grace design m201
mk2
owner’s manual
7
before preamplifier clipping, 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 adjust the recorder input control for the optimum recording level.
RIBBON MIC MODE
Pressing the ribbon switch optimizes the m201mk2 channel for ribbon microphones by boosting
the gain by 10dB while disabling 48V phantom power and increasing the input impedance. Before
activating ribbon 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. If the
48V phantom power switch is turned off 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 benefit of the ribbon mic mode is that the input DC blocking
capacitors are relay bypassed to further simplify the m201mk2’s signal path. Incidentally, the ribbon
mode works very well with lower output dynamic microphones as well.
It is not recommended to use Ribbon Mode and the -20dB pad at the same time. This will cause the
microphone to see a variable input impedance and will cause a low frequency response bump of up
to 10dB depending on the microphone output impedance.
Maintenance
The model m201mk2 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
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 -16dBu and the red threshold at +16dBu. The relationship
between the two thresholds is fixed. The procedure for adjusting the greed / red threshold follows:
EQUIPMENT NEEDED
•
Sine wave audio signal generator or oscillator output from a mixing console.
•
Audio level meter, RMS volt meter with dBu or dBm scale, or digital volt meter (DVM) with AC
RMS measurement.
•
Plastic alignment tool or small screwdriver
•
Appropriate interconnect cables
•
#2 phillips head screwdriver
PROCEDURE
