LUXMAN L-503s

Commentary

This is a pre-main amplifier with improved cost performance while applying Luxman's technology.

CSSC (Complementary Single Stagger Circuit) circuit is adopted for the amplifier section.
This circuit is roughly divided into three parts. From the input side, the complimentary service amplifier, the second stage current transmission stage, and the last stage output circuit. The differential amplifier gains the inherent gain of the amplifier circuit. The current transmission stage uses a common-base transistor circuit that is used in high-frequency circuits that require high fT (cutoff frequency) transmission. The output circuit amplifies power.
Many general amplifiers have amplification functions in the first and second stages. Since the cut-off frequencies of the first and second stages are approximate values, there is a large phase shift in the ultra-high frequency range as a total characteristic. Therefore, analog information from the output is inverted and returned to the input using NFB. This structure improves electrical characteristics. However, when a large phase shift occurs, the feedback becomes close to positive, and positive feedback oscillation or similar unstable state occurs. In order to avoid this, another local feedback loop is used as a complementary loop. However, this high-frequency correction loop itself greatly affects sound quality and causes a loss of natural feeling of sound.
In the CSSC circuit, the cut-off frequency in the high-frequency range is extremely high in the second stage common-base type current transmission stage. Therefore, it can be said that the frequency characteristics of the first stage differential amplifier control almost the entire CSSC. Stable operation can be ensured with minimal correction, and high-through rate is achieved.

It is equipped with LUX's unique OD β circuit.
The OD β circuit is the β circuit (NFB) of the amplifier, to which LUX added its own ingenuity. In a general amplifier, the NFB is fed separately in the direct current and AC regions. However, by inserting a DC servo amplifier into the feedback loop in order to ensure stability in the DC region, a difference in balance with the AC region was caused. In the OD β circuit, excellent DC stability is ensured only by basic DC feedback without incorporating a DC servo amplifier by refining the bare characteristics of the circuit to a high degree. In addition, the NFB in the AC region has been optimized to adjust the energy balance in all bands and achieve a sense of uniformity in tone quality in all frequency bands.

The power amplifier has a 3-stage Darlington configuration and uses a complimentary service circuit with low internal impedance, high current, and high fT type power transistors (Pc150W, Ic (max) 15A).
In addition, stability is enhanced by using parts such as a large heat sink, high-voltage driver transistors with excellent hfe linearity, and dual transistors for differential amplification.

The power supply section is equipped with a large high-efficiency EI core power transformer and a large capacity electrolytic capacitor.

It comes with a wireless remote control for power on / off, input selection, volume control, muting on / off, etc.
A motor drive volume is used for the volume control, and the input switch is also a motor drive type. This input switch gives a clear click feeling to the step for each position when operating on the amplifier panel. When operating the remote control, the clutch mechanism allows the remote control to rotate smoothly without clicking.

The internal layout uses a partition structure to reduce interference noise and distortion by separating circuits such as the preamplifier, power amplifier, input / output terminal, power supply input, and speaker output.

The interior uses LUX's own custom parts to improve the sound quality.
The speaker terminal is a large terminal that can be attached to a banana plug.

The speaker output is equipped with a large, highly reliable speaker relay and an independent headphone relay.
We have also achieved low impedance by introducing bus bars.

It has phono inputs for MM, four line inputs and one balance input.
Two input / output terminals for recording are provided.

It includes tone control, loudness and subsonic filter, balance control, recording selector, and mode selector.
It is also equipped with a line straighter function, which can provide high quality sound by bypassing unused circuits (tone control, mode selector, left / right balance).

An inverted switch is mounted, and the phase of the balance line input can be inverted.

Equipped with line phase sensor, polarity can be checked when power plug is inserted.

Custom type power cable and AC inlet are adopted.

It is equipped with a bus line that links remote control operations of LUXMAN CD players.

Model Rating

Type	Integrated amplifier
Continuous effective output	65W + 65W (8 Ω)
Total harmonic distortion factor	0.003% or Less (8 Ω, 1 kHz, Rated Output, Line Straight on) 0.02% or Less (8 Ω, 20 Hz to 20 kHz, Rated Output, Line Straight on)
Input Sensitivity / Impedance	Phono : 2.5mV/47k Ω Line : 150mV/47k Ω Tape : 150mV/47k Ω Bal. Line : 300mV/66k Ω
Output voltage	Tape:150mV
S/N ratio (IHF-A correction, Line Straight on)	Phono : 90 dB or more (5 mV input) Line : 107 dB or more (input short circuit)
Frequency response (Line Straight on)	Phono : 20 Hz to 20 kHz + 0 -0.5 dB Line : 20 Hz to 100 kHz -2dB or less
Tone control	100 Hz : + / - 10 dB max (+ / - 1.5 dB) 10 kHz : ± 10 dB max. (± 1.5 dB)
Loudness control	100 Hz : + 7 dB (+ / - 1 dB) 10 kHz : + 5 dB (+ / - 1 dB)
Attachment	Recording selector Speaker selector (A/B) Mode selector Tone control Balance Straight Line Subsonic Loudness Phase inverter Line phase sensor Remote control Headphone jack
AC outlet	Unswitched : 2 lines, Total300Wmax
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	150W (Electrical Appliance and Material Control Law)
External dimensions	Width 467x Height 179x Depth 440 mm
Weight	14.0kg
Attachment	Wireless Remote Control