Brauner Microphones VMA - Manual (Page 10)

The ground lift switch detaches the ground pin (pin 1) of the XLR output from ground
and can be set to three positions. Safety earth is never detached of course. Use the
switch to eliminate hum problems you might have.
Lower position: (H)ard-ground: The ground pin is conductively connected to the
ground center of the internal circuit.
Mid position: Ground-(L)ift: The ground pin is completely disconnected from ground.
Upper position: (S)oft-Ground: The ground pin is connected to the ground via a safety
capacitor that decouples the AC portion of the hum to the ground.
Instead of the 10 dB pad switch the VMA has a mode switch to choose between the
two microphone circuits and their tonal characters. In the lower position the VMA is
set to a VM1 sound (natural and transparent), in the upper position to a VMX sound
(soft top end, pronounced mid range and bottom end).
Combining these two tonal characters into one microphone was a technical challen-
ge which our engineers achieved by integrating two complete high quality signal
paths and not by simply using frequency response correction. This opens up the VMA
to a wide variety of applications.
Even though you will hear a sound directly after changing the mode on the VMA, you
should wait a couple of minutes before using the microphone again as the operating
points of the circuitry need some time to bias to the new setting.
On the back panel of the power supply there are three connectors: power, micro-
phone (Tuchel connector) and signal out (XLR phase signal on pin 2). Additionally
there are two switches – power and ground lift – and the voltage setting/fuse holder.
3.2 10dB-Pad (VM1/VMX only)
The 10 dB pad allows you to dampen the microphone‘s sensitivity by 10 dB in order
to handle a higher possible sound pressure level before the impedance converters
start to distort. As the microphone is capable of handling a sound pressure level of
up to 140 dB without any significant distortion or the typical compression artefacts
tube microphones usually show, you will probably need this switch only on very rare
occasions.
3.3 Mode Switch (VMA only)
3.4 Power Supply Back Panel
3.5 Ground Lift Switch
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