User guide

VTX Series User Manual v1.08
The three switches on the rear of VTX ampliers allow a total of 8 routing possibilities, including 4-channel, dual stereo and
mono operation with 4 channels paralleled. The table below claries the options:
AMPLIFIER
CONFIGURATION
BUTTON POSITION
INPUT ROUTING:
AMPLIFIER CHANNELS FED BY EACH INPUT
CH 2 CH 3 CH 4 IN 1 IN 2 IN 3 IN 4
4-channel IN IN IN CH 1 CH 2 CH 3 CH 4
Dual mono + stereo OUT IN IN CHS 1 & 2 CH 3 CH 4
Dual mono + stereo IN OUT IN CHS 1 & 3 CH 2 CH 4
Treble mono + 1 OUT OUT IN CHS 1, 2 & 3 CH 4
Dual mono + stereo IN IN OUT CH 1 CHS 2 & 4 CH 3
Treble mono + 1 OUT IN OUT CHS 1, 2 & 4 CH 3
Dual stereo IN OUT OUT CHS 1 & 3 CHS 2 & 4
Quad mono OUT OUT OUT CHS 1, 2, 3 & 4
Remote Control of Level
VTX ampliers are compatible with standard Cloud remote
control plates Type RL-1, allowing control of level from a
remote position. RL-1s may be connected at the rear 3-pin,
5 mm-pitch screw terminal connectors (REMOTE LEVEL),
using the wiring shown below.
Use two-core screened cable to connect the remote level
plate (maximum length 100 metres).
High Pass Filters
Each channel of the VTX is tted with a switchable hi-pass
lter, which may be switched in as required to reject low-
frequency signals below 65 Hz. The lter has a slope of
18 dB/octave, to provide a high degree of low frequency
rejection.
The primary purpose of the lter is to avoid loudspeaker
transformer saturation when driving 100 V/70 V-line speaker
systems. (The VTX ampliers’ outputs are designed to drive
low-impedances only, so an external transformer will be
necessary for amplier channels to drive such systems. The
Cloud CXL-100T is suitable for use with the VTX4120;
transformers with higher ratings will be necessary for use
with the VTX4240 and VTX4400). Transformer saturation
creates unpleasant distortion and stresses the system, and
the high pass lter should always be switched in when
driving 100 V/70 V-line systems.
Use of the lter with low-impedance loudspeaker systems
is optional and at the discretion of the installer; switching
it in may help to enhance the clarity of speech, reduce
microphone handling noise and breath blasts.
Outputs
The VTX ampliers’ speaker output connections are on
two adjacent 4-pin, 5 mm-pitch screw-terminal connectors
(mating connectors are supplied).
CH 1CH 2CH 1
CH 3CH 4
-+-+-+-+
Each channel’s output stage is designed to drive into an
impedance of not less than 4 ohms. Check the impedance of
the loudspeaker(s) in use and, taking into account any series
and/or parallel wiring, ensure that the total load on each
channel is not less than 4 ohms.
g.6: Output Wiring
g.5: RL-1 Wiring
1
2
3
REMOTE MUSIC
CONTROL
CONNECTOR
1
2
3
RL-1
USE TWO-CORE SCREENED CABLE