LUXMAN L-48A

Commentary

Stereo pre-main amplifier with duo-beta circuit.

LUX's unique duo-beta circuit is used for the equalizer amplifier and power amplifier.
The duo-beta circuit consists of an appropriate amount of NFB and DC servo. First of all, the TIM distortion is reduced by applying an appropriate amount of NFB based on an amplifier circuit with excellent bare characteristics. This contributes to the reproduction of sound quality and atmosphere in the middle and high frequency range. The DC servo solves the problem of intermodulation distortion and DC drift due to harmful ultra-low frequency components, and at the same time achieves excellent speaker braking effect.

The duo-beta circuit realizes high gain of the equalizer, and not only MM cartridge but also MC cartridge can be directly connected to the equalizer.
The circuit is composed of a cascode differential input first stage circuit with bootstrap by low-noise FET and an output stage adopting A-class single-ended push-pull circuit, making it an excellent configuration with bare characteristics.
In addition, because the gain of the equalizer itself is high, we have succeeded in eliminating flat amplifiers that cause poor sound quality.
(The input sensitivity of the MC input terminal is 0.3 mV and most MC cartridges can be connected. However, it is recommended to use high-impedance type cartridges as much as possible.)

For the output stage, a large power transistor with high ft (high cutoff frequency) and low Cob (collector output capacitance) is carefully selected and used. The driver circuit is also high-speed to eliminate switching distortion.
In addition, a newly developed loop heat pipe has been adopted to increase the heat radiation effect.

A line-and-straight configuration is adopted, and the configuration in which the MC equalizer and the power amplifier are directly connected enables faithful transmission.

LUX type NF tone control is used for the tone control.
The turnover frequency can be switched to two levels in each high and low range, and complete bypass is also possible by setting it to the defeat position.

Equipped with 10-element left and right independent indicators that display peak power in real time.
It uses a watt display that can read the output directly, and it can be turned off with a switch when it is not necessary.

Equipped with 2 types of tape monitor, dubbing switch, subsonic filter and high-cut filter.

Model Rating

Type	Integrated amplifier
Continuous effective output	70W + 70W (8 Ω, both channel operation, 20 Hz to 20 kHz)
Total harmonic distortion factor	0.03% (8 ω, 70W, 20 hz to 20 khz)
Cross modulation distortion factor	0.03% (8 ω, 70W, 60 hz : 7 khz = 4 : 1)
Frequency characteristic	Phono MM, MC : 20 Hz to 20 kHz ± 0.3 dB Tuner, AUX : 10 hz to 100 khz -1dB
Input Sensitivity / Impedance	Phono MM : 1.2mV/50k Ω Phono MC : 0.3mV/100 Ω Tuner, AUX : 190mV/50k Ω
Signal-to-noise ratio (IHF-A)	Phono MM:77dB Phono MC:71dB Tuner, AUX : 105 dB
Subsonic filter	15 Hz, 30 Hz
High-cut filter	9 kHz, 15 kHz
AC outlet	Switched : two systems Unswitched-One system
Power consumption	250W
External dimensions	Width 466x Height 145x Depth 333 mm
Weight	12kg