4
QA4150 / QA4300
Front Panel Controls
1. Rack Mounting Ears
Two front panel mounting holes are pro-
vided on each mounting ear.
2. Fan Vent
QA series amplifiers are cooled by two
rear-mounted fans. Cool air is flowed through
the front fan filters, reducing the temperature
of the inside components while forcing the
heat out the rear vents. Never block these
vents and keep them clean at all time.
3. AC Power Switch
This switch controls the units main power.
4. Signal Indicators
These green and yellow LED will illumi-
nate to indicate that a signal is present at the
amplifier input, and that the signal is being
amplified.
5. Clip Indicators
These red LED will illuminate at the clip-
ping threshold. If it lights frequently, you
maybe overloading the QA Series and a dis-
torted signal is probably being output. Under
heavy clipping activity lower the channel gain
controls to reduce the risk of damage to your
speakers and amplifier.
6. Power Indicators
These blue LED indicate that AC power is
connected and the amplifier is turned on.
POWER AMPLIFIER
QUAD-CHANNEL
POWER
ON
OFF
QA4300
HPA
CHANNEL 1
0
1
2
3
4
5
6
7
8
9
10
11
12
13
15
17
19
22
29
54
PROTECT
CLIP
SIGNAL
CHANNEL 2
0
1
2
3
4
5
6
7
8
9
10
11
12
13
15
17
19
22
29
54
PROTECT
CLIP
SIGNAL
CHANNEL 3
0
1
2
3
4
5
6
7
8
9
10
11
12
13
15
17
19
22
29
54
PROTECT
CLIP
SIGNAL
CHANNEL 4
0
1
2
3
4
5
6
7
8
9
10
11
12
13
15
17
19
22
29
54
PROTECT
CLIP
SIGNAL
7. Protect Indicators
These red LED indicate that the chan-
nel is in Protect mode. When the channel
goes into protect mode all output for that
channel will turn off by output relay. The
protect LED will light when overheating
or other severe problem occur. This is to
protect any speakers connected to the
channel. These LED light for approximate-
ly five seconds whenever the QA Series is
powered on and to fade slowly when the
amplifier is powered off. It is normal.
8. Channel input level control
These four 21-position detented con-
trols adjust input level for their respec-
tive amplifier channels. In Bridged Mono
Mode, only channel 1.3 input level control
are used to adjust signal level. In Parallel
Mode, all four input level control are used
to adjust signal level for their respective
amplifier channels. At their fully counter-
clockwise position, the signal is attenuat-
ed by more than 80dB. At their fully clock-
wise position, the signal is at unity gain.
When 0 dBu of signal arrives at the input
jacks and the Channel input level controls
are set to their fully clockwise position,
the QA Series delivers full power output.
Front Panel Controls
1
1
2
3
4
7
6
8
5
2
