Microplane 201 - Manual (Page 3)

Thank you for purchasing the Grace design model 201 microphone preamplifier. It is built to
be completely reliable and easy to use. However, there are some important instructions
included in this manual. Please take the time to familiarize yourself with the installation and
operation of the unit and most problems will be avoided. Regardless of what sources you
plan to record, the model 201 will be the invisible link between the microphone and
recorder. Grace Design has been building professional audio products for the recording
industry for over ten years. During this time the model 201 has evolved through a process
of extensive listening, testing and refinement. We hope it helps you achieve a new level of
excellence.
I. OPERATION
A. FRONT PANEL CONTROLS
Figure 5. FRONT PANEL CONTROLS
1. GAIN CONTROL Each gain control has 24 positions and adjusts the voltage
gain from 18dB to 64dB in 2dB steps. For reference, the 9 o'clock position is
30dB, the 12 o'clock position is 42dB, and the 3 o'clock position is 56dB.
2. TRIM CONTROL The trim control provides 10dB of continuously variable output
attenuation. In the fully clockwise position the trim is at unity (no attenuation). In
the fully counter-clockwise position the trim is at -10dB. For reference, the 3
o'clock position is -4dB and the 12 o'clock position is -8dB. The trim control
should be left in the fully clockwise position during normal recording.
3. PHANTOM POWER The phantom power switch (labeled 48V) connects the
+48V power supply to pins 2 and 3 on the XLR input connector. This switch
illuminates red. It should be noted that the LED in this switch actually monitors
the voltage at the input. With no microphone connected, the LED will continue to
illuminate for approximately 10 seconds after the phantom power is turned off as
the filter capacitors discharge. As well, even if the phantom power is switched
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