Allen&Heath GL2800 - Manual (Page 28)

28 GL2800 User Guide
Polarity Refers to the positive (+) and negative (-) wires of a
loudspeaker or balanced audio connection. The console input
channels include POLARITY switches which reverse the + and – input
connections. Some applications include correcting for reverse wired
cables, correcting for microphone placement problems, mixing two
mics on a snare drum, one above the other below where the
diaphragms move in opposite directions, and helping to reduce comb
filtering effects as radio miked actors perform close to each other.
Polarity is sometimes labelled ‘phase’ on mixing consoles.
Technically, ‘phase’ is not the correct term as it implies a 180 degree
time shift. Polarity simply reverses the wires. It does not affect time.
Before starting your mixing, check that all the channel polarity
switches are correctly set, normally up (+).
Mixing the PA in mono or stereo? Because a console
provides an L and R output does not mean you have to mix in stereo.
It is often convenient to have separate fader control, processor inserts,
and outputs to drive two mono speaker stacks in an FOH system.
How much stereo you introduce into your mix depends on where you
position the pan controls. In most situations the size of the room and
position of the speakers makes stereo mixing an advantage only for a
small section of the audience, usually those around the sound
operator! Those listening near the speakers are likely to lose
information from the opposite stack. For this reason it is best to mix
most sources in mono (pan centred). However, it can enhance the
image by mixing some ‘ambient’ sounds in stereo, for example reverb
returns, keyboards and special effects. Where the speakers are
widely placed, you can reduce the stereo image by reducing the
amount of panning to each side. Whatever image you create it is
important that you listen to the results and consider the listeners at all
positions in the room.
Zero the console Before starting the sound check it is good
practice to ‘zero’ the console by setting all its controls to a sensible
starting condition. Check that the mode switches are correctly set for
your application. Set all GAIN, EQ and PAN controls mid, FADER, AUX
and MATRIX controls off, TALKBACK and OSC/NOISE levels off, and
all switches up. Make sure the osc/noise generator is turned off. Cue
Sheets are provided at the rear of this user guide for you to copy and
log your control settings. This can also be downloaded from our web
site.
Turning the system on and off It is good practice to:
• Turn the amplifiers on last and off first.
• Mute channels before plugging cables, unplugging
instruments and switching phantom power.
• Let equipment which has been stored in a damp or cold
place acclimatise in the venue first before powering it up.
• Power up the system in plenty of time before you start the
sound check or show.
Sound levels The ear is a delicate instrument. Do not subject
yourself or any listener to long periods of loud sound, particularly with
extreme equalisation. This may result in frequency selective or full
range hearing loss. Adhere to the sound level regulations which may
apply to the venue… and common sense!
10
10
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30
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00
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00
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00
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0
00 0 0
0
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0 0
0
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5
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20
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0 0
0
5
5
30
20
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1 2 3 4 5 6 7 8 L R M
POWER
+9
+6
+3
0
-3
-12
-16 -30 -20 -9 -6
+16
+10 2TRK
R
TO LR
2TRK REPLAY
OO
L
1-2 AUX
3-4 AUX
5-8 AUX
9-10 AUX
MTX3-4 MTX1-2
LATCH
L-R
TALKBACK MIC
MAX MIN
MAX MIN
ON
TALKBACK
OSC/NOISE
M
TALK
M
L-R
9-10 MONITOR
2TRK
AUX MTX4
MTX3
MTX2 MTX1
10 0
PFL/AFL MONITOR
STEREO
STEREO
MUTE GROUPS
WEDGE MODE
10
M P/AFL
0 0
1kHz OSC PINK NOISE
PFL
REV REV REV REV REV REV REV REV REV
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
O
= GRP5 TO LR
R L
PAN = GRP6 TO LR
R L
PAN = GRP7 TO LR
R L
PAN = GRP8 TO LR
R L
PAN =
GRP1 TO M GRP2 GRP4 GRP3 GRP5 GRP6 GRP7 GRP8 TO M TO M TO M TO M TO M TO M TO M
MUTE STEREO +10 OO
9-10 AUX 3 AUX
O O
AUX 1
OO +10 AFL AFL +10
2 AUX 0 0
AFL +10 OO AFL +10 OO
0 4 AUX 0
AFL +10 OO
5 AUX 0
AFL +10 OO
6 AUX 0
AFL +10 OO
7 AUX 0
AFL +10 OO
8 AUX
MUTE
LEVEL
R
L
6
7
8
GRP
5
GRP
GRP
2
3
GRP 4
GRP
GRP
GRP
1 GRP
IN EXT
M
MUTE
LEVEL
R
L
6
7
8
GRP
5
GRP
GRP
2
3
GRP 4
GRP
GRP
GRP
1 GRP
IN EXT
M
MUTE
LEVEL
R
L
6
7
8
GRP
5
GRP
GRP
2
3
GRP 4
GRP
GRP
GRP
1 GRP
IN EXT
M
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
O +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
OO +6
MUTE
LEVEL
R
L
6
7
8
GRP
5
GRP
GRP
2
3
GRP
4
GRP
GRP
GRP
1 GRP OO +6 IN EXT
M
DUAL STEREO RETURN DUAL STEREO RETURN
ST4
ST3
MUTE
DIRECT TO LR O O
L-R
3-4
M
O O
+6 9-10 AUX
2 AUX
1 AUX
OO
+6 OO
+6 O O
PFL
ST2
ST1
5 0
10
20
5
OO 30
MUTE
DIRECT TO LR O O
L-R
1-2
M
O O
+6 9-10 AUX
2 AUX
1 AUX
OO
+6 OO
+6 O O
PHONES
STEREO ST2 GAIN -10 -20 10 16
-5 0 5 STEREO GAIN -10 -20 10 16
-5 0 5
STEREO GAIN -10 -20 10 16
-5 0 5 STEREO GAIN -10 -20 10 16
-5 0 5
MUTE MUTE MUTE MUTE MUTE MUTE MUTE MUTE MUTE
SIG 0 +6 PK! SIG 0 +6 PK! SIG 0 +6 PK! SIG 0 +6 PK! SIG 0 +6 PK! SIG 0 +6 PK! SIG 0 +6 PK! SIG 0 +6 PK! SIG 0 +6 PK! SIG 0 +6 PK! SIG 0 +6 PK!
0dB OO
L-R TO M PAN GRP2 GRP1
L
PAN
R
TO LR = PAN
L R
TO LR = GRP4 GRP3 TO LR
R L R
= TO LR
L
PAN
30
O O
5
20
10
0 5
10
GL2800 GL2800
FADERS
ROTARIES AUX MODE FOH
MONITOR
POLARITY
Think before you hit
the switch!