Realtime Processed DC Power Amplifier (1978-81)
The Luxman 5M21 is a stereo power amplifier which constitutes part of the Laboratory Reference Series. The output is 100W per channel into 8 ohms.
Function wise this is provided with 2 large VU meters to monitor an output power on both right and left channels, meter sensitivity, and DC offset censer to check DC components at the input.
As explained by the words Realtime Processed, with the 5M21 we delved not only into spatial wave form but also into time problem (phase) so as to ensure the most faithful amplification of the music signals - passing and unrepeatable wave-form signals.
Especially to remove the phase distortion at the bass range a DC configuration was adopted, and also as regards the harmful notch distortion at the treble range, exhaustive study rendered on the components as well as the circuitry made it possible to reduce it lower than even that of class A amp without sacrifice of output power.
The advantage of DC amp has been fully appreciated, but such configuration has never been taken up by the major manufacturers because of its inherent drawback of DC drift triggered by fluctuation of temperature and other ambient conditions. However this barrier is successfully removed, and a DC amp of unconditional stability is realized thanks to the newly developed FET's differential circuit and its auxiliary circuit of DML-IC.
In addition, to ensure stable power supply to all the circuits involved, we combined 2 independent large toroidal power transformers for right and left channels with electrolytic capacitors of huge capacitance and low impedance. Such components as resistors, semi-variable resistors and capacitors are carefully selected.
Power output: 100 watts per channel into 8Ω (stereo)
Frequency response: 1Hz to 100kHz
Total harmonic distortion: 0.008%
Damping factor: 80
Input sensitivity: 0.89V
Signal to noise ratio: 120dB
Semiconductors: 2 x IC, 49 x transistors, 43 x diodes
Dimensions: 442 x 400 x 146mm
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Reviewed Sep 29th, 2016 by coolsc21
For this amplifier, there is only to say. The unit is made in the time when honor and respect were the words. If you take a look inside the amplifier, you will see the engineering arts and crafts of high quality.