Lab.gruppen LAB 4000 - Manual (Page 3)

3
Introduction
Thank you for purchasing a LAB.GRUPPEN power amplifier. The amplifier you have chosen is the culmination
of many years of Research and Development. This amplifier makes amplification more controllable instead of
the traditional "Boring black box" you have become accustomed to.
Please take some time and read this manual to familiarize yourself with the advanced features of this amplifier.
The front panel
Figure 1. Front panel
1. Carry/protection handle
Both handles can be used to carry the amplifier, they
also act as protection for the front panel. If so desired
they can be removed (by removing the screws behind
the front panel) for fixed installations, or racks where
the front covers are to shallow.
2. Input level attenuators
These controls are used to alter the signal level
entering the amplifier. They are calibrated in dB to
help set up active loudspeaker systems or cut down
unwanted noise from the input signal.
(See page 9).
3. Over temperature protect indicator
This indicator is lit if the amplifier tries to operate
above its maximum operating temperature(90 o C).
The indicator first comes on as a warning to either
turn down the input level or check the cooling
arrangements after which point the amplifier will
mute the input signal. When the cooling fans have
returned the output heat sinks to the normal
operating temperature the input signal is unmuted.
4. VHF protect indicator
This indicator lights when constant signals, above
12 kHz at full power, are present at the output
terminals. When this happens the input signal is
muted and the process cycles until the VHF signal is
no longer present. (See page 9).
5. Clip/limit indicator
This indicator tells when the amplifier output is
clipping or limiting. The two different states can be
told apart:
• When the clip limiter is engaged it flickers
briefly. (See page 10).
• When the clip limiter is not engaged it lights for
a longer period.
6. Fan grill filter.
A foam filter is located behind the front panel to
prevent dust entering the amplifier.
7. Power actuator
This is used to start the amplifier.
(See page 5 and 8)
8. AC indicator
Indicate if AC voltage is present .
9. AFS indicator
Indicate if the adaptive fuse saver is activated.
4 0 0 0 CONVERTIBLE POWER AMPLIFIER
AFS
AC
VHF
TEMP
CLIP
- 5
-10
-15
-20
-25
ON
-80
-40
-20
-16
-12 -10 - 7
- 5
- 3
- 1
0 dB
CH. A
-80
-40
-20
-16
-12 -10 - 7
- 5
- 3
- 1
0 dB
CH. B
7 2 2
1
6 3 4 5 6 8 9