they image the best. This is seldom the best place for the most even bass response. So, with a subwoofer, you can put the sub where it performs best (usually near a corner in most rectangular rooms) and at least 6 feet from a door or other large opening, and you can put the main speakers where they perform best, usually away from the walls and corners (unless specifically designed for such locations as with some Klipsch and Allison models).

    A good subwoofer will have not only deeper bass but be capable of more output in the deep bass than most speakers. Corner placement is like horn loading as it restricts radiation into the room to 1/8 sphere, so the sub doesn't have to work as hard to produce any given level. This will require turning down the volume control on it. As well, the sub usually has the flattest and deepest response near a corner. If the sub is crossed over below 80 Hz or so with a steepish crossover, it should be sonically invisible.
  • 12-01-2003, 01:19 PM
    TinHere
    Quote:

    Originally Posted by Miket99
    30 years ago when I was much more of an audiofile I would have know the answer to this question: Ok I get more bass from a Subwoofer other than that why would I consder adding one to my system?

    Also, setting your speakers to small and using a sub will cause less stress on the amp, and allow the speakers to "concentrate" on the mids and highs while the sub handles the low end.
  • 12-02-2003, 07:24 AM
    the hand of boredom
    Quote:

    Originally Posted by Pat D
    As well, the sub usually has the flattest and deepest response near a corner.

    Is this true, Pat? I've been under the impression that corner placement will give the perception of increased output, and that placement in the middle of the room (usually) will render the most accurate bass response (ie, flat and deep).

    Or maybe its just too early in the morning for me to think. Where's my damn Red Bull?

    THOB
  • 12-02-2003, 07:29 AM
    the hand of boredom
    TinHere:

    I have the X30 crossover between the pre-amp stage and the amp stage utilising the 50Hz filter. This should give me the full-bodied vocals still from the mains, correct? Where would you suggest I start tweaking to set the high-pass(?) for the subwoofers' frequency?

    I don't have the SPL reader of Bass Test CD yet, and always find it difficult to get that seamless integration of the sub-bass systems to the mains.

    THOB
  • 12-02-2003, 09:37 AM
    TinHere
    Quote:

    Originally Posted by the hand of boredom
    TinHere:

    I have the X30 crossover between the pre-amp stage and the amp stage utilising the 50Hz filter. This should give me the full-bodied vocals still from the mains, correct? Where would you suggest I start tweaking to set the high-pass(?) for the subwoofers' frequency?

    I don't have the SPL reader of Bass Test CD yet, and always find it difficult to get that seamless integration of the sub-bass systems to the mains.

    THOB

    Hey THOB,

    Wish I could help you but when it gets deeper than generalities, helping with newbie set-up poroblems [it's usually setting the DVD to bitstream in the set-up menu], parroting what people who know more than me say, or where to get good value, then it's time to hope that someone like Mr. Greene or Mr. Hertz shows up. Sorry I can't be more helpful. :o
  • 12-03-2003, 10:50 AM
    Pat D
    Yep!
    Quote:

    Originally Posted by the hand of boredom
    Is this true, Pat? I've been under the impression that corner placement will give the perception of increased output, and that placement in the middle of the room (usually) will render the most accurate bass response (ie, flat and deep).

    Or maybe its just too early in the morning for me to think. Where's my damn Red Bull?

    THOB

    Even when I knew better, I resisted putting the sub in a corner, but after trying different locations,I ended up putting it in a rear corner (you can't put that big box behind a dipole speaker as it upsets the stereo image).

    Tom Nousaine, "Subwoofer Secrets," Stereo Review, January 1995, did measurements and listening tests in 7 different room and his conclusion was that the best location was usually in a corner. In one room with a sloping ceiling the response was best with the sub moved 2.5 feet out from the corner. He also concluded that a single subwoofer usually outperforms two separate subwoofers in different places (such as opposite corners), although they can profitably be placed one on top of the other in a corner. For frequencies below the fundamental resonance of the room, it doesn't much matter where you put the sub

    Placing the sub near the listening position (say using as a footrest) is not a bad location, but you lose the reinforcement of a corner location.

    The sub should not be placed in or near a room opening such as a door or hallway.

    David J. Weinberg and Howard C. Ferstler, "Bass Versus Space," Audio, July/August 1999, came to much the same conclusions.

    The last I knew, you could submit a description of your room on the Hsu web site and they would Email you the best place to put the sub, which in my case was indeed the corner. You could also ask Tom Vodhanel of SVS, though he must be very busy.

    Putting the sub near a corner essentially horn loads it, as instead of radiating into a half sphere it radiates into 1/8 sphere, so the increased levels at your listening position are not just perceptions. So in a corner, the sub requires less gain to a chieve any given level.

    Opinions on a subject may abound, but in this case, some people have put the theories to the test and done the measurements, as well as doing listening tests.
  • 12-03-2003, 11:44 AM
    the hand of boredom
    Patty Day:

    You are starting to sound alot like Doctor Greene. Lots of good subwoofer information.

    I wish that I could stack these frickin' Servos. Unfortunately, doing that would seriously impede the view out the living space window, and would also compromise the esthetics of the room. I'm also very concerned about preserving the finish of the veneer.

    Believe me, if I had a dedicated listening room, I would give it a shot; take the several weeks to find the right balance of crossover and gain.

    Right now I have the subs' drivers about 4 ft from the front wall, about 9 ft apart. I had the xover set previously to 55Hz with the mains (Studio/40) cut off at 50Hz. I now have the xover around 70Hz and I know now what I was missing. Everything has more impact; better 'grunt'.

    I know that there is a terrible peak in the higher bass region, around 90Hz which muddies up the detail of the midrange quite a bit. There are probably some nulls in the frequency range, but those are a bit harder to detect, aren't they? For now, the sound is incredible (with the exception of that annoying peak) and it's scary to know that it can be better with the addition of all the tools: SPL reader, calibration disc, traps, and EQ.

    If you could only have one, would you choose the EQ or the bass traps?

    Cheers, Pat.

    THOB