Boundary Microphone
ACBMIC
The ACBMIC is a directional electret boundary layer microphone. It is designed to
be connected to unbalanced microphone inputs with bias powering such as those
found on the Ampetronic ILD100 and CLD1 induction loop amplifiers. The unit is
directional when properly mounted, so it can reduce unwanted sound pickup from
sources that are not in front of the microphone.
Restrictions on usage
The ACBMIC should not be directly connected to balanced or line level inputs. It
should only be connected to inputs intended for unbalanced electret microphones
with DC bias power.
1. Mounting
Boundary layer microphones are intended for
mounting on a surface. The surface forms a
part of the pickup pattern of the microphone.
The surface should not be subject to strong
vibration as this can be picked up by the
microphone.
The microphone should be placed so that it
points towards the wanted sound source (e.g. The receptionist at a counter) and is
reasonably close to that source. Take care to ensure that the microphone does not
pick up unwanted sounds when choosing where to put the unit.
2. Output connection
The ACBMIC is terminated in a 3.5mm mono jack plug. This should be plugged into
the microphone input of the ILD100 or CLD1. To connect the ACBMIC to a balanced
microphone input, the Ampetronic MAT1 adapter should be used with phantom
power on the amplifier.
Any extension up to 3 metres total cable length should be made using a screened
cable and good quality connectors. Under no circumstances should the output
cable be extended beyond a total length of 3m as the extended connection would be
susceptible to interference. Using an Ampetronic MAT1, output cable length can be
extended using balanced cables.
