8.4.1
Using A Microphone
A microphone is a device which converts sound waves to electrical impulses. High quality
microphones usually generate a very low signal level. Low noise, high fidelity pre-amplification is
required to boost the output of a microphone before the signal reaches the main audio amplifier where
it is processed as a regular audio signal. Pre-amplifying low level microphone signals is achieved by
precise matching of microphone impedance and use of low noise electronic amplifying devices. In
order to obtain the highest quality output signal from a microphone, its internal impedance should be
matched to that of a pre-amplifier with exactly the same input impedance. Microphone impedance
may vary from a few ohms to several mega-ohms.
When a
microphone is used/not used, perform the following steps:
1. Press the
Mic/Line
pushbutton located at the front of the machine, to switch to “
Mic”
position.
This is done in order to compensate for microphone low input level.
2. Release
Mic/Line
pushbutton (no microphone) in normal operation (“
Line
” position).
8.5 Programming The VM-1110 and VM-1610
The mode of operation (programming) is selected by activating one of the
1:10, 2x1:5,
operating
mode switches. These programming switches illuminate as the selection is made and function as
follows:
1:10
position - splits channel "
1
" Input (VM-1610) or input "
A
" (VM-1110) to all 10 outputs.
2x1:5
position - splits channel "
1
" and channel "
2
" inputs " to outputs "
1-5
" of channels "
1
" and
"
2
" respectively (VM-1610). Or: Splits input "
A
" and input "
B
" " to outputs "
1A-5A
" and "
1B-
5B
" respectively (VM-1110).
1. Connect a balanced audio source to the input sockets located on the rear panel of the machine,
using the appropriate cables and connectors and noting the correct polarity (+/-) of the input
signal.
2. Connect up to 10 acceptors to the output sockets, using the appropriate cables and connectors.
3. Operate source, acceptors and the VM-1110/1610.
4. Use the
1:10, 2x1:5
, operating mode switches to select the desired mode of operation.
5. When in stereo mode, connect each channel to the appropriate inputs and outputs and select
2x1:5
mode of operation.
8.6 Programming The VM-80A
The VM-80A mode of operation can be selected by pressing one of the
1:8, 2x1:4
operating mode
switches. These programming switches illuminate as the selection is made and function as follows:
1:8
position
-
splits channel "
1
" input to all 8 outputs (channels "
1
"&"
2
") when pressed.
2x1:4
position
-
splits channels "
1
"&"
2
" inputs to output channels "
1
"&"
2
" respectively when
pressed.
1. Connect a balanced stereo audio source to the terminal blocks located on the rear panel of the
machine, using the appropriate cables and connectors and noting the correct polarity (+/-) of the
input signal.
2. Connect up to 8 acceptors to the output sockets, using the appropriate cables and connectors and
noting the correct polarity.
3. Operate source, acceptors and the VM-80A.
4. Use the
1:8
or the
2x1:4
operating mode switches to select the desired mode of operation.
8.7 Audio System Setup
In broadcast and in high quality industrial studios, audio signals are of the balanced type. In order to
distribute balanced audio signals, a balanced audio source is needed. Figure 5 illustrates a typical
usage of a balanced audio amplifier.
Perform the following steps if necessary):
1. Connect the audio source to the balanced audio DA (VM-5AD for example).
2. Connect the audio acceptors to the output sockets of the balanced DA.
3. Use the controls of the DA (if available) to adjust signal levels (see sections 8.3 and 8.4 for more
details).
