DC Monaural Power
Amplifier
An extre,ely compact
monaural power amp of unique appearance design for those who pursuit perfect
performance!
A lot of merits are
obtained by making a monaural power amplifier. For instance, addition of a
monaural power amplifier for use in driving a bass range unit easily realizes a
3D-system. Also positioning is flexible, therefore placing the amplifier near the
speaker system is feasible. But above all, in pursuit of perfect performance,
one has to inevitably divide function into many ways. In this respect, monaural
power amplifier is the most suitable. But we dare say it is not sufficient
merely to make a power amplifier monaural. It is necessary to scrutinize every
possible aspect such as sonic quality, appearance design, chassis construction,
and functions etc. to realize the ideal power amplifier.
The B-12 is an
extremely compact monaural power ampl of unique appearance design. The rated
output is 150 W minimum continuous into 8-ohm loads, from 20 Hz to 20 kHz with
no more than 0,006% THD. In the output stage, power transistors are arranged in
triple push-pull to use the most linear portion of each transistor effectively,
and produces large output quite smoothly. Of course the Transient
Intermodulation distortion is completely eliminated thanks to LUX's original
"Realtime Processed" DC-amp. Almost perfect counter-measures are
taken to reduce the Notch distortion which cannot be removed even if the
amplifier is a DC-amp. Specially selected high speed transistors are arranged
at the driver stage and the power output stage. Further class "AB"
operation is adopted at the output stage. This has been made possible thanks to
a large and effective heat-sink (which represents an important portion of the
appearance design) and a huge toroidal power transformer.
It is difficult to
design DC-amp circuitry for a large output power amplifier, since the DC-drift
caused by the change of ambient conditions such as temperature becomes more
severe as the power increases. To suppress this DC-drift, LUX's original DML-IC
which includes the first stage differential amplifying circuit, the cascode
circuit to assist it, and the constant current circuit is used. Further, the
transistors arranged at the second stage differential amplifying circuit and
the constant current circuit are thermally coupled. Of course those components such as resistors
or capacitors of good temperature characteristic are carefully selected. All
these contribute to suppress DC-drift completely. Thus, in the B-12, stability
and large power output have been combined in an ideal power amplifier.
The power supply
section of a power amplifier directly affects its characteristics. Therefore,
two low-impedance, large-sized electrolytic capacitors (15,000µF) are coupled
to the huge and highly efficient toroidal power transformer, which enables the
amplifier to produce high power output of 150 W quite smoothly. The power
supply to the pre-driver stage is, of course, regulated.
Specifications
Power Output: 150 W minimum continuous
Rated
I. M.: no more than 0,006% (8Ω, 150W, 60Hz : 7 kHz = 4 : 1)
Frequency
Response: DC -100,000 Hz (within -1dB)
Input
Sensitivity/Impedance: 900 mV/20 kΩ
Signal-to-Noise
ratio: better than 110 dB (IHF-A
weighted, input short-circuited)
Damping
Factor: 120 (8Ω,1 kHz)
Protection
Circuit: Speaker protection by sensing
DC-drift, Overcurrent Protection Circuit
Additional
Features: Input Capacitor IN/OUT
Selector; Input Attenuator
Power
Consumption: 320 W (8Ω, at full power)
Dimensions (W x H x
D): 436 x 95 x 328 mm (17-3/16" x
3-3/4" x 12-15/16")
Weight: 11,5 kg (25,3) net
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