46/50 Integrated Mixer Amplifier
Setup And Installation Guide
CLOUD ELECTRONICS LIMITED
17 Solving problems
17.1 Ground loops (aka Earth loops)
Despite your best efforts, if the completed sound system 'hums' you probably have a 'ground
loop'; the offending signal source can be found 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 46/50.
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 is derived
from a second device (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 diagrams below).
17.2 Connecting balanced signals to unbalanced line
inputs.
We recommend the use of a transformer to convert a balanced signal to an unbalanced signal
suitable for direct connection to the 46/50 line inputs. The transformer should be mounted close
to the 46/50 and the unbalanced output lead should be kept as short as possible. Where both
the source and destination units are earthed, it is important to isolate the primary and secondary
windings to avoid a potential ground loop; if there is any doubt about this, we suggest that the
balanced cable screen is not connected at the transformer end. RS Components part 210-6447
is a suitable transformer for this application we recommend that the screening can (part number
210-6469) also be fitted to the transformer; Canford Audio supplies a similar transformer (part
number OEP Z1604). All transformers should be wired to give a ratio of 1:1.
17
V6 070113
SINGLE SCREEN
CABLE
SINGLE SCREEN
CABLE
HOT
SCREEN
HOT
SCREEN
HOT
SCREEN
HOT
COLD
TWO-CORE
SCREENED
CABLE
(SCREEN NOT CONNECTED
AT THIS END)
HOT
HOT
COLD
TWO-CORE
SCREENED
CABLE
TWO-CORE
SCREENED
CABLE
(SCREEN NOT CONNECTED
AT THIS END)
SINGLE SCREEN
CABLE
COLD
SCREEN
CONVERTING UNBALANCED
TO BALANCED USING A
1:1 RATIO TRANSFORMER
CONVERTING TWO PIECES
OF UNBALANCED EQUIPMENT
USING A 1:1 RATIO TRANSFORMER
CONNECTING TWO PIECES OF
BALANCED EQUIPMENT USING A
1:1 RATIO TRANSFORMER
Summary of Contents for 46 INTEGRATED
Page 24: ...Notes...
