..
levels
of
the delay functions into the
INPUT
MIX,
and
mix
some
of the input
into the
OUTPUT
MIX.
In
general
an
effect
can
be
spatially
enhanced
by
using
the
INPUT
MIXER
OUT
as the
left
channel
and
the
MASTER
OUTPUT
as the
right
channel (or vice
versa).
A proper balance
between
the
two
can
be
made
by
adjusting the
OUTPUT
MIX
MASTER
control.
In
addition to synthesizing
stereo,
M.93
can
be
used to enhance a stereo
source with spacious ambiance: the output
can
be
mono,
stereo,
or syn-
thesized quad. Bring the
left
channel
of
a
stereo
source to the
INPUT
and
the
right
channel
of
a
stereo
source to the
AUX
INPUT.
Set
up
an
input
mix
predominantly
of
IN,
a smaller
amount
of
AUX,
and
recirculation
from
delay
taps A
and
B.
Use
an
output
mix
predominantly
of
AUX
with a smaller
amount
of
IN,
phase
inverted,
and
the delay taps A
and
B.
Take
a
mono
output
from
the
MASTER
OUTPUT.
For
a
stereo
output use the
INPUT
MIXER
OUT
as
left
and
the
MASTER
OUTPUT
as
right.
To
make
quad, use
DELAY
A
and
B outputs for the
rear
channels.
An
alternative
approach
for
quad
is
to use the original source
for
front
channels
and
the
stereo
outputs
of
M.93
for
the
rear
channels
(either
INPUT
MIXER
and
MASTER
or
DELAY
A
and
B output
pairs).
(The
DELAY
A
and
B
outputs
are
likely
to
be
superior for
rear
channels because they
do
not con-
tain
any
direct
source
which
might lead to confusion in
localizing
the sound.)
3.6
SOUND
REINFORCEMENT*
If
a
sound
comes
from
two
different
sources but
one
delayed
40
msec
or
less
with
respect
to the
other,
then the
sound
will appear to
be
coming
from
the
first
(earlier)
source
and
not the second (providing
that
the second
is
not
more
than
10
dB
louder than the
first).
This
is
called
the
11
precedence
..
effect
and
because
of
it
amplified
sound
in a
hall,
sufficiently
delayed,
seems
not
to
come
from
the amplified source but
from
the real source. Since
sound
travels
one
foot in about .9 msec, delaying
an
amplified source
by
1
msec
for
every
foot
that
it
is
from
the real source insures
that
sound
from
the real source
reaches the
listeners
first.
M.93
provides
two
independent delays
from
DELAY
A
and
B outputs
which
can
be
used
for
sound
reinforcing speaker systems
at
two
distances
from
the source.
In
this
application
M.93
is
used as a simple
*Klepper,
David
L.,
11
Application
of
Digital
Delay
Units to
Sound
Reinforcement
Systems
11
, Lexicon Application Note:
AN-2,
1975.
33
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