Crest Audio XRM - 12 - Manual (Page 19)

Front panel features
The XRM features four, full-function Stereo Input channels.These inputs are labeled S1 thru S4 and are located
directly left
of the master section. Each stereo channel features two mic preamps, so mic-level stereo sources
can be processed on one common channel. In cases where just a mono source is present, the SUM INPUTS
switch allows a mono source (plugged into either left or right input) to feed both sides of the stereo chan-
nel, effectively turning the stereo channel into an additional mono channel for the mixer.This SUM INPUTS
switch also permits the operator to collapse a stereo signal to mono if necessary.
The Stereo channels are very similar, front-panel wise, to the Mono channels. In most cases, the controls will
be identical and the descriptions are repeated here.Any Stereo-specific or Stereo-different controls will be
identified as such and further described.The rear panel differs in the amount of jacks offered per channel.
Because of space limitations, there is no Channel Insert jack available on the Stereo Channels.
Str Line In (Mic Pad)
With this switch in the UP position, the input preamp circuits are set up to accept mic-level
signals. These signals are brought in via the XLR mic-input connectors located on the rear panel.
The 1/4" TRS input jacks are ignored.
When the switch is depressed, a Pad is inserted into each of the signal paths and the input
preamp circuits are capable of accepting line-level signals from either the XLR mic-input connec-
tors or the 1/4" TRS input jacks, located on the rear panel.The XLR signal is normal'd to the 1/4”
TRS jack. If nothing is plugged into the TRS jack, the XLR signal is fed to the preamp when the
LINE switch is pressed. Since the TRS signal is always padded down by 26dB, this feature allows
the LINE switch to act as a PAD switch for bringing a very hot microphone signals down to a
controllable level, avoiding overload.When a plug is inserted into a 1/4" TRS input jack, the XLR
mic-input signal is disconnected and the signal present on the 1/4” plug is fed to the preamp. If
plugs are inserted into both the XLR and TRS jacks, this switch acts as an input selector switch
between the two jacks.
Gain
The Input gain control is used to establish proper gain structure in the channel. For best
results, use the Solo system to monitor the channel while you set the gain.The goal is maximum
gain without distortion. Both the main LED meters (during Solo) and the channel’s Level/Peak
indicator can be used for adjusting gain.
SUM INPUTS (Stereo-specific)
By summing the inputs, a stereo input channel can be used as a mono input channel.
The channel functions as a stereo input; left input signals feed the left side of the Stereo
channel, right inputs feed the right side.
If signals are applied to both the Left and Right input jacks, they will be summed together as
a mono signal and fed to both sides of the Stereo channel.This sum-point is directly after the
input preamps. If a signal is applied to just one of the input jacks and this switch is pressed, that
lone signal will feed both sides of the channel and it will be treated as a mono signal throughout
the mixer.
Stereo Input channel
2
p. 19