Alesis M1 ACTIVE - Page 14

About
the
Mt Actlye
o
Better
amplifier/speaker
coupling
for woofers.
e
Better
crossover
performance
working
into
a
constant
impedance
load.
r
Better
subjective
sound
quality
than high
level
(passive)
networks.
r
Easier
conkol
over
driver
sensitiviff
differences.
r
Easier
manipulation
of phase,
time delay,
resonance,
and
various
kinds
of
shaping,
contouring
and
equalization.
r
sgeSifically
in
the
case
of the
Mr
Active,
the wide,
mid-frequency
polar
response
of the
tweeter
can be utilized
down
to a low
1500H2
thereby
mutir,g
*or"
'
cohesively
with
the
6.5 non-woven
carbon fiber
(NWCF)
woofer.
Tii" lo*
crossover
is
only
possible
through
the use
of a very
steep,
electrotic
eighth-order
(48
dB per
octave
rolloff)
high
pass
filter.
The
Ml Active
power
supply
P"
M1
Active
employs
a regulated
switching power
supply.
This
type of supply
has previously
only
been available
in
amplifiers
sold at
the very
high
end of tire
iro
Audio
market.
Most power
amp
customers
are familiar
with the
large transformer
and output
capacitors
in
high quality
amplifiers.
These
large
components
are used
to lieep the
amplifier's
supply rails
as
close to DC
as possible.
For
traditional
supplies,
bigger
is
better.
Brt
by using Pulse
width Modulation
(PWM)
and
output
voltage
feedback in
the
M1.
Active,
we
have the
equivalent
of near-infinite
transfonner
and
output
capacitors,
but at
a fraction
of the cost.
PWM
provides
protection
from line
voitage
surges
that
would
otherwise
destroy
the
amplifier.
No user-replaceable
fuse
is required
because
nuisance
tripping
is
eliminated.
And finally,
PWM
practically
eliminates
hum
because
th9 line
frequency
$0ru)
transformer
is replaced
with
a very high
frequency (13Q000
Hz)
transfomrer.
The regulated-supply
rails
increase
the
ampMier dynamic
range
and
reduce
clipping
distortion
under heavy
loading.
The compact
size
of the supply
does
not
significantly
reduce
the
intemal
air
volume of the
speaker
cabinet.
And lastly,
fulI
power
can be maintained
even
with low
or
',flat-topped,,
line
voltages.
Note, however,
that
this switching
supply is
NOT
a univercal
voltage
type
that may
be used with
any input
voltage
in
any
country
simply by
changing
the cord.
lf
you
wish
to use thsMl
Actives
in
a country
whose line
voltage
ii other
than
120 volts
AC
they
must
be internally
modified
or uied with
a stepdown
transformer.
72
IUTI
ACrTG
RffiE
ilIAIIUAL