Allen&Heath DR66 USER GUIDE - Manual (Page 21)

DR66 & DR128 Installer User Guide 21
Calibrating Mic/Line Input Gain
DR66 Adjust the internal calibration trimmer to set the input gain to match the connected source.
DR128 Use a small flat bladed screwdriver to adjust the recessed rear panel gain trimmer.
It is necessary to assign the front panel LED indicators as input signal meters before setting gain.
The default configuration loaded into the DR when shipped does this. Alternatively, connect a PC
and use the WinDR System Manager application to view the signal meters.
Set the gain so that normal signal level lights the green signal meter LED with the loudest
moments changing to amber. Increase the trimmer until the very loudest moments start to flash
red indicating that you are within 6dB of clipping. Back the trimmer off slightly so that the red LED
does not light. To avoid distortion the signal level should not be allowed to reach the 0dBFS
maximum.
RCA Phono Line Input Connections
Line sources such as CD players, tape machines,
video players and satellite receivers can be plugged
into these inputs. Each of the 4 channels provides
two connectors A and B which allow two mono
sources to be combined or a stereo source to be
summed into mono. Zoned sound installations
typically require stereo sources to be converted to
mono. However, stereo zoning can be achieved if
required by plugging the left and right signals into
different channels.
Calibrating Line Input Gain
DR66 Set the internal jumper link in the –10dBV position for low level sources, or in the +4dBu
position for high level sources. DR128 Adjust the internal trimmer by carefully inserting a small flat
bladed screwdriver through the access hole shown, locating it in the trimmer slot and rotating it to
set the input sensitivity over its 12dB range to match the source. Adjust from +4dBu to –8dBu (-
10dBV). Do not use excessive force.