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Need advice re: enclose crossover

Discussion in 'Amps and Cabs [BG]' started by membluz, Sep 7, 2008.

  1. membluz


    Sep 3, 2001
    Winnipeg Canada
    I'm building a cabinet (using the Eminence Disigner software) with an Eminence CB15 (8-Ohm 300W 48Hz-3KHz) and an Eminence Alpha 8MR (8 Ohm 125W 400Hz-4.8KHz).

    Each speaker will be mounted in its own 'compartment' in the enclosure.

    I'll be powering this enclosure with an Acoustic Image Focus 2R Series III amplifier and using it for my upright bass and my Fender Precision bass.

    I plan to connect them in parallel for a 4 Ohm enclosure. Do I need a crossover or some other electronic component to prevent the low frequencies below 400HZ from having a negative impact on the Alpha 8MR speaker?

    Thank you.
  2. Sorry, things don't work that way. The woofer and mid should be connected to a crossover. The impedance will be 8Ω. The mid is, IIRC, a sealed back unit so it does not need a separate compartment. Eminence make suitable crossovers that you'll get from the same supplier as the speakers.

  3. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    There will be negative impact, a toasted mid-driver, and instantly so. :crying:
    Study this:
    Also reconsider the crossover frequency. 400 Hz is too low.
  4. spode master

    spode master

    Jan 21, 2007
    Did your Eminence software come with the X-over design software???

    The Eminence Software is actually Harris Tech Bass Box Pro. Normally Xover Pro comes with it.

    I use it often.

    You can design a reasonable Xover with that software, that will be much bettern than any off the Shelf Xover.

    (Off the Shelves really only work well for specific driver combinations, some of the electro and acoustcal interactions are far more complex than a generic Xover can compesate for.)

    Good luck, I may be able to help you with an Xover schematic if you need!

  5. membluz


    Sep 3, 2001
    Winnipeg Canada
    Thank you for your responses and suggestions.

    Spode Master - Yes - I definitely appreciate your offer to help with a schematic.

    Bassman Paul - Would the Eminence px2-1k6 work in this application? The specs are:

    2-Way crossover
    Cabinet Ready
    Crossover Frequency 1.6kHz
    Slope – Low Frequency 12dB/octave Butterworth
    Slope – High Frequency 18dB/octave Butterworth
    Impedance 8 ohms
    Power Handling 400 Watts RMS
    High Frequency Level +/- 9dB

    Billfitzmaurice - what do you suggest for a crossover frequency?

    Thanks again everyone.

    Tony jazzplayer@mts.net
  6. spode master

    spode master

    Jan 21, 2007
    Spent a little time futzing around. Don't know what volume you went for. I used the computer Optimized Vented Volume for the 15.

    The HT version of Bass Box Pro doesn't have the Alpha 8MRA, so I had to manually enter the TS parameters.

    Don't know what the actual volume of the sealed basket is, but it seems like high Q is unavoidable with this driver, I just took HT's suggestion for a sealed box.

    Here are the results I have for the two drivers X-ed over at 800Hz (not where I'd want to cross the 15 but seems like it gets decent xover response here).

    The Xover for the Woofer is a 12dB L-R, the Xover for the Mid is 24dB L-R




  7. subsdcribe
  8. spode master

    spode master

    Jan 21, 2007
    "I think it burnt me finger"

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