Lab.gruppen LAB 4000 - Manual (Page 7)

7
9. Connecting speakers
Speaker connections are made via the two Neutrik
NL4FC Speakon connectors (1).
They are the only connectors currently available to
meet the EC safety requirements. They are wired in
the following manner:
Pin -1 Speaker ground.
Pin +1 Speaker positive.
Pin -2 No connection.
Pin +2 No connection.
Figure 9. Speakon connector
Please note that this is the standard wiring
convention for Speakon connectors adopted world-
wide.
Never connect either output terminal to ground
or to some other output or input terminal (see
warning on page 2).
For normal two-channel operation, connect each
speaker load across the outputs positive and ground
terminals. Pay attention to speaker polarity;
loudspeakers connected out of polarity degrade
sound quality and may be damaged as a
consequence.
Keep the speaker cable wires as short as possible,
and use a good quality stranded speaker cable. Do
not use shielded wire, such as microphone or guitar
cable. Remember that the speaker cable robs the
power of the amplifiers in two ways:
Increases the load impedance and introduces
resistive power losses, so called I 2 R losses.
10. Load matching (MLS-switches)
The MLS switches is located on the rear panel. The
MLS switches offer a impedance matching, so you
can drive the LAB 4000 in 2 ohms without
increased heat losses.
As stated earlier the LAB 4000 can produce 2100
watts into both 4 and 8 ohms. This is done with the
aid of the MLS TM switches( 2 ).
The fixed positions shown in Table 2. guarantee
2100 watts but higher powers can be achieved
utilising higher MLS TM positions when connected
to lower impedance's see Table 2.
As you can see from Table 2 the LAB 4000 can
produce in excess of 2100 watts
Table 2.
Figure 10. MLS switches on rear panel
MLS TM positions can be different for each channel
and a variety of combinations can be achieved see
Table 3.
Channel Impedance MLS Power Comments
A 8 -2dB 820W Power
B 8 -2dB 820W reduction
A 4 0dB 2100W High peak
B 4 0dB 2100W power
A 8 0dB 1300W Power
B 2 -5dB 1660W matching
A 8 -2dB 820W Power
B 4 0dB 2100W sharing
The way to find the best MLS TM position for your
application is by experimentation, the amplifier is
very well protected (even down to 0.3 ohms), but
where speed is of essence stick to the fixed
positions.
The thing to remember with the LAB 4000 that it is
a power converter and when you select MLS TM
positions you are allocating a portion of power from
5000 watts.
LAB 4000
LOAD CONFIGURATION -5 dB -4 dB -2 dB 0 dB
16 ohms Stereo (2 channel) 220 w 260 W 410 W 650 W
8 ohms Stereo (2 channel) 430 W 520 W 820 W 1300 W
4 ohms Stereo (2 channel) 830 W 1000 W 1600 W 2100 W
2 ohms Stereo (2 channel) 1660 W 2000 W 2200 W 2400 W [1]
3050 W [2] 3200 W [2]
16 ohms Bridged mono 860 W 1040 W 1640 W 2600 W
8 ohms Bridged mono 1660 W 2000 W 3200 W 4200 W
4 ohms Bridged mono 3320 W 4000 W 4400 W 4800 W [1]
[1] Component tolerance dependent
[2] Continuous power, one channel driven or peak power both channels driven.
(Thermal protection may occur at high continuous power).
Power in watts (EIA 1 kHz, 1% THD)
MLS SWITCH SETTING
OUTPUT CH.B
ML
S
Sw
it
c
h
0
- 2
- 4
- 5
dB
1+ CH.B+
1- CH.B-