Studio Technologies 68A 2005 - Manual (Page 34)

Issue 2, January 2005 Model 68A/69A User Guide
Page 34 Studio Technologies, Inc.
for Surround
As expected, in the exclusive solo mode
pressing a channel button will cause that
channel to be soloed. But, in addition, any
other channel or channels being soloed
will go back to their normal, non-solo
condition. Thus the exclusive solo mode
allows rapid “soloing” of individual chan-
nels. Should more than one channel need
to be simultaneously soloed, simply push
and hold a channel button, then add the
extra channels by momentarily pressing
their buttons.
Remote Controls
Three remote control signals can be con-
nected to the system and confi gured for
the desired operating characteristics: mute
all, dim, and input select. When remote
mute all is activated the LED on the Model
69A associated with mute all will fl ash.
If mute all was already active when the
remote mute all function is activated, the
LED will change from being steadily lit to
fl ashing.
When Remote Dim is activated the LED
on the Model 69A associated with the dim
function will fl ash. If dim was already active
when remote dim is activated, the LED will
change from being steadily lit to fl ashing.
When remote input select is activated,
the LED on the Model 69A associated with
the selected input will fl ash. If the function
is set for exclusive, no other LEDs will be
lit. If the function is set for non-exclusive,
the LED associated with remote input
select will fl ash, while the LEDs associated
with any other active inputs will remain
steadily lit.
Technical Notes
Downmix
The downmix function is implemented in
the Model 68 Central Control’s hardware
using simple analog circuitry. From the fac-
tory downmix is defi ned as: center dropped
in level by 6 dB and routed to left and right;
left surround dropped in level by 3 dB
and routed to left; right surround dropped
in level by 3 dB and routed to right; LFE
muted. By making simple resistor changes
the level changes can be easily revised. In
addition, provision has been made to allow
the LFE signal to be routed to the left and
right channels during downmix.
While no soldering is required, a com-
petent technician is required to perform
any changes to downmix function. This
will help to ensure a safe and success-
ful modifi cation. Page 5 of the Model 68A
schematic contains the circuitry that imple-
ments the downmix function. Please con-
tact [email protected] for a copy
of the schematic.
Bandpass Filter
The bandpass fi lter associated with the
mono-to-center mode is created by cas-
cading (connecting in series) a high-pass
and a low-pass active fi lter. Each fi lter is
a Sallen-Key type, with a 12 dB-per-octave
response. The high-pass fi lter has a nomi-
nal –3 dB point at 100 Hz; the low-pass
at 5 kHz. For a detailed description of the
fi lters, refer to page 5 of the Model 68A
schematic diagram. It is available upon
request from [email protected].
High-Pass Filter
Components were selected at the factory
so that the high-pass fi lter section’s output