13
SETTING LEVELS
Input Gain
Adjustment
Use the
p
and
q
buttons to cycle to the
INPUT gain
and
OUTPUT gain
screen:
With the
w
cursor set as shown above, the
t
and
u
buttons allow
adjustment of the input gain over a ±15dB range in 1dB steps. This
setting applies to either the analog or the digital inputs, whichever is
selected.
There is no provision for independent gain settings for
analog and digital input signals.
If the two input modes are used
alternately, then input gain may have to be reset when the selection
is changed.
Refer to Page 8 for proper circuit board jumper positions for the
analog line inputs. For typical studio-level program lines circuit
board jumpers will be set to the default
position.
Analog Input
Gain
(Studio Levels)
The input gain structure is such that, with a nominal input line
level of 0dBu and an
INPUT gain:
setting of
0
d
B
,
AGC GAIN
should
wander slowly in the center of its range for most program material.
This means that a t4dBm studio program line would require
an
INPUT gain:
setting of
-4
d
B
. Similarly, a +8dBm program line
would require a
-8
d
B
setting.
Analog Input
Gain
(Semi-Pro
Equipment)
Disco mixers, consumer CD players and other gear of that genre has
typical line levels in the 300mV range, or about 10dBu. When con-
necting the
ANALOG INPUT
(s) to this equipment, observe the con-
nection instructions on Page 8, and set the circuit board input gain
jumpers in the 10 position as described on the same page.
Digital Input
Gain Structure
When the AES/EBU digital input is selected, an
INPUT gain:
setting
of
0
d
B
matches a digital 0VU level of 20dBFS.
INPUT gain:
may
be adjusted ±15dB from this value.
Regardless of the input mode selected,
INPUT gain:
is optimally set
when the
AGC GAIN
bargraph hovers about the
0dB
point on the
scale, or when
INPUT gain:
is adjusted for a desired amount of
COMPRESSION/LIMITING
when AGC is not used.
Input Overload
Alarms
The Model 261 has bodacious internal headroom in both the analog
and the digital domains. There are two alarms, however, that moni-
tor program waveform excursions to alert the operator should in-
ternal levels reach about 95% of digital full-scale.
The primary alarm gives both a flashing
INPUT OVERLOAD
indication
on the Status screen and a closure on the rear-panel
INPUT OVER-
LOAD
terminal.