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Will a sub-cab work?

Discussion in 'Amps and Cabs [BG]' started by Dean_CustomJazz, Jun 20, 2002.


  1. Dean_CustomJazz

    Dean_CustomJazz Guest

    Jan 23, 2002
    woburn
    I have a hartke ha3500 and an swr goliasth jr. I can add another 8 ohm cab, and i found 1x18 downfiring sub. I was thinking on getting the sub because it has a crossover in it. The 2x10 will produce highs and lows, and the sub will take all the lows. Is this a good idea?
     
  2. VicDamone

    VicDamone

    Jun 25, 2000
    Generaly a subwoofer uses alot of watts compaired to a full range system. Even though both cabinets are rated at 8 ohms, the disparity in their power requirments may give an unbalanced sound. The sub may not have very much output. Try before you buy.

    If you had a second power source the sub would be much happier.
     
  3. Dean_CustomJazz

    Dean_CustomJazz Guest

    Jan 23, 2002
    woburn
    well i aint going to send any my cabs to summer camp/i will keep looking
     
  4. Unless you're bi amping out of your head, I'd pass on the crossover in the cab. I've found that if you're running full range, the ONLY speaker size I'd use is a 10" speaker. Unless you bi amp, the variable that matters most in the cab is speaker mass, and you get more mass with a 4x10 than with two 15" speakers.
     
  5. The important part is the amount of air displaced by the driver. This is the cone piston area (Sd) multiplied by the cone excursion (Xmax). Cone movement increases 4x for every octave lower, at the same loudness level. If the cone has little Xmax, it won't produce much low bass.

    A typical Eminence 15" driver has 2.48x more piston area than a comparable 10" model. Doing the math, a pair of 15" drivers has the same piston area as (5) 10" drivers. Roughly, this same ratio applies to the driver volume displacement for these drivers. The 15" will go down lower, but the 10" are typically more punchy.

    As for bi-amping, IMO the only way to do it right is with an active crossover such as the Rane MX22 and a stereo power amp. As pointed out above, a volume mismatch between highs and lows will make the rig sound just awful. The MX22 allows a wide range of crossover points and independent volume control of each channel. It is independent of driver impedance or mis-matched impedances such as 8 ohm highs and 4 ohm lows.

    A passive crossover is extremely sensitive to impedance mismatches and must be designed exactly for the drivers it controls. At this low frequency, the passive crossover will be massive, and expensive. It will cost as much as a used Rane MX22 on eBay, and a passive crossover won't perform anywhere close to the Rane.