Aboui {ic mt Actlve
ozone, direct sunlight, heat and humidity.
Therefore, after an initial break-in period
(about
20 hours),
the sound
should remain virtually unchanged for the life of the
product.
Alesis'proprietary
design tweeter feafures
a pure
Japanese
silk
dome, an intemal
pole'piece mounted
phasing plug and
low viscosity ferrofluid formulated
specifically to
retain the best
balance of transient response
to power handling. The
shielded tweeter
utilizes a vented
pole piece with a
separate rear chamber to
lower
the free air resonance.
The very low
1500H2 crossover point
of this tweeter produces
an
extremely wide
dispersion, low
distortion signal
within the critical midrange
frequmcies. It is
these frequencies
which are often
the most problematic in
terms of
getting
"right"
during a mix. The
tweeter is
designed for an
optimal
response
for
non-fatiguing,
long
ter:n, high level,
nearfield mixdowns.
This desigrr
results in a
flat,
linear
mix when played
back
on home
or car systems from
appropriate distances.
Magnetic
shlelding
Your
Ml Actives
ate at home in
recording
environments wherein
video is a major
component. They
are magnetically
shielded
for use in fairly
close
proximity (3,,
minimum) to
a computer
monitor
or video screen.
(Non-shielded
components
can
make the colors
of a screm
"smear"
or appear out of focus
if the speaker is
too close.)
Magnetic shielding
was designed into
both the woofer
and the tweeter from
the
beginning so
that the
system exhibits
about 10 gauss
(worst
case) leakage.
Shielding
of both the woofer
and
the tweeter
is accomplished
by the use of a second
opposing-
field-oriented
"bucking"
magnet.
The
tweeter has an additional
sixteen-gauge
steel
cup encasing
the entire
magnetic structure.
The Ml
Actine
bi.amplifiers
&
electronic
crDssouers
The M1 active
uses
a
75W
woofer
amp and a 25W
tweeter
amp
along
with 86
order
high and
low pass
electronic
crossover filters
cmtered at 1500H2.
Electronic
crossovers, which
separate
the frequencies
before being
sent to the amplifiers,
have
fewer phase
problems
and less
power loss
than the traditional passive
crossover
used
after
the amplifier. Eighth-order
filters are extremely
steep
(48
dB
per
octave),
which
minimizes the
interaction
between
woofer and tweeter
near the crossover
point.
Additionally,
the high pass (tweeter)
section of this
system employs an
electronic
time alignnent
circuit. Thus
the
"launch"
of
frequencies
from both the woofer
and
the
tweeter will
originate at
exactly the same time.
There are several
advantages
to usingbuilt-in
amplifiers and
active
(elechonic)
crossovers
versus
a
passive
network
system, most
of which have
bem
previously
enumerated
in Vance
Dickason's
"Loudspeaker
Design
Cookbook":
r
Lower intermodulation
distortion
due to amplifier
operation over a more
narrow
bandwidth. AIso,
clipping caused
by low frequency
overload is reduced,
being
limited
to only one driver
within a
two
driver
system.
e
Increased
dynamic range. The
Ml Active's ZSW
and 25W amplifiers
in their
bi-
amp setup
will clip at about
the
same
levels as
one 200W amplifier
operating into
a
passive
crossover.
r
Improved
transient
response.
If,IACTN'E
REEHG
il|ATUAL
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