Speaker enclosure
types for all applications, what type is best for your project?
Speaker enclosure types
woofer box types
Below are examples of automotive
sub woofer enclosure
boxes) for many different applications.
Designing
a car audio woofer system:
With any high-end audio sound
installation, you should stick to a very logical and
straightforward procedure. The most important
factors are size, performance, cost, and ease of
construction.
First decide how much room you
would like to dedicate
to your woofer system; usually, the bigger the
box, the better. This will inevitably
affect the other parameters of the design process.
High-performance systems usually require large
woofers or enclosures. This will typically raise
the price of the system and increases the amount of
time required for installation.
Once you
have decided on how much space your woofer box
will occupy, you should then determine what type of
enclosure is right for your particular application.
The simplest type of woofer system is the "infinite
baffle." The infinite baffle is simply a
barrier that separates the front of the speaker from
the back of the speaker; this barrier is called a
baffle board. A typical infinite-baffle installation
in an car stereo sound system consists of mounting the
woofer's on the rear deck of the vehicle or on the
back of the rear seat. As with any infinite-baffle
design, it is very important that sound waves do not reach from the rear of the speaker to its
front. If this occurs, cancellation will occur and
bass response will suffer.
An infinite-baffle
system is usually the simplest way to install
woofers in your vehicle. You should expect good
performance from this type of installation, and since
there are no enclosures to build or design, installation
time and cost are kept to a minimum. Unfortunately,
there are several disadvantages to the infinite
baffle. When a speaker is mounted in an enclosure,
the air inside the box acts like a spring
against the speaker cone, and the buildup
in pressure provides mechanical damping and prevents
excessive speaker cone movement. But an infinite-baffle
installation does not use an enclosure, so the
damping is poor, resulting in "hang-over"
and lack of definition. The power handling of the
speaker will also be reduced since the infinite
baffle provides very little control over the speaker cone
excursion.
What type of enclosure
is best for your project?
Sealed
Sealed Box
This is
a sealed enclosure that uses a calculated volume of air
as a spring" to help dampen and control woofer cone
movement. Sealed enclosures can have a relatively smooth
roll-off and flat response.
Pro's:
Small boxes, higher power handling, excellent dampening
and transient response, easy to design and build, can be
forgiving of design and construction errors.
Cons:
Efficiency vs. output
Ported
Ported Enclosure
Ported
enclosures use a tuned port or vent to increase output
at lower frequencies. Air inside the vent acts like a
piston or motor that moves in the phase with the woofer
reinforcing frequencies.
Pros:
Increased efficiency, increased low frequency output,
relatively low distortion.
Cons:
Larger enclosures less tolerant of design/construction
errors, no woofer control below tuning frequency.
Aperiodic
Aperiodic
Aperiodic enclosures utilize an external membrane to
dampen the woofer and flatten out the impedance curve of
the enclosure.
Pro’s:
Extremely small enclosures, very flat response,
excellent low extension.
Cons:
Low efficiency, usually needs larger subwoofers to
perform, EXTREMELY difficult to design and tune
properly.
Isobaric
Isobaric (most
commonly “push-pull”)
An
enclosure that uses two woofers mounted face to face,
one wired reverse polarity. This alignment effectively
cuts the vas in half. The general rule of thumb for an
isobaric enclosure is twice the woofers, twice the
power, and half the box size3.
Pros: Very small enclosures, increased power handling, driver
non-linearities canceled out (lower distortion).
Cons: Very low efficiency, due to the small size of the
recommended enclosures for our woofers an isobaric
alignment is not practical.
Sealed Inverted
Sealed Box (Inverted woofer)
Often
mistaken for an Isobaric set up, this is simply a woofer
mounted in a sealed box with the magnet facing out.
This is done for cosmetic or depth reasons only. There
is no sonic benefit.
Acoustic Coupled
Acoustic Coupled
Two
woofers sharing a given volume.
Pro’s:
Can be easier to build than a divided enclosure.
Cons:
Output can be affected each driver relieving slightly
different information, enclosure is more likely t flex
without the additional bracing of the divider (usually
need additional bracing).
Infinite Baffle
Infinite Baffle: a.k.a. Free-air
A
woofer mounted to a surface that isolates the front wave
from the back. (A woofer in an enclosure which has a
larger vas than the woofers vas).
Pros: Very low system resonance, minimal space used in the
vehicle.
Cons:
Limited efficiency/output, no control of the woofer
below its fs, usually very difficult to seal front wave
from back.
Single Reflex Band pass
Single reflex band pass
Sealed
enclosures that play into a tune enclosure that acts an
s a low pass filter... This increases efficiency within
the “pass band” or usable frequency range of the
enclosure.
Pros:
Can be made very efficient within the pass-band”, can be
designed for increased gain in a band of frequencies,
increased power handling within the band.
Cons:
Distortion hard to hear so, it’s very easy to destroy
woofers, increased gain designs sacrifice low end
response, relatively large enclosures very difficult to
design and build, very sensitive to design/construction
errors.
Dual Reflex Band pass
Dual
Reflex band pass:
A
ported enclosure in which the woofer plays into a
tune-ported enclosure that acts a low pass filter. This
creates a highly efficient system with two resonance
frequencies.
Pros: Can be even more efficient than a single reflex band
pass; excellent dampening at resonance, increased power
handling at resonance
Cons:
EXTREMELY difficult to design/construct, not forgiving
of designs/construction errors like a ported enclosure
it looses woofer control below f3, steep low frequency
roll-off (24db) very large enclosures.
Ported SPL
Ported (SPL)
Extremely large enclosures with very large port area.
These enclosures have high ripple and are used to
pinpoint and boost a specific frequency.
Pro’s: Very high SPL
Con’s:
Very high f3 (woofer control is lost below f3), trying
to reproduce musical frequencies will result in woofer
failure.
Transmission Line
Labyrinth
A form
of Transmission Line, this enclosure uses a port that is
a fraction of a wave length to couple with the woofer.
Pros:
Can be built to maximize out put at a particular
frequency (SPL purposes)
Cons:
Difficult to build, giant enclosures, easy to blow
woofers, not practical unless used for SPL competition,
experimental.
Enclosures
Explained
Here you will find more detail
about each speaker box and which one is right for your
application.
