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When sending a signal to a recorder, converter or interface that has fixed input levels,
simply increase the gain until the optimum recording level is reached. If the peak in-
dicator flashes red excessively with the gain control in the fully counterclockwise posi-
tion, engage the -20dB attenuator.
When sending a signal to a tape recorder with an input attenuator (i.e. the record level
control on a DAT or CDR recorder) use the following procedure: With the sound source
present, turn the gain control clockwise until the peak LED begins flashing red, then
reduce the gain until the red stops flashing. Since red indicates a peak level which is
12dB before preamplifier clipping (6dB in unbalanced mode), it is OK for it to come on
periodically during recording. If peak indicator flashes red excessively with the gain
control in the fully counterclockwise position, engage the -20dB attenuator. Now ad-
just the recorder input control for the optimum recording level.
RIBBON MIC MODE
Pressing the ribbon switch optimizes the m801 channel for ribbon microphones by
boosting the gain by 10dB while disabling 48V phantom power. Before activating rib-
bon mic mode, make sure the channel's gain is fully down (counter-clockwise) and 48V
phantom power is off. Now simply press the ribbon switch and turn the gain control
upwards until the proper recording level is achieved.
If you press the 48V phantom switch while the ribbon switch is engaged, nothing will
happen. However, if the 48V phamtom switch remains depressed and the ribbon mic
switch becomes inadvertantly disengaged, 48V phantom will consequently be acti-
vated, which can potentially harm a ribbon your microphone if it is still connected to
the input. If the 48V phantom power switch is turned of and then the ribbon switch is
turned on the preamplifier will wait until the phantom power voltage has completely
discharged and then the ribbon mode will activate automatically. An additional ben-
efit of the ribbon mic mode is that the input DC blocking capacitors are relay bypassed
to further simplify the m801's signal path. Incidentally, the ribbon mode works very
well with many lower output dynamic microphones as well as ribbon types.
Maintenance
The model m801 was designed to be maintenance free for many years. It is highly
unlikely that your unit will require service. However, there are two adjustments that
may need to be made from time to time. These procedures should be made only by a
qualified service technician or the Grace Design factory.
PEAK LED ADJUSTMENT PROCEDURE
The peak LED threshold levels may be adjusted to a user defined operating level. This
circuit is set at the factory with the green threshold at -14dBu and the red threshold
grace design m801
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owner's manual
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