Owner's Manual
REFERENCE
®
VENTED
ENCLOSURES
A
vented
enclosure
acts
like
a
sealed
enclosure
at
frequencies
above
its
tuned
(resonance)
frequency,
At
resonance
(which
is
defined
by
the
vent),
the
vent
produces
the
majority
of
sound-
the
subwoofer
cone
is
nearly
stationary
while
the
air
inside
the
vent
vibrates.
This
provides
greater
mechanical
power
handling
at
and
above
resonance,
but
reduced
mechanical
power
handling
below
resonance.
Since
the
subwoofer
cone
and
voice
coil
don't
move
much
at
resonance,
airflow
across
the
voice
coil
is
minimized
and
thermal
power
handling
is
reduced
slightly
at
resonance.
Vented
enclosures
provide
better
efficiency
in
the
40Hz
-
60Hz
range,
at
the
expense
of
sound
output
in
the
lowest
octave
(below
40Hz).
The
use
of
an
infrasonic
filter
is
recommended
with
vented
enclosures.
An
optimum
vented
enclosure
for
a
Reference
Series
subwoofer
is
larger
than
an
optimum
sealed
enclosure.
See
accompanying
data
sheet
for
specific
enclosure
dimension
requirements.
VENTED-ENCLOSURE
PERFORMANCE
ADVANTAGES
•
An
optimum
vented
enclosure
has
greater
efficiency
and
higher
output
in
the
40Hz-
60Hz
range
than
an
optimum
sealed
enclosure.
•
An
optimum
vented
enclosure
provides
a
greater
sensation
of
bass
than
an
opt
i
mum
sealed
enclosure.
·A
1000s
or
1200s
subwoofer
in
an
optimum
vented
enclosure
will
require
less
amplifier
power
to
achieve
a
given
acoustic
output
(down
to
the
enclo
s
ure's
resonance
frequency)
than
in
an
optimum
sealed
enclosure.
VENTED-ENCLOSURE
PERFORMANCE
TRADE-OFFS
•
Reduced
output
in
the
lowest
octave
(below
40Hz).
•
Reduced
mechanical
power
handling
below
the
enclosure's
resonance
frequency,
The
use
of
an
electronic
infrasonic
filter
is
strongly
recommend-
ed,
to
reduce
the
chance
of
overdriving
the
subwoofer
below
the
enclosure's
resonance
frequency.
•
An
optimum
vented
enclosure
will
always
be
larger
than
an
optimum
sealed
enclosure
.
VENTED-ENCLOSURE
CONSTRUCTION
Vented-enclosure
construction
is
more
difficult
than
the
construction
of
a
sealed
enclosure.
The
enclosure
volume
and
port
dimensions
have
a
specific
relationship
with
the
physical
and
electromechanical
characteristics
of
the
subwoofer,
requiring
that
the
recommended
enclosure
volume
and
port
characteris-
tics
be
strictly
observed.
As
with
sealed
enclosures,
use
medium-density
fiberboard
(MOF),
glue
and
screws
to
construct
the
enclosure,
and
seal
all
joints
with
silicone
caulk.
THE
INFINITY
RECOMMENDATION
1000s
and
1200s
subwoofers
in
vented
enclosures
are
recommended
for
enthusiasts
who
prefer
accentuated
bass
response,
for
those
who
have
plenty
of
cargo
space
to
devote
to
a
subwoofer
enclosure
and
for
those
who
will
use
a
less
powerful
amplifier
to
drive
their
subwoofer.
The
volume
and
port
dimensions
indicated
on
the
included
techn
i
cal
data
sheet
must
be
followed
precisely
to
ensure
optimum
performance.
BAND-PASS
ENCLOSURES
Band
·
pass
enclosures
can
provide
the
most
output
from
any
amplifier
and
subwoofer
combination
over
a
limited
band
of
frequencies,
but
that
additional
output
comes
at
the
expense
of
sonic
accuracy
,
Ba
nd-
pass
enclosures
combine
a
sealed
or
vented
enclosure
that
houses
the
subwoofer
along
with
a
vented
chamber
into
which
the
subwoofer
outputs
its
sound.
The
vented
chamber
acts
as
an
acoustic
low·pass
filter
which
attenuates
hi
gh
frequencies
in
the
subwoofer
's
output.
That
attenuation
of
high
frequencies
can
make
it
very
difficult
to
hear
amplifier
and
speaker
distortion;
consequently,
you
may
not
be
able
to
determine
when
the
subwoofer
is
in
danger
of
being
damaged.
See
accompanying
data
sheet
for
specific
enclosure
dimension
requirements.
BAND-PASS
-
ENCLOSURE
PERFORMANCE
ADVANTAGES
•
An
optimum
band-pas
s
enclosure
provides
higher
output
over
a
limited
bandwidth
than
an
optimum
enclosure
of
any
other
type
,
BAND-PASS-ENCLOSURE
PERFORMANCE
TRADE
-
OFFS
•
Band-pass
enclo
s
ures
achieve
high
output
at
the
expense
of
sonic
accuracy.
•
An
optimum
band-pass
enclosure
has
a
more
limited
bandw
i
dth
than
an
optimum
enclosure
of
any
other
type.
•
The
enclosure
's
low
-
pass
filter
characteristics
can
make
it
difficult
to
hear
if
the
subwoofer
is
in
danger
of
being
damaged.
•
An
optimum
band-pass
enclosure
is
usually
larger
than
an
optimum
vented
enclosure
.
EN
BAND-PASS-ENCLOSURE
CONSTRUCTION
Band
-
pass-enclosure
construction
is
more
difficult
than
vented-box
construction
and,
as
with
vented
enclosures,
the
design
parameters
for
the
vented
section
must
be
followed
carefully.
(The
sealed
section
is
more
forg
ivi
ng
of
small
design
and
construction
variations.)
Fortunately
,
there
are
many
prefabricated
band·pass
enclosures
that
are
designed
to
extract
the
most
output
possible
from
nearly
any
subwoofer.
Prefabricated
band·pass
enclosures
are
strongly
recommended
if
you
must
have
a
band-pass
enclosure.
If
you
choose
to
build
your
own
band-pass
enclosure,
use
medium-density
fiberboard
(MDF),
glue
and
screws
to
construct
the
enclosure,and
be
sure
to
seal
all
joints
with
silicone
caulk.
THE
INFINITY
RECOMMENDATION
Band-pass
enclosures
are
recommended
only
for
enthusiasts
who
want
high
sound-pressure
levels
(SPL)
without
regard
for
sonic
accuracy,
If
high
SPL
AND
great-sounding
bass
are
your
goals
,
choosing
a
vented
enclosure
is
recommended
instead.
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