Allen & Heath AP5195 用户手册

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PA User Guide 
19 
 
EQUALISER 
  The stereo equaliser allows independent 
adjustment of the low and high frequency bands. 
HF
  The high frequency band has a shelving response that 
cuts or boosts the higher (treble) frequencies by up to 15dB.  It 
has most effect from 12kHz and higher. 
LF
  The low frequency band has a shelving response that cuts 
or boosts the lower (bass) frequencies by up to  15dB.   It has 
most effect from 60Hz and lower. 
   
The EQUALISER  is based on the classic Baxendall 
design  similar  to  that  found  in  audiophile hifi systems.  Its 
shelving response has an increasing effect as it approaches 
the low and high frequency extremes. 
    Using the equaliser      It  is best  to  keep  the  adjustments 
made using the equaliser as small as possible.  Avoid the 
temptation to excessively boost the low and high ends to 
compensate for poor speaker frequency response.  This simply 
overworks the amplifiers with little audible improvement from 
the speakers.  Using cut rather than boost is often more 
effective in improving the clarity of the signal.  For example, use 
HF cut to quieten a hissy keyboard, some LF and HF cut to 
shape a reverb return, and LF to cut back low frequency hum 
or resonance.  On the other hand, a small amount of HF boost 
can brighten up a dull recording, or add some ‘air’ to keyboard 
string sounds. 
 
AUX SENDS 
  The stereo channel aux sends function in 
the same way as described previously for the mono channels.  
Note that the L and R signals are summed together to produce 
a mono send for each of the four auxes. 
BAL 
  Adjusts the level balance between the L and R signals.  
At its extreme ends one signal is fully off, the other fully on.  
The control has a 3dB attenuation at its centre position to 
ensure equal total power as the balance is adjusted. 
MUTE, PFL, PK! And FADER 
    Function  in  the 
same way as described previously for the mono channel.  Note 
that the stereo signal is summed to produce a mono PFL feed.  
The PK! Indicator senses the higher of the L and R signal 
levels.  The fader controls the L and R signals together. 
  To avoid loud clicks or unexpected noises always 
mute the channel before plugging or unplugging the inputs.  
Use PFL to set the channel gain before raising the channel 
fader and sends.
 
10k
1kHz
100
30k
10
LF
HF
STEREO EQ
-15
-20
-10
-5
0dB
+5
+10
+15
+20
+15
-15
60Hz
12kHz
+6
+15
+6
+6
O
-15
O
O
O
O
O
=
+6
R
O
L
O
PK !