15
pressing the HDD key. If the inputs are in line level mode, phantom power will not activate from the
shortcut keys and must be activated from the menus. Phantom power is linked when the inputs are
linked.
(See Input Linking)
Input Limiters (mic-level only)
Microphone inputs 1 and 2 each have a limiter circuit designed to prevent input overload. In nor-
mal operation, with proper gain settings, the limiters should rarely engage. When activated, these
limiters will prevent unusually high input signal levels from clipping the analog input stage of
the preamp. The front panel LIM LED (
) shows that the limiter is engaged. Limiter activity is
indicated by additional front panel LEDs, one for each input channel (
). The input limiters are
active only with mic-level inputs. The limiters are engaged by (factory) default.
When limiters are engaged, audio on channels 1 and 2 is limited to
−
6 dBFS.
Microphone Level Control
Microphone gain is controlled by the front panel recessed knobs. The gain control adjusts an analog
gain stage and functions similarly to the input trim on a mixing console or stand-alone microphone
preamplifi er. Gain is controllable over two ranges, normal and low.
Gain Range (microphone-level only)
The microphone inputs operate in two gain ranges, normal and low. The normal range controls input
gain from 25 dB to 70 dB of gain. The low range controls input gain from 10 dB to 55 dB. The low
range is useful for high SPL recording environments.
High-Pass Filters (microphone-level only)
The high pass fi lters on the microphone inputs use a combination of analog and digital fi lters to re-
duce sensitivity to low frequency signals. When the high-pass is engaged on an input, its front-panel
LED illuminates to indicate it is active (
). The fi rst pole of the high-pass circuit is an analog fi lter
at 40 Hz, 6 dB per octave and is part of the microphone preamplifi er circuit. Additional poles of
high-pass fi ltering are done in DSP.
Several frequency and slope combinations are selectable, including corner frequencies of 40, 80, 160,
or 240 Hz, and fi lter slopes of 12 dB, 18 dB, or 24 dB per octave. The high-pass is selected for each
input independently.
Shortcut
: The fi lters can be toggled with a two-key combination. Press and hold the
LCD back-
light key and press the
menu key for channel 1 high-pass. Press and hold the
LCD backlight
key and press the
HDD key to toggle channel 2 high-pass. The high pass fi lters are linked when
the inputs are linked.
(See Input Linking)
Line-Level Gain Control
When in line-level position, the gain for inputs 1 and 2 is controlled by the front panel recessed
potentiometers or by a menu sensitivity setting. When set for front panel control in the user menu,
LINE
INPUT
1:
GAIN
and
LINE
INPUT
2:
GAIN
controls in the user menu are lined out and not acces-
sible.
Input Linking (Stereo or MS Decoding)
Analog inputs 1 and 2 can be linked as a stereo pair. When linked, the channel 1 front panel potenti-
ometer controls the signal level of both inputs, and the channel 2 pot controls the left-to-right balance
of the pair. When the inputs are linked, their peak limiters are linked, as well.
When set to link as an MS pair, the inputs are decoded as MS stereo, where the gain and balance for
the pair work the same as stereo linking above. Input 1 is for Mid signal, input 2 for Side signal.
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