How flat is flat

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  • 08-26-2005, 08:24 AM
    swgiust
    How flat is flat
    I have been spending some quality time with my new subwoofer. Using the Avia test disk and the Infinity Rabos test disk, I am trying to get it dialed in perfect. My question is how
    flat is flat? Obviously if the sub ran the exact db at all frequencies it would be perfect. But
    that never happens in reality. Is 2 db off ok, 5, 10? What would you consider good enough?
  • 08-26-2005, 09:47 AM
    Sir Terrence the Terrible
    Quote:

    Originally Posted by swgiust
    I have been spending some quality time with my new subwoofer. Using the Avia test disk and the Infinity Rabos test disk, I am trying to get it dialed in perfect. My question is how
    flat is flat? Obviously if the sub ran the exact db at all frequencies it would be perfect. But
    that never happens in reality. Is 2 db off ok, 5, 10? What would you consider good enough?

    2db is okay, it will never be ruler flat. My subs are -+1.5db from 80-20hz, and it is much better than the -+6db I had before eq.
  • 08-26-2005, 10:59 AM
    Woochifer
    With the normal room acoustical effects, you'll likely have at least a couple of frequencies with a very large inaccuracy. In my room, I had two peaks of 10 db+ and some smaller anomalies. Depending on your room acoustics, "good enough" might simply mean eliminating the one or two biggest peaks that can create a boomy sounding bass. If you own an Infinity RABOS sub, it includes one parametric filter for doing exactly that -- identifying the most problematic frequency peak and making the correction to that frequency.

    Peaks of 20 db or more are common in typical small-medium sized rooms, and those types of peaks dominate what the listener hears -- drowning out the rest of the bass range and making the bass sound boomy with some sound and anemic with other lows.

    If you want to knock yourself out, you can use an outboard parametric equalizer with additional filters to tweak with the smaller room-induced peaks. On my system I use a Behringer Feedback Destroyer, which has 12 parametric filters per channel. My room correction used a total of 9 filters, which brings my sub to within 2 db all the way down to 25 Hz, but that was probably overkill since some of the adjustments were less than 3 db. The sub in my room would still sound fine with as few as three adjustments.