Speaker Design, Speaker Building: Loudspeaker Design & Construction

Band Pass

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The Band Pass loudspeaker enclosure

This is a design currently gaining in popularity for bass applications.  Further drivers would need to be added to handle mid and high frequencies.  The driver output is isolated and the vented output has a narrow band pass characteristic.  Such a design will usually surpass a similar bass reflex enclosure in terms of efficiency.

There are several common variations on the sealed rear chamber bandpass enclosures. 

  1. Single driver bandpass,
  2. Dual driver push/pull bandpass, drivers connected out of phase
  3. Push/pull compound bandpass, drivers connected out of phase
  4. Triple chamber bandpass, drivers connected out of phase
  5. Push/pull triple chamber bandpass
  6. Rear ported triple chamber bandpass

The bandpass is commonly employed in speakers such as the ‘Acoustimass’ and the versatile ‘Series II’ ranges by Bose®, as well as many subwoofers.  Bandpass is a good way of extending bass efficiency, but further drive units are required for full frequency coverage.

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