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Low qts speaker in a sealed cabinet?

Discussion in 'Amps and Cabs [BG]' started by K Dubbs, Jul 17, 2003.

  1. Jul 17, 2003 #1
    K Dubbs

    K Dubbs Just graduated from OSU, Go Bucks!

    Mar 16, 2002
    Toledo, Ohio
    As a general rule, I know that high qts woofers (.40+) should be used in a closed/sealed design. What happens to a woofer with a qts of say... .33? Sure the bass output will be lower, but does the sealed design affect the mid, upper mid, and high areas?
     
  2. Jul 17, 2003 #2
    ThunderStik

    ThunderStik Guest

    Jun 25, 2001
    Claremore OK.
    I would think that the mids and highs would also be affected but only somewhat. As the air in the box would add to stiffness of the suspension, so I suspect the entire frequency band would be affected but much greater on the low end (80-100hz and down). But this is speculation.
     
  3. Jul 17, 2003 #3
    bgavin

    bgavin

    May 3, 2001
    Orangevale, CA 95662
    The Efficiency Bandwidth Product (EBP) is a more accurate method of determing sealed vs vented cabinets. An EBP <= 50 is sealed, and >= 100 is vented. An EBP of 75 is midway, and will work in either sealed or vented boxes. Several of the Eminence Beta and Delta drivers have a Qts > 0.37 and an EBP of 100 or more.

    Sealed boxes are about -3dB less efficient in the low end that a vented box. Cone excursion continues to increase in sealed boxes, where vented box cone excursion is almost nil at the tuning frequency.

    The smaller sealed boxes are more resistant to cone movement than are the larger sealed boxes. As the box volume decreases, the Qtc increases, as does the power handling. It is my understanding the power handling increase is a consequence of less cone excursion, and is limited by the maximum input power rating of the voice coil before it melts.

    Larger sealed boxes have more cone excursion, tighter transients, and a higher rolloff point. The two basic sealed alignments are the B2 and D2 types. B2 is smaller, has the lowest F3. The D2 is larger, rolls off a bit higher, but at a more gentle slope, and has better transient response.