VLC Microphone Preamplifier/EQ/DI
HAZELRIGG INDUSTRIES
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conjunction with or as a substitute for the VLC pad should be determined by experimentation. For
the cleanest sound it is generally preferable to pad at the microphone first, then at the VLC if
necessary. The sound of some microphones will change slightly with the -20 position. This is a
function of the interaction between the microphone transformer and the VLC input transformer.
POL (6)
This switch reverses the polarity of the output of the VLC.
Even when there is only one microphone being recorded, it may be useful to try the up position of
the polarity control. Although there is supposed to be standardization in polarity throughout the
professional audio equipment industry, it is possible that a wiring error or the use of vintage
equipment built before standardization may reverse the polarity in the recording/monitoring
chain. The effect of reversed absolute polarity is usually subtle, but can be significant with some
sounds. If the reverse position sounds better, use it.
With more than one microphone on the same sound source (or picking up leakage from another
sound source), the POL switch may have a profound effect on the audio quality. Whichever
position sounds best is correct. A check of monaural compatibility (by summing the various mics)
should also be performed.
EQ In (7)
This engages the equalizer into the audio path. When the EQ is not engaged the audio goes
through a pad that mimics the overall audio loss of the EQ.
Output Signal Indicator (8)
The bi-color LED (8) displays output directly from the secondary of the output transformer,
through an isolation amplifier. Ideally, the indicator should show green while re-recording signal.
The LED is calibrated to turn red when nearing the upper input level of most digital audio
convertors.