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Stacking arrangement for multiple cabinets...

Discussion in 'Amps and Cabs [BG]' started by GeorgiaHonk, Mar 24, 2004.


  1. Hey folks...newbie here. I've noticed that many of you utilize multiple cabs for live performances, and the general rule of thumb seems to be "tens on top, fifteens (or 18s) on the bottom." Is this really the rule, and why? Is there a physics principle concerning the dissipation of frequencies at work here, or do you just do it because its the generally accepted thiung to do?

    I personally have never used more than one cab at a time, so I never encountered the situation. But I am considering multiple cabs when I purchase my new rig.

    Thanks in advance,
    Roger
     

  2. Yes! Physics at work right there. Higher frequencies are much more audible to the human ear. Get the cab with more higher frequencies closer to ear level and it's going to sound "louder".

    :bassist:
     
  3. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Plus low frequencies like to roll alond flat surfaces such as floors and walls. Remember that next time you're setting up a home stereo and are thinking about putting the sub on a bookshelf (As I have seen many people do). It robs the sytem of a substantial amount of bottom end.
     
  4. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    Yes, there are several important physics principles at work. The most important one for bass players is the frequency dependent "absorptivity" of materials. Take, for instance, y'r average speaker cab made of wood. At "low mid" frequencies, say 200-400 Hz, most of the sound reflects off the inner surfaces of the cab, and the air comes out of the ports (and hence the low-mid "woof" that we all know and love). At "low" frequencies, like 31 Hz (low B), the wood turns into a sieve. The absorptivity increases from 4 percent to around 30 percent, which means that a lot of the acoustic energy goes straight through the cab and into the floor. Since an 18" speaker will generally deliver much more energy at very low frequencies, people put these on the bottom to get that mondo low frequency bass that you can't necessarily "hear", but you can definitely "feel" (it makes your pant legs vibrate as it travels up your legs and into your gon... well, you get the picture, loosens your bowels, that kind of thing). Which is also why it generally takes a lot more power to get low frequencies "out there" into the audience. Petebass is right, the lows tend to dissipate out around corners, and go places where higher frequency energy generally can't. And guyplaysbass is right too, you want the mids and highs at ear level as much as possible, 'cause that kind of sound tends to push "straight out" from the speakers (to varying degrees, depending on the shape of the speaker and the shape of the cab, etc). The 15 or 18 on the bottom will give you that gut wrenching low end, especially if you have an efficient cab design like a folded horn or something, that also builds up lots of energy inside the cab. The old Acoustic 301's come to mind (JPJ, Stanley, Jaco, etc - a lot of great bass players have used these type speakers, for exactly that reason).