S
UBWOOFER
E
NCLOSURE
T
YPES
In the car audio world there are 5 types of subwoofer enclosures commonly used; Infinite Baffle, Sealed Box, Vented Box,
Single-Vented Band-Pass, and Dual-Vented Band-Pass. No single design is superior because each has its own
compromises in performance, power handling, and design/construction complexity. You need to make the choice based
upon personal listening habits and requirements.
Having “Multi-Box” design characteristics, your Blaupunkt subwoofer performs remarkably well in ALL installations, but is
optimized for Sealed, Vented, and Single-Vented Band-Pass configurations due to its moderate Qts values. Below is a
summary of these 5 popular enclosures. More importantly their respective advantages and disadvantages are noted so an
intelligent choice can be made regarding the best box for you.
INFINITE BAFFLE
(a.k.a. “Free-air”) is simply a woofer installed in the back shelf of the
car that uses the trunk as the enclosure.
Advantages:
simple installation and adequate
performance;
Disadvantages:
only moderate sound pressure levels and poor power
handling.
SEALED BOX
(a.k.a. “Closed Box”) offers one of the best compromise in performance
and power handling.
Advantages:
simple box construction, high power handling,
excellent transient response, and smooth low frequency roll-off.
Disadvantages:
moderate to large box sizes, moderate efficiency, moderate sound pressure levels.
VENTED BOX
(a.k.a. “Ported Box” and “Bass Reflex”) is simply a sealed box but with a
specifically tuned tube inserted. It extends the low frequency response compared to a
sealed box.
Advantages:
low cut-off frequency, low distortion in its operating pass-band,
excellent efficiency, good transient response, moderate power handling (in its pass-band),
and small box sizes.
Disadvantages:
complex design and limited power handling if
driven hard at very low frequencies (below port tuning frequency).
SINGLE-VENTED BAND-PASS
(a.k.a. “4th Order Band-Pass”) is one of the best designs
for the car. It is basically a “compromise” between a sealed and vented box in
performance and reliability.
Advantages:
small box volumes, extended low frequency
performance, and can be used with VERY high power amplifiers.
Disadvantages:
slight
drops in efficiency compared to a vented box and increased box design and construction
complexity.
DUAL-VENTED BAND-PASS
(a.k.a. “6th Order Band-Pass) is unfortunately often used in
the car as an acoustical “fog-horn” - lots of high-SPL but marginal tonal quality if the
enclosure isn’t precisely constructed.
Advantages:
tremendous SPL’s from VERY small
boxes
Disadvantages:
VERY complex construction and susceptibility to cone over-
excursions for frequencies outside its operating region if a high quality electrical filter is
not used.
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