Stereo EQ's for Subs?

Discussion in 'Archived Threads 2001-2004' started by Jeremy_Friedman, May 30, 2001.

  1. Jeremy_Friedman

    Jeremy_Friedman Auditioning

    Sep 14, 2000
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    I've got two Shiva subs placed in the front corners of my room. I presume I'm getting some nasty peaks/dips at various frequencies, but I haven't gotten a Radio Shack SPL Meter yet.
    Anyhow, if I decide to EQ my subs, is it best to do it as a "system," with one EQ, or EQ each sub individually, therefore shelling out more cash?
    -Thoughts are welcome-
    Jeremy C. Friedman
  2. Greg Monfort

    Greg Monfort Supporting Actor

    May 30, 2000
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    No two corners of any typical room I've measured yielded ~ the same FR, so 'stereo' subs need 'stereo' EQ IMO.
    Loud is beautiful, if it's clean
  3. Wayne A. Pflughaupt

    Aug 5, 1999
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    Katy, TX
    Real Name:
    Welcome to the Forum, Jeremy!
    Any subwoofer needs to be EQ’d. I’ve had four in my system at different times, and all sounded 100% better after equalization.
    You might want to rethink putting dual subs in two different locations in the same room. The following is from Howard Ferstler’s website, under articles titled “Bass and Subwoffers in a Room,” and “Speaker Sound-Room Sound.” You can see these and more great articles at
    “An interesting aspect of speaker-room behavior at low frequencies involves the really deep bass range. In spite of the different frequency range, it is directly related to the boundary-suckout phenomenon.
    “Briefly, if you employ two subwoofers, remember that a point half-way between them is going to behave acoustically like a boundary. Thus, two subs placed 12-feet apart will exhibit a null at about 56 Hz. If either or both of those woofers are also about 6 feet from a boundary, the null will be reinforced accordingly. Even subwoofers 20 feet apart will display a dip in the 33-Hz range.
    “Consequently, as speaker tester Tom Nousaine has pointed out in numerous essays, one will get the most consistent subwoofer performance if they employ a single sub, positioned in, or close to, a corner. A subwoofer positioned that way is so close to three major room boundaries that any notches it generates will be well above its crossover-controlled operating range.”
    Nousaine wrote two articles a few years ago in Audio magazine on multiple subs that indicated the best performance and smoothest frequency response is realized if multiple subs are located in the same corner (“Placing the Bass: Two Subs in a Corner Beat Five in the Round,” June 1996; “Birth of the Boom: Room Acoustics at Low Frequencies,” June 1998).
    I’ve EQ’d dual subs in two locations, and take my word for it, it is a nightmare. IT took me over 20 hours of testing, EQing, listening, re-EQing, etc. before I was happy with the results. After all that, I later determined that performance was substantially better with both subs in the same corner. Not only was performance better, but EQing was a snap.
    You definitely cannot EQ subs, in the same or separate locations, without a SPL meter and a source for test tones. The test source must have signals with at least 1/3 octave, or preferably 1/6 octave intervals. After you take readings with the meter at the different frequencies, you will be able to see where equalization needs to be applied.
    Wayne A. Pflughaupt
  4. David-alexander

    David-alexander Stunt Coordinator

    May 28, 2001
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    I've tried to get good bass response and high SPL and smoothness with two subs apart: forget it. now they are stacked, side loaded ( right wall and on the floor, no spikes) and it's perfect: loud, smooth, deep.
    use the Berhinger FBD 1100P pararemtric equalizer: the best in its league.
    but first, the right placing.

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