Lectrosonics T187 - Manual (Page 6)

BASS FILTER
In addition to the tone controls, the T187 also has a built in bass filter. This filter is fixed and cannot be adjusted or
defeated. Low frequency noise is much more of a problem with wireless microphones than with conventional micro­
phones. With a regular mic, low frequency wind noise, breath thumps or handling rumble can be filtered out at the
control board before the noise causes problems with the following electronics or speaker systems. But with a
wireless microphone, the electronics that will be overdriven are right in the wireless microphone. Filtering at the
control board is much too late. To solve this problem, the VariMic has a low frequency filter that is so sharp that it
can remove low frequency noise without affecting any wanted vocals. It consists of a 36 dB per octave filter circuit to
sharply remove low frequency noise below 75 Hz without affecting vocal fundamentals. The lowest operatic bass
voice fundamental is 82 Hz. See the curve below.
T187 Bass Filter
20
0dB
-20
-40
-60
ATTENUATOR
The VariMic head includes an attenuator to provide an additional 15dB of
-3dB @ 71Hz
-20dB @ 50Hz
10Hz 100Hz 1KHz 10KHz
headroom when needed. The attenuator should only be used when the normal
Mic Level pot is already turned down as far as it will go and the signal through
the mic is still too hot. The attenuator control is a 16-position switch marked 0
through F. “F” is minimum attenuation or the highest signal level. “0” is maxi­
mum attenuation or the lowest signal level. For the maximum amount of head­
room, set the switch to “0.”
Note: The attenuator should not be used as a level control. The Audio
Level control inside the battery compartment is the main level control.
Adjust the attenuator only when the Audio Level control is turned
completely down and more headroom is still needed. Be sure to set the
attenuator back to its original setting for normal operation.
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