Z4
II
& Z8
II
Installation and User Manual v1.0
25
PSU capability and optional
device current consumption
In addition to supplying the Zone Mixer’s circuitry, the
internal PSU has the capacity to power some additional
items which may form part of a complete system. These
include LM-1 and DM-1 active remote input plates (via the
Facility Port), Bose® EQ cards (fitted internally), and possibly
a PM Series paging microphone (powered via the Access
Port).
The maximum current capacity of the PSU available for
powering external items is 120 mA (Z4
II
) or 190 mA (Z8
II
).
Current consumption of the various items is listed in the
table below.
ITEM
CURRENT PER UNIT
DM-1 dual mic input plate
18 mA
LM-1 mic/line input plate
12 mA
PM-4 or PM-8 paging
microphones
40 mA
Bose® EQ for MA12, 402-II,
502B, 502BEX
12 mA
Bose® EQ for 3302, 4402,
9402, 9702
17 mA
The installer should ensure that the total current drawn by
all the external items in a system does not exceed 120 mA
(Z4
II
) or 190 mA (Z8
II
).
Note that PSU performance will be degraded at ambient
temperatures in excess of 35°C.
Ground loops
If, despite your best efforts, the completed sound system
‘hums’, you probably have a ‘ground loop’. The offending
signal source can often be identified by setting the volume
control to minimum. then disconnecting the input leads
(both left & right channels) on each line input until the ‘hum’
disappears. This problem is often caused by terminating
a screened input cable into a signal source positioned a
significant distance from the mixer. A good way of avoiding
this potential problem is to use signal sources (CD players
and the like) that are double insulated with no connection
to the mains supply earth. If a signal feed were derived from
a second mixer (a club or microphone mixer for example) it
would be perfectly normal to expect this to be earthed; we
suggest that a transformer be used to isolate the signal and
prevent a noisy loop (see page 10 -
Music Sources
).
EMC considerations
The Cloud Z4
II
& Z8
II
fully conform to the relevant
electromagnetic compatibility (EMC) standards and
are technically well behaved; you should experience no
operational problems 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 communications transmitters, radar
stations and the like, the performance of the mixer may be
reduced; we suggest that the microphone cable screen be
connected to the shell of the XLR type connector and the
line input leads are kept as short as possible.
