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DIY compact cabs

Discussion in 'Amps and Cabs [BG]' started by David McCannon, Sep 10, 2003.


  1. David McCannon

    David McCannon

    Jan 24, 2003
    I'm a DIYer and have been pondering a compact 1X12
    using the Eminence Kappa Pro 12, specs:
    Usable freq range - 35hz-2.5khz
    Recom. enclosure vol. - .6 to .8 cu.ft. vented

    This driver seems to be designed for this type of
    enclosure. I was wondering how a tuned frequency
    is determined for the design. It seems impossible to port a cabinet that small with a freq. to help
    the low end (I play 5 string bass and low B is approx. 30hz) so how do designers decide what freq
    to tune the box to for small compact enclosures?
    I know the Compact 12 Avatar used to make had 2 4" ports 1" deep which would be a very high tuned freq. Any help is appreciated.

    Thanks,
    David
     
  2. jdombrow

    jdombrow Supporting Member

    Jan 16, 2002
    Colorado Springs, CO
    David,

    Post these questions at "AudioAsylum.com" in either the "Speakers" or "Pro Audio" forums. There are lots of knowledgable people there who can help with this.

    JD
     
  3. This is an arbitrary thing: what is it you want to achieve with the cab? Do you need the fundamental of you low B reproduced? Then you probably need a different driver, and possibly a larger amp. Subwoofers tend to be power hogs. If you want to build a small, loud enclosure you probably have to tune to 60-80 Hz and forget about fundamentals altogether. Most bass guitar cabs are designed that way (loud, small).

    There are quite a few knowledgable people around this site, so keep asking those good questions.
     
  4. ESP-LTD

    ESP-LTD

    Sep 9, 2001
    Idaho
    -what Joris said.

    You need to decide how you want to manage low vs loud.

    The Kappa Pro 12 is a very nice speaker for mids and highs, but if you do a search here, you'll discover it runs out of steam down low as it exceeds excurion limits (small Xmax).

    I have the Avatar B112 (crossed over at 150hz) and agree with your assessment of the tuning. However, if you biamp the B112 and run 2x that power into a 2 ohm load of 12" car audio subs tuned to 30hz, it all sounds fine.

    There are no secrets- you can have low or loud, but to get both you will need a truck to carry it and a lot of power amp.
     
  5. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    As a learning exercise, can I suggest you download WinISD. It's a free cab designing program that contains a large database of speakers, including most of the Eminence drivers.

    Get WinISD to spit out a suggested box size and porting. This will give you somewhere to start. Then manually override all it's suggestions one by one and watch the graphs change. You can learn a lot about the effect of changing the tuning and size and what effect it has on the overall sound.

    By the way, the "usable frequency range" is one of those stats that can be cooked so many different ways, it's chicken one day and beef the next. It's one thing to say it will work down to 35 Hz, but it's not good to anyone if it's down 12dB at that frequency, or is it down 3dB? Your guess is as good as mine.
     
  6. Download my spread sheet. Sort it by Manufacturer, then Diameter, and finally by Model.
    This will put all the Eminence 12" drivers close together on the screen.

    You then compare the Kappa Pro 12 with the others, and come to the conclusion the Omega Pro 12 is a little bit better driver with a lower F3. Both will produce the same maximum SPL before Xmax limitations occur. The Kappa Pro is good to 2,500 Hz, where the Omega Pro rolls off at 1,200 Hz.

    When you are ready to buy, email me and I will give you the name of an authorized Eminence dealer who drop-ships product for less cost than Parts Express.