Kenwood L-A1 Instruction Manual page 6

About your new Kenwood L-A1 amplifier
Tan) e)cenacxe me hvaal-lanlrom-}(erar-]mcomare)(si-m ec] ale) All the power you need and more
® Super C!
All amplifier circuits in the Kenwood L-A1 amplifier
use our newly developed Super C' circuits (Super
Constant Current Cascade Circuit). While most
amplifiers use differential amplifier circuits, in
designing the Super C4 we focused on a new way
of reducing the in-phase noise normally suppressed
by using the common-mode rejection ratio (CMRR)
inherent to differential amplifiers. The result was a
dramatic reduction in the noise generated in the
first stages of the amplifier circuits.
+VCC
Ordinary design
OUT
OUT 2
N41
IN2 0
— ts VES
L-A1
4VCC
CC
e Revolving resistor volume
The master volume of the L-Al amplifier uses a
newly developed large-scale (type 32) revolving
resistor volume. While ordinary volumes have a
slider that moves over the resistor, the slider in the
L-A1 is fixed over the volume while the resistor is
rotated. This design eliminates the connection
formerly created by crimping between the printed
circuit board and the resistor and allows the
amplifier to deliver better sound. This revolving
resistor design also makes it possible to realize
special variant control characteristics which in turn
made it possible for us to use a master volume with
the unbelievably low impedance of 1k Q. This gives
you the low impedance you need in actual use, and
reduces the noise generated from the volume and
main amplifier to the barest minimum.
® Multiple-driver system
The power amplification system uses four parallel push-pull circuits with large-scale transistors (Pc=120W),
which make it possible for the L-A1 to produce strong output even when the impedance of speaker systems
has fallen low at some frequencies. In ordinary parallel push-pull circuits, only the power transistors in the
final stage are connected in parallel, while all other driver transistors in the previous stage are usedin common. .
The multi-driver system used in the L-A1, however, includes a group of driver transistors for each group of
power transistors in a design that connects four groups of Darlington circuits in true parallel. This circuit
structure reduces the load on individual transistors, making it possible to gain a stable circuit operation with
sufficient current and less heat.
Ordinary design L-A1
IN t+-———o OUT iNO———~+ —O OUT