GAIN control for input channels. This allows the sensitivity (input gain) for every line input to be
adjusted, so that sources of different output level can be played at properly balanced levels.
Microphone inputs. This are balanced ¼” TRS connectors, which can be internally set to either
carry phantom power (+12V DC) or not, thus this input can be used both with condenser and
dynamic microphones (see chapter “setup configuration”, jumper JP102, JP104, JP106 -
default is phantom power = OFF).
GAIN control for microphone inputs. These controls allows the sensitivity (input gain) for the
input to be adjusted to the microphones in use.
Low impedance speaker output. This is a 2-pin 5 mm-pitch screw terminal connector. The
internal amplifier is able to deliver its rated power into a 4 ohm load, with the maximum output
power reduced with higher load impedances. When using multiple low-impedance loudspeak-
ers (normally 8 ohms) with a single amplifier, series and/or parallel wiring should be employed
to produce a total load impedance of not less than 4 ohms. Note that one of the output pins is
connected internally to 0 V. Note that this output can NOT be used at the same time as the
LINE level speaker output (15). To avoid simultaneous use, the unit has to be internally config-
ured for either Low impedance or Line level operation. As a factory default, this Low Imped-
ance output is active, and the Line level output (15) is disabled.
Line level (Constant Voltage / High impedance) output. This amplifier is fitted as standard with
an output transformer that can be enabled by moving an internal connector (see chapter
“setup configuration”). The transformer should be placed in circuit if the amplifier is to be used
with a 100 V, 70 V or 25 V line speaker distribution system. Once the output transformer is
enabled, make sure that the provided safety cover is fitted over the connector (15), which may
have been removed to connect the speaker cable. Note that the transformer secondary has
3 line outputs: 100 V, 70 V and 25 V; whilst these have a common 0 V connection, the output
is fully floating i.e. it is isolated from the rest of the amplifier. When the transformer is in use
the maximum total combined load should not exceed the rated power of the amplifier. Note
that this output can NOT be used at the same time as the Low impedance speaker output
(14). To avoid simultaneous use, the unit has to be internally configured for either Low imped-
ance or Line level operation. As a factory default, this Low Impedance output is active, and the
Line level output (15) is disabled. Once this Line level output (15) is enable, the Low impedance
output (14) will be disabled.
Fan cover. For extended reliability under full rated power, this amplifier has an internal cooling
fan. Make sure to not obstruct the fan vent, and also keep the fan inlet on the front panel clear.
Microphone volume controls. These rotary controls adjust the volume of the microphones
connected to the inputs (12).
Microphone On-Off switches. Enable the relative microphone when being pressed, and disable
the microphone when being released. A LED indicates enables status.
Microphone Equalizer. Allows the adjustment of the tonal balance for all three microphone
input together in two voice-specific frequency bands with an adjustment range of ±10dB.
TALKOVER On/Off switch. Engages or disengages the talkover function, which allows to
reduce the music level automatically when the microphone is spoken into (also called priority).
The amount of damping applied to the music signal is controlled by the damping control (21).
Talkover Damping Control. Provided the talkover on/off switch (20) is set to ON, this control
determines the amount of damping applied to the program signal when the microphone is
spoken into. Fully turned clockwise, maximum attenuation is applied, being turned fully
counter-clockwise, the damping is negligible.
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USER MANUAL - VMA1120 INSTALLATION MIXING AMPLIFIER