Carvin FET1000 Instruction Manual - Page 25

Passive

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FET Series Power Amplifiers Biamping and Triamping Speaker Systems Section 5 The simplest type of multiple driver loudspeaker system employs two drivers: a high frequency driver (a "tweeter") and a low frequency driver (a "woofer"). Our first inclination might be to apply the full frequency range signal from the amplifier to both drivers by wiring them in parallel, but this approach would have some serious problems. First, most tweeters would be destroyed by the low frequency energy of the full range signal because it would drive the tweeters diaphragm through very wide excursions and tear up the suspension. Then, in the range where the frequency response of the two drivers overlaps, there would be too much output from the combined system. That is, the system would have a "peak" in the midrange region where the drivers have overlapping frequency response. To make matters worse, the tweeter would typically be louder than the woofer. The solution to these problems is to use a crossover network to block the low frequency energy from the tweeter and combine the woofer and tweeter into a full range speaker system. There are two general types of loudspeaker crossovers, active and passive. Passive Crossovers The passive type is the simplest, and is the type used most often. For example, home Hi-Fi speakers almost always use passive crossovers. A passive crossover is located in the signal path between the power amp and the speaker components. It is usually located inside the speaker enclosure along with the drivers. A passive crossover consists of passive components (resistors, capacitors and inductors) with a high power rating and acts directly on the speaker level signal from the power amplifier. It's main advantage is that it allows one power amplifier to drive a complete full range loudspeaker system. See Figure 5-1 below. High-Pass Output Tweeter lJno level signal from mixer or preemp Power Amplifier Passive Crossover Speaker Level Signal Low-Pass Output /1 /) Woofer Figure 5-1: Two-Way Loudspeaker with a Passive Crossover 5-2

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FET
Series
Power
Amplifiers
Biamping
and
Triamping
Speaker
Systems
Section
5
The
simplest
type
of
multiple
driver
loudspeaker
system
employs
two
drivers:
a
high
frequency
driver
(a
"tweeter")
and
a
low
frequency
driver
(a
"woofer").
Our
first
inclination
might
be
to
apply
the
full
frequency
range
signal
from
the
amplifier
to
both
drivers
by
wiring
them
in
parallel,
but
this
approach
would
have
some
serious
problems.
First,
most
tweeters
would
be
destroyed
by
the
low
frequency
energy
of
the
full
range
signal
because
it
would
drive
the
tweeters
diaphragm
through
very
wide
excursions
and
tear
up
the
suspension.
Then,
in
the
range
where
the
frequency
response
of
the
two
drivers
overlaps,
there
would
be
too
much
output
from
the
combined
system.
That
is,
the
system
would
have
a
"peak"
in
the
midrange
region
where
the
drivers
have
overlapping
frequency
response.
To
make
matters
worse,
the
tweeter
would typically
be
louder
than
the
woofer.
The
solution
to
these
problems
is
to
use
a
crossover
network
to
block
the
low
frequency
energy
from
the
tweeter
and
combine
the
woofer
and
tweeter
into
a
full
range
speaker
system.
There
are
two
general
types
of
loudspeaker
crossovers,
active
and
passive.
Passive
Crossovers
The
passive
type
is
the
simplest,
and
is
the
type
used
most
often.
For
example,
home
Hi-Fi
speakers
almost
always
use
passive
crossovers.
A
passive
crossover
is
located
in
the
signal
path
between
the
power
amp
and
the
speaker
components.
It
is
usually
located
inside
the
speaker
enclosure
along
with
the
drivers.
A
passive
crossover
consists
of
passive
components
(resistors,
capacitors
and
inductors)
with
a
high
power
rating
and
acts
directly
on
the
speaker
level
signal
from
the
power
amplifier.
It's
main
advantage
is
that
it
allows
one
power
amplifier
to
drive
a
complete
full
range
loudspeaker
system.
See
Figure
5-1
below.
lJno
level
signal
from
mixer
or
preemp
Power
Amplifier
Speaker
Level
Signal
High
-Pass
Output
Tweeter
Passive
Crossover
Low
-Pass
Output
Woofer
/)
/1
Figure
5-1:
Two
-Way
Loudspeaker
with
a
Passive
Crossover
5-2