Cloud Electronics VTX4400 - Manual (Page 10)

VTX Series User Manual v1.0 10
Bose® equalisation modules
(optional)
VTX amplifiers are compatible with Bose® Series II
loudspeakers; a single-channel Bose® equalisation module
may be fitted to as many channels as necessary. Equalisation
modules for the following Bose® models are available:
• Panaray MA12
• Panaray 402-II, 502B and 502BEX
• Panaray LT Series: Models 3302, 4402, 9402 and 9702
Other modules are available to provide the correct
equalisation for loudspeakers from other manufacturers as
well as for other Bose® models; please contact Cloud for
more details.
Installation
• With the power turned off and the mains cable
removed, remove the top panel.
• Refer to the PCB layout diagrams at fig.9 on page 12.
The modules plug into the white 12-pin connectors
(J104 to J404) on the upper PCB adjacent to the rear
panel. Note the header connectors on the PCB have
two notches on one side only; these engage with lugs on
the equalisation module’s mating connector to ensure
correct orientation.
• After fitting equalisation modules to any channel(s), the
corresponding module bypass jumper(s) (J108 to J408)
must be removed in order for the module to function.
Refer to the PCB layout diagrams for full details.
• Replace the top cover with the original screws after
fitting.
General Notes
EMC Considerations
Cloud VTX amplifiers fully conform to the relevant
electromagnetic compatibility (EMC) standards and are
technically well behaved. You should experience no problems
interfacing units to other items of equipment and under
normal circumstances, no special precautions need to
be taken. If the unit is to be used in close proximity to
potential sources of HF disturbance such as high power
communication transmitters, radar stations and the like,
it is suggested that input signal leads be kept as short as
possible. Always use balanced interconnections wherever
possible.
Earthing
When several mains powered units are connected together
via their signal cables, there is a risk of one or more earth
loops which may cause an audible hum on the system even
with the gain controls set to minimum. The 0 V rail of a
VTX amplifier is directly coupled to the chassis ground. No
interconnection problems should be encountered, but if
there is any hum or other extraneous noise when source
equipment is connected, the situation can generally be
remedied by observing the following guidelines:
• Always connect sources using balanced connections
wherever possible, with the cable screen only connected
at the receiving end (amplifier input).
• Use audio isolating transformers (readily available from
trade suppliers) at the inputs if necessary. These will
ensure that the amplifier is electrically isolated from the
source equipment.
The signal source units should be located as close as
possible to the amplifiers and the metal housing of the
various units should not be electrically connected together
through the equipment rack. If this is a problem, rack
isolating kits are available from specialist hardware suppliers.
If the problem persists, try to connect all interconnected
units, including power amplifiers, to a common power source
to ensure a common ground is provided.