what is bass reflex?

Discussion in 'Archived Threads 2001-2004' started by felix_suwarno, Jan 17, 2002.

  1. felix_suwarno

    felix_suwarno Screenwriter

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    i was searching on onkyo's line of htb, and found "bass reflex" on the spec. what does that mean, really?

    i also found a tower speaker that doesnt have subwoofer built in. i wonder why does it have to be that way? what is the advantage of having more space for the small woofers? te speaker only has 2 3.5 inch woofers and 1 inch tweeter.

    thanks in advance
     
  2. Jason Coleman

    Jason Coleman Auditioning

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    Bass reflex is another way of saying it's a ported speaker. You'll see in many sub-woofers an opening into the speaker enclosure. The purpose of this enclosure is to take some of the energy which is used in moving the woofer cone backwards, and rather then absorb it into the enclosure, turn it back outward through the port, increasing the efficiancy of energy used. This gives you more "thump" but at the cost of some accuracy in the reproduced sound. Badly tuned ports will make it sound bad, hollow, or even quieter then it could be.

    -Jason
     
  3. Ted Lee

    Ted Lee Lead Actor

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  4. felix_suwarno

    felix_suwarno Screenwriter

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    thanks for the replies, howefer there a few things left.

    "This gives you more "thump" but at the cost of some accuracy in the reproduced sound. "

    what is the meaning of accuracy there? how does an innacurate sound sound like?

    and about tower speakers without subwoofer. is there any advantage at all by using bigger enclosure? i mean, i think the manufacturer is just wasting wooden material just to build that kind of tower.

    thanks in advance
     
  5. felix_suwarno

    felix_suwarno Screenwriter

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    bump! please, i still need more explanation on this
     
  6. Greg_R

    Greg_R Screenwriter

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    With a ported design you get greater SPL at lower frequencies. The tradeoff is that the speaker's roll off is steeper (less natural). However, driver selection, cabinet design & other factors play a _much_ larger part (i.e. don't purchase design X because it's not ported). Some of the best commercial subs use a ported design (Aerial SW-12, SVS, Hsu, etc.) A poorly designed or constructed subwoofer cabinet can resonate (causing unwanted distortion). This distortion can be very loud (i.e. "one note bass").

    The size (volume) of the cabinet determines how the driver will behave (sound). The volume needs to be customized for the particular driver and application. Larger (properly constructed) cabinets can lead to better bass response and/or power handling. If you're interested in more information, I'd recommend Dickenson's "Loud Speaker Design Handbook" which explains all of this in detail (I oversimplified my explanation).

    To summarize: Purchase what sounds good to you. There are many speaker designs that use ports that are very accurate and clean...
     
  7. Cees Alons

    Cees Alons Moderator
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    More "thumb" means: the bass will go lower in a properly tuned reflex-sub than would be possible (with the same driver) in a closed sub.
    But there are some phase effects for different frequencies that are often referred to as "less accurate": it could hurt the harmonics build of those tones. Mostly, those phase difference occur in the neighbourhood of the lowest frequencies (the ones to which the port is tuned), so it's a little bit less important, especially not for movie soundtracks. But, of course, this judgement also depends on your taste.
    BTW a ported sub should never be driven with frequencies LOWER than the port's frequencies (but if that lowest frequency is about 20 Hz, there's hardly a chance it will occur in practice [​IMG]).
    Cees
     

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