Luxman L-31

 The L-31 was designed to seek the best cost performance and to attain simplicity yet retaining the necessary features for true Hi-Fi from the view-point of practical use after an exhaustive review of current amplifiers in terms of both circuit and function.

Styling

Meticulous care is paied to the visual appearance and design to yield an image of high class audio component. An aluminium extruded front panelof light gold is housed in the massive wooden case in perfect harmony with metal and moulded knobs, whereas an attractive escutcheon is placed at the tone-control and lever switches. Needless to say the result of human engineering is taken into account and all the controls are arranged for the easiest operation.

 Circuit

The basic power amplifier section employs complete direct-coupled DC output amplifier circuitry with differential driving utilizing dual rail power supply to ensure a large damping factor down to the ultra low frequency range for driving the loudspeakers efficiently.

The output stage consists of by now mandatory pure complementary circuit with combination of PNp and NPN transistors. Thus crossover distortion is kept extremely low, while high reliability is realized by means of TO-3 transistors with good heat-dissipation. At the same time the transistors of high cut-off frequency at the driver stages suppress distortion in the treble range. The biggest problem in the pre-amplifier section lies in noise, which was solved by using ultra low noise transistors and resistors in addition to low leakage electolytic capacitors.

The equalizer stage is composed by 2-step direct coupled amplifier of PNp and NPN transistors, which ensures excellent linearity and sufficient phono overload voltage of 150 mV 91 kHz, RMS, phono).

Independent tone-control of the well-known Lux exclusive NF type is provided for both right and left channels, whose mechanical centre point offers a true flat frequency response.

The overall harmonic distortion at the pre- and main-amplifier is no more than 0,05% and I.M. distortion is also no more than ,01%. While the S/N ratioat phone exceeds 64 dB.

The annexed accessories imperative for daily use are provided such as tape monitor circuit, DIN tape connector, speaker selector, etc.

Specifications

Power Output RMS:  38 W/38 w (8 Ω, both channel driven)

Total Harmonic Distortion:  no more than 0,05%

I.M. Distortion:  no more than ,01%

Power Bandwidth:  10 -50,000 Hz (-3 dB less than 0,1%)

Frequency Response:  15 - 50,000 Hz (-1 dB)

Input Sensitivity:

Phono :  2,6 mV

Tuner, Aux 1, 2 :  150 mV

Input Impedance:

Phono ;  50 k Ω

Tuner, Aux 1, 2 :  more than 60 k Ω

Signal-to-Noise Ratio:

Phono :  more than 64 dB

Tuner, Aux1, 2 :  more than 83 dB

Monitor :  more than 83 dB

Residual Noise:  -87 dB

Tone Control:  lux type NF tone Control

High Cut :  7 kHz - 6 dB/oct

Low Cut :  70 Hz - 6 dB/oct

Damping Factor:  more than 90 dB (8 Ω)

Semiconductors:  27 transistors; 8 Diodes; 2 Zener Diodes; 1 LED

Power Supply:  110-120, 220-140 V 50/60 Hz

Power Consumption:  170 W (8 Ω, max output, both channel driven);  150 W (CSA, UL rated)

Dimensions (W x H x D):  440 x 160 x 225 mm (17-3/8" x 6-5/16" x 8-7/8")

Weight:  7 kg (15,4 lbs) net