Klark Teknik DN540 Manual Do Utilizador

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Balancing refers to the type of input or output signal connections in an audio system.  
These connections are specifically designed to reject external noise, such as from mains 
wiring and internal interference from adjacent signal cables.  Unlike unbalanced lines, 
which are more susceptible to noise, balancing is especially useful when long cable runs 
are used between pieces of equipment and can also provide other benefits, including an 
increase in line signal level and a decreased possibility of ground loops.  Balanced 
connections are typically employed on long cable runs, such as to amplifiers, or for 
cables carrying sensitive or low level signals, for example, mics.  A balanced line 
typically employs connectors of the XLR and 1/4” TRS jack plug types.

The basic principle of balanced interconnection is the cancelling out of any electrical 
noise by means of a three-cable connection to achieve the required signal.  Two of the 
cables, called “hot” and “cold”, are used to carry signals, and the third is a grounded 
shield that surrounds the hot and cold cables.  (An unbalanced connection only has two 
cables, one of which, the grounded shield, is also used for signal return.)  As the hot 
and cold cables are of equal voltage (and the same source impedance), but of opposite 
polarity, when they are subtracted any noise voltages — caused by interference and 
noise pick-up — appearing identically on both cables is cancelled out; the difference 
between them being the resultant signal.

However, in practice the electrical noise on both cables will never be identical, and the 
degree to which it is reduced is measured by the common mode rejection ratio (CMRR).  
The electronically balanced input and output connections of the DN540 have the benefit 
of high common mode rejection (CMR), which eliminates externally induced 
interference such as mains hum etc.  CMR is the ability of a balanced input to reject the 
part of the incoming signal that has the same amplitude and opposite phase on both 
input terminals, referenced to ground.  As a specification, CMR is usually stated as a dB 
ratio, called CMRR, at a given frequency.