Studio Technologies 65 - Manual (Page 24)

Issue 4, January 2004 Model 65 User Guide
Page 24 Studio Technologies, Inc.
for Surround
The other two push-button switches are
associated with the LFE Input. The function
of the +10dB gain switch is very simple; it
adds 10dB of LFE input sensitivity when
the switch in the +10 (on or in) position.
As expected, its associated LED will light
whenever the function is enabled. This
function is provided so that an LFE input
signal that has been level adjusted for
cinema playback can be correctly moni-
tored. Such formats reduce the nominal
level of the LFE signal by 10dB, allowing
greater headroom in the playback system.
This is technically clever, but can pose a
problem for non-theater playback environ-
ments. Using the +10dB gain switch allows
the gain to be made up and the monitoring
to be accurate.
The LFE input low-pass filter function is
provided to emulate the processing done
by some formats to the LFE channel. Unlike
the five main input channels, the LFE input
channel is often bandwidth restricted to
save digital “bits.” It’s important that an
audio “mix” maintain its integrity when such
LFE bandwidth restrictions are in place.
The LFE input low-pass filter function is
enabled by placing its switch to the LPF
(on or in) position. When enabled the LFE
signal is routed through a series of analog
filters which provide a 48dB-per-octave
slope with a –6dB frequency of 120Hz.
Philosophy dictates how the filter function
should be used. The function can be used
as a final “double check” to ensure that
material will maintain overall integrity when
digitally processed. Enabling the filter during
a final listening session should find the
spectral content remaining constant. If the
mix is impacted, content has been incor-
rectly routed to the LFE channel!
It’s also acceptable to leave the filter en-
abled at all times. This will ensure that an
audio mix will “hold up” when processed.
However, this may mask content remaining
in the LFE channel which, although it won’t
be present after processing, may be confus-
ing to mastering engineers or other person-
nel who monitor the original source material.
Remote Control Functions
The Model 65 provides three functions
that can be controlled by external sources:
LFE low-pass filter, LFE mute, and sub-
woofer mono. The first two functions are just
a means of remotely enabling functions that
are also controlled by front-panel push-
button switches. They effectively perform
a logical “OR” function with the front panel
buttons. The LED indicators on the front
panel will light whenever their respective
function is enabled, whether by means of
the front panel switches or the remote
control inputs.
The subwoofer mono function allows the
phase coherency of signals on the two
subwoofer outputs to be checked. When the
function is enabled signals destined for the
subwoofers are added (summed), reduced
in level by 6dB, and routed to both sub-
woofer outputs. Note that there is no LED
indicator associated with the subwoofer
mono function.