5
LAB.GRUPPEN switch mode amplifier use
primary switching, i.e. the mains is rectified
directly before the transformer, which means that
the power supply is insensitive to the mains
frequency and will operate from DC to 400 Hz.
The amplifier is supplied with an approved European
AC line connector. If this connector is not
appropriate for your country, it can be cut off and
wired to a suitable connector in the following way :
BROWN
LIVE
BLUE
NEUTRAL
GREEN/YELLOW
EARTH
Once the AC connector is connected to a suitable AC
supply, the amplifier can be started with the AC
actuator. When you power up the amplifier it takes a
couple of seconds to check its circuits (this is known
as the "soft start" or "slow start" sequence), the fans
then blow at high speed before going onto "idle" and
the 2 bottom green LED’s come on to show the
output circuits are receiving the correct rail voltage.
4.
Denmark: National deviation
concerning installation of the LAB 4000:
Danish safety regulation only permits 8A main
fuse. As the LAB 4000 use an internal primary
mains fuse of 15A, the LAB 4000 must be
equipped with an industrial mains connector rated
for 16A, or as an alternative be fixed installed to a
16A circuit.
5.
Switzerland: National deviation
concerning installation of the LAB 4000:
Swiss safety regulation stipulates that mains
connector of the type 23 must be used.
6. Grounding
There is no ground lift switch or terminal on this
amplifier. The signal ground is always floating via a
resistor to chassis and the grounding system is
automatic. If a potential above 0.6V presents itself
between signal ground and chassis ground, a short
circuit is introduced between the two, thereby
enabling electrical protection. If a unit in the system
is faulty, its mains fuse will blow, due to this
automatic ground system.
If however you wish to tie the signal ground to
chassis,
connect the XLR-connector’s shell lug to pin 1. In
the interest of safety never disconnect the earth pin
on the AC cord.
For all units that are EMC approved (radio
interference), there is an AC mains filter. This filter
needs the chassis ground for reference, otherwise a
current loop is formed via the signal ground.
Use the balanced input to avoid hum and
interference.
7. Power consumption
There are three ways to determine the power/current
consumption of the amplifier:
First, the peak current draw at full output
power. Under this condition the power will trip the
wall breaker within 30 second and the amplifier
will operate for less than 2 minutes before
thermally limiting. During this time, the
temperature of the power supply will be stabilised
at a temperature that will have no effect on the
insulation rating of the AC line cord.
Secondly, the maximum expected average
current under worst case program material which is
1/3 of full power according to the FTC-standard. At
this level the music will be in the state of constant
clip and is therefore the highest power level one can
obtain without completely obliterating the program.
At last, the "normal operating power", as
measured according to the safety standard IEC 65
and used by a majority of safety agencies. The
normal operating power is measured using pink
noise, with an average output power equal to 1/8 of
full power. The one eighth of the total power is as
loud as you can play music while making some
attempt to avoid obvious clipping. It also
corresponds to a headroom of 9dB, which is very
low for an audio program.
In 2 ohms operation, the AFS-protection of the
amplifier circuit will not permit long term current
draw and the component temperature rise will
stabilises well below the rating.
Table 1.
The current draw
can be calculated by dividing the mains input power by the mains voltage.
We recommend you to design the power distribution for at least the current at 1/8 power and 1/3 power for
heavy duty demands like discos etc.
The heat power
can be calculated as the following example:
We consider a headroom of at least 9dB and a 4 ohms load on an amplifier producing 2100 watts per channel.
The 1/8 power per channel is then; 2100 / 8 = 263 watts, total output; 2 x 263 = 525 watts.
MAX OUTPUT POWER
MAINS INPUT POWER
Power
Full Power 1/3 Power 1/8 Power Idle
sine wave
note 1
note 2
LAB 4000
8 ohms
2X
1300
3500
1400
800
130
4 ohms
2X
2100
6000
2300
1300
130
2 ohms
2X
2400
6900*
2900
1500
130
* Will be reduced by AFS protection
note 1
Average power with music as program source
Normal" music power with 9dB hea
The amplifier driven to clip levelnote 2 IEC standard power rating.