LUXMAN SQ503X

Commentary

As the economic type of the SQ505X, this pre-main amplifier is designed with emphasis on practicability and without waste.

The main amplifier section uses ± 2 power supply system and all stages are directly connected without the output capacitor, so that the power character and damping factor up to the ultra-low frequency range are sufficiently secured.
Pure complimentary service system composed of PNP type power transistor and NPN type power transistor, and crossover distortion is also removed.
The first stage consists of a constant-current differential amplifier with a low-noise PNP transistor to maintain high stability against DC drift.

The equalizer stage of the preamplifier section consists of a 2-stage direct connection circuit. The PNP and NPN transistors are used to improve the linearity by improving the power supply utilization factor. The stability is also improved by applying DC feedback from the second stage collector to the first stage emitter.
The pre-section uses ultra-low-noise silicon transistors in all stages, and is composed of carefully selected PNP transistors with superior noise figure in nature, which further reduces the harsh mid-to-high-level noise characteristic of transistors.
In addition, tantalum type and Mylar type capacitors with low leakage current are used as coupling capacitors between stages to eliminate unpleasant shock noise when switching switches.

LUX type NF type is used for tone control.
The left and right channels are independent, and the bending point can be switched by two points each for both low and high frequencies.

With an attenuator, the gain can be reduced by 18 dB without using volume.

Equipped with two types of speaker terminals.

Equipped with a tape monitor and DIN connector.

The front panel is made of aluminum material with hairline processing. It is white gold anodized.

Model Rating

Type	Solid-state integrated amplifier
Main Amplifier Section
Continuous output	20W + 20W (8 Ω, both channel operation) 25W/25W (8 Ω, single-channel operation)
Total harmonic distortion factor	0.1% or Less (8 Ω, 20W)
Cross modulation distortion factor	0.1% or Less (8 Ω, 20W, 70 : 7 khz = 4 : 1)
Output bandwidth	10 Hz to 50 kHz -3dB (0.1%)
Frequency characteristic	10 Hz to 80 kHz (-1dB or less)
Input sensitivity	430 mv (8 Ω, 20W)
Input impedance	45k Ω
Damping factor	38 (8 Ω) 76 (16 Ω)
Residual noise	1 mV or less
Preamplifier Section
Frequency characteristic	10 Hz to 50 kHz -3dB (Aux1)
Total harmonic distortion factor	0.04% or Less (1 kHz, 1 V, Aux1)
Input sensitivity	Phono1, 2 : 2 mV Aux1, 2, 3 : 95 mV
Input impedance	Phono1, 2 : 50k Ω Aux1, 2, 3 : 50k Ω
Signal-to-noise ratio	Phono1, 2 : 60 dB or more Aux1, 2, 3 : 70 dB or more
Maximum Allowable Input (1 kHz)	Phono:210mV
Tone control	LUX System NF Type with Bending Point Switching Low-range bending point : 200 Hz, 400 Hz High-frequency curve point : 2.5 kHz, 5 kHz
Residual noise	45 μ V or less
Crosstalk (1 kHz)	Phono : -60dB or less Aux : -65dB or less
<General>
Attachment	Attenuator (-18dB) Speaker switch (2 systems) Premain isolation switch Tape monitor circuit DIN connector
Semiconductor used	Transistor : 27 Diode : 2 pcs Varistor : 4 pcs
Power consumption	100W (8 Ω simultaneous load at maximum output)
External dimensions	Width 450x Height 160x Depth 268 mm
Weight	10kg