L-ACOUSTICS LA 24 MANUAL Version 2.2
17/11/08 18
•
DESIGN FEATURES
Cooling
L-ACOUSTICS amplifiers
run very cool due to a patented heat sink device called the
Intercooler
TM
. First, bipolar output devices are mounted directly on a copper heat sink
thereby avoiding thermal losses normally found when using mica washers. The heat sink is
then mounted horizontally in front of a pressure chamber where the air flow is constant along
the entire length of the heat sink due to a horizontal pressure chamber that is created in front
of it (by comparison, for a conventional tunnel design the end of the heat sink opposite the fan
invariably gets hotter than that directly in front of the fan). When cool air in the pressure
chamber hits the geometric fins of the
Intercooler
TM
, turbulence is produced thereby
enabling efficient cooling.
Light weight
The LA 24 has an excellent power to weight ratio, (280 W/Kg) making it one of the most
powerful 2U amplifiers available. The light weight is achieved not only through use of the
switch mode power supply - the
Intercooler
TM
and 9 piece anodized alloy chassis also
contribute greatly, making rear rack supports unnecessary in many applications.
Switch mode power supply (SMPS)
Switch mode power supplies are the modern solution to the problems of size and weight.
However, early examples of SMPS used for power amplification in audio applications were
less than impressive and literally adopted the type of supply found in many computers today.
The L-ACOUSTICS SMPS is different in that it is regulated. How is this achieved?
In contrast to other designs that use push pull converters we have managed to produce a
SMPS that has the same characteristics as a conventional power supply. We have avoided the
pitfalls of push-pull converters by eliminating the need for limiting on the secondary side of the
switch transformer. This is achieved by using sense windings and injecting a magnetic pulse
from the AC line during a pulse time segment which is separate from the output charge
current pulse.
2
1
3
0
10
20
30
40
50
60
70
80
90
0
5
10
15
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Current [A]
V
o
lt
a
g
e
[
V
]
Figure 14. Current-voltage characteristic of different power supply topologies
.
1) Conventional power supply shows voltage drop due to internal resistance
2) Regulated power supply used by L-ACOUSTICS
3) Unregulated switch mode power supply with current limiting
