Allen & Heath AP5195 用户手册

28 

PA User Guide 

      ¼”  jack  line  level  outputs  which 

produce 0dBu when the console meters read ‘0’.  With a 
maximum output level of +21dBu there is plenty of headroom 
available.  They are impedance balanced and can be used with 
balanced or unbalanced equipment. 

TRS jack refers to the popular 3-pole stereo ¼” phone 

jack.  It is so called because it has three contacts: tip, ring and 
sleeve.    It  is  used  with  balanced  audio  signals  (tip  hot,  ring 
cold), stereo signals (tip left, ring right), or single jack inserts 
(tip send, ring return).  The 2-pole mono TS jack is used with 
unbalanced signals. 

 

Line level  refers to audio signals in the region of 1 volt.  

For comparison, Mic level refers to very low level signals in the 
order of millivolts, and Speaker level refers to amplifier output 
levels in the order of tens of volts.  Several line level standards 
exist.  These refer to the ‘nominal’ operating level, the point at 
which the meters read ‘0’.  Professional audio equipment 
generally works at 0dBu (0.775V) or +4dBu (1.23V), while 
semi-professional or consumer equipment often works at the 
lower -10dBV (0.31V).  The PA Series has a very wide dynamic 
range making its 0dBu referenced outputs well suited to 
working with these standards. 

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Using line level signals  Use these outputs to feed line 

level equipment such as amplifier, signal processor, recorder 
and IEM transmitter inputs.  Do not connect them directly to 
loudspeakers, or to phantom powered inputs.  Adjust the 
sensitivity of the connected equipment to match the normal 
0dBu operating level of the console. 

Impedance balanced  outputs, like differential electronic 

balanced drivers, use a 3 wire connection to provide the benefit 
of interference rejection when plugged into balanced 
equipment inputs.  The signal is carried on the tip and is 
referenced to ground on the sleeve.  Unlike the electronically 
balanced connection, the ring does not carry signal.  However, 
it  is  held  at  the  same  impedance  as  the  tip  signal  wire.    This 
means that interference is injected equally into both the tip and 
ring wires and cancels out when plugged into a balanced input 
leaving the audio signal unaffected. 

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Using balanced or unbalanced connections    Use 

balanced 2-core plus screen connections when you connect 
the outputs to balanced equipment with cables longer than 10 
meters.  The PA Series outputs work at line voltage and very 
low impedance making unbalanced single core plus screen 
connections suitable for short cable runs as these are seldom 
prone to interference.  To unbalance an XLR output link its pin 
3 (-) to pin 1 (ground).  To reduce interference pickup avoid 
running the cables near to or alongside mains power, lighting 
or computer equipment and cables. 

 

   Use these pre-fade aux sends to drive 

two independent  foldback monitor amplifiers, or transmitters if 
you are using in-ear monitors (IEM). 

   Use this post-fade aux send to drive an external effects 

unit, or for a special feed such as mono recording, audio for 
video feed or additional speaker zone. 

      This  output  follows  the  channel post-fade sends to the 

internal effects unit.  Use it when you are not using the internal 
effects unit, or to feed an external effects unit at the same time 
for layered effects.