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Building a portable cabinet with good low end.

Discussion in 'Amps and Cabs [BG]' started by 6L6, Apr 18, 2005.

  1. 6L6


    Apr 7, 2005
    Has anyone built a easy to carry
    speaker that can handel the B string ?
    Any good DIY ideas ?
    SPL should be enough for practice
    with a band or playing in a bar.
  2. I wish you luck. The 1rst law of speaker building says you can have...

    1. Good frequency response
    2. High effeciency


    3. Small size

    You may pick any two, but you can't have all three.
  3. I agree. You may be able to come up with a good comprimise if you build a two way cab with a carefully chosen 12 and a 6 to carry the mids that would be lacking in any quality low frequency 12.
  4. msquared


    Sep 19, 2004
    Kansas City
    I am a big fan of the idea of "horribly inefficient but deep as hell", a la Acme's gear. I've been playing around with design ideas in WinISD for a few months now, and after playing with a number of different drivers, my favorite is turning out to be the 12" Dayton Titanic Mk3.

    According to WinISD, this driver in a sealed box the size of a Berg HT112 (17.5x15x13) will give you a -3db frequency of around 36Hz. Group delay when hitting a low B is around 7ms. I haven't gotten around to building one yet but if my HT112 ends up having low end issues, this is going to be the first route I take.
  5. The Clap

    The Clap

    Jan 5, 2004
    Scottsdale, AZ
    You'll find that that's futile in the end. Acme's stuff may be rated at the low end of the sensitivity spectrum, but it's still worlds louder than that sub. Pro Audio speakers are rather different than car audio/home audio speakers, and that sub will hardly make appreciable levels of sound in a room of moderate size. Speakers that go that low in that small of a box (and don't cost upwards of a thousand dollars) don't have the efficiency to be useful live.

    It's a good thing to try though, get a home audio subwoofer and see how loudly you can play your bass through it. It may sound loud, and it'll certainly sound deep, but it's not loud enough to compete with an electric guitar. In WinISD, check the maximum SPL graph; you're looking for full-power levels of 114-120db for most good live gear, see what that sub will do.
  6. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    It won't sound all that loud either. The low end (40-80 Hz) sensitivity will be roughly equal to that of a pro-sound driver, but in the second octave where most of the power demands for bass lie it will be about 10dB lower in sensitivity. To keep up with a 200 watt rated pro-sound driver it will need an input of 2000 watts, which is 1500 watts over its capacity. It seems like a good idea at first glance until you actually crunch the numbers. Then reality sets in and you realize why no one has already done it: because it won't work.
  7. Not to mention that car/home audio subs tend to have very limited hi freq capabilities. Being lazy I didn't check the Dayton spec, but some tend to start rolling off at around 300-500 hertz.
  8. msquared


    Sep 19, 2004
    Kansas City
    Yeah, I noticed the low sensitivity rating and was wondering about it, but didn't have any point of reference. I figured that for the price, if it didn't make a good live cabinet it would at least make a decent home audio cabinet. Thanks for the heads up, guys.

    As far as "there's a reason nobody does it".. I agree in general, but it doesn't hurt to experiment. Plus a lot of the time, the reason "nobody does it" is because it's not marketable.
  9. slinkp


    Aug 29, 2003
    brooklyn, NY, USA
  10. msquared


    Sep 19, 2004
    Kansas City
    This one rolls off at 300. Which (ignoring the SPL thing) is perfectly fine for me.
  11. Petebass


    Dec 22, 2002
    QLD Australia
    Don't forget overall SPL is a product of both sensitivity and watts. A low sensitivity driver can get loud enough if it has a high enough wattage rating. Though you'd be surprised how high the wattage would have to be.
  12. Ben Clarke

    Ben Clarke Liquidating to fund a new business. Buy My Gear!

    Jan 6, 2005
    Western NY
    Bill is too classy to push his own designs, but I've got to say that if portability and SPL are a priority, a 30lb. little box like a DR250a is very usable with a 5-string. I played a few tunes with my Ampeg B15 head section (power tubes are getting there, and 50W downhill with a tailwind) and MM Stingray5 in practice, and it was acceptable. I soon switched back to the Tuba24 on the bottom, though. It's just too nice!

    If you want an easy to live with single box, a ported 250a is tough to beat. Especially if you can build it yourself. If you run a DI into the PA (and why wouldn't you?), the extension of a Tuba is only for your own fun & pleasure.

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