Control Elements; Preamplifier; Mic Gain, 48 V, Activating Phantom Power, Phase Reverse - SPL Channel One 2950 Manual

Preamplifier

MIC GAIN
The MIC GAIN control determines the level of preamplification. The preamplification values
cover a range from +8 dB up to + 68 dB. Further information on page 12, „GAIN adjustments". If
the optional microphone input transformer is installed, the scaled values are to be increased
by ca. +14 dB (depends upon microphone, see page 29, "Information on I/O transformers").
48 V
The 48 V switch activates phantom power for condenser microphones with built-in ampli-
fiers. Phantom power should only be activated when using microphones that require it.
VERY IMPORTANT: All microphones with balanced, ground-free outputs, can be used with
the phantom power activated. Please be sure to deactivate phantom power with all other
microphones. Unbalanced microphones may only be used with phantom power deactivated.
Activating phantom power
PLEASE ALWAYS FOLLOW THESE INSTRUCTIONS TO ACTIVATE AND DEACTIVATE PHANTOM
POWER (ALSO WHEN CHANGING MICROPHONES). THE INPUT STAGE OF THE CHANNEL ONE
CAN BE DAMAGED IF YOU IGNORE THESE PROCEDURES!
1. Connect the microphone to the Channel One.
2. Now activate phantom power to use the microphone.
3. After recording first deactivate phantom power.
4. Wait at least one minute after deactivation of phantom power before disconnecting the
microphone! This ensures residual current will be discharged.
Phase reverse
The phase reverse function reverses the polarity of the microphone signal, inverting the
phase (by 180°) to correct phase-inverted signals caused by multiple signal sources. A voice-
over artist, for example, hears himself through the headphones and simultaneously through
the bones in his head. Phase inversion will cause an unnatural sound, and even minimal
variations in distance to the microphone will cause drastic variations in the sound. Phase
inversion is also commonly encountered when using multiple microphones on a single sound
source. We recommend checking for correct polarity before recording.
Channel One

Control Elements

11