Luxman SQ700X

The new integrated amplifier ranked in between the best-seller SQ707 and the renowed SQ500 series amplifiers. The most up-to-date circuitry of direct coupling and differential driving under pure complementary configuration ensures the excellent power response combined with extremely low distortion in main- and pre-amplifier stages alike. No comparable component amplifier in this price bracket available today in respect of its power and performance capacities, its attention to human factor in handling and its attrac tiveness.

Circuit/Performance

Preamplifier section is composed by 2-stage direct coupling circuit at equalizer stage with PNP and NPN transistors, which improves linearity and utilization of mains power. The withstand input voltage at Phono terminals is set at 200mV (1kHz which surpasses that of pre-main amplifiers in this class. Stability is enhanced by feedback given from the 2nd stage collector to the 1st stage emitter.

For better S/N ratio low-noise transistors are adopted and mylar and tantalum types of lower leak current are used as an interstage coupling condenser. PNP transistors which inherently excel in noise figure are specially selected for the equalizer stage, and above all the rapresentative one 2SA493 is mainly utilized throughout whole section of pre-amplifier.

Main amplifier section is composed by full stage direct coupling circuit with dual power supply system and 1-stage differential amplification circuit, which ensures the excellent power charactor and dampling factor throughout whole frequency range from ultra low end to extremely high end. Pure complementary configuration with PNP and NPN power transistors at output stage throughly eliminates the cross-over distortion and ensurest the most faithful reproduction to the original sounds.

Continuous output is 20W/20W(8Ω) with both channels simultaneously driven, and at this rated output both THD and intermodulation distortion are kept below 0,1%. Power bandwidth is sufficiently wide with 10-50,000Hz with constant damping factor of 38(8Ω) throughout whole audible range. The residual noise is kept below 1mV.

Function

An attenuator reduces the gain by 1/8, and is used as a temporaily sound subduing switch. Tone controls are of Lux NF type independently arranged for right and left channels with click-stoppers for easy recognition of attenuation intensification degree. Furthermore for subtle tone coromation 2-point turn-over (roll-off) frequency selector is provided both for bass and treble. Also the defet switch is provided to restore the flat frequency response under the fixed tone control. 2 pairs of speaker terminals are available, either of which can be selected by the speaker switch. Moreover this amplifier is equipped with tape-monitor circuit, DIN connector, and head-phone jack.

Mechanical/Styling

The front control panel is of extruded aluminium with white-gold hair-line finish to give an elegant refined appearance. The knobs are of the same finish. This amplifier is housed in the case of dignified rose wood finish. Conjointly with amelioration in performance meticulus care is paid to the human factors in handling accessibility, soft felling, etc.

Specification

Main Amplifier

Power Output (IHF):

70 W per channel at 4 Ω

40 W per channel at 8 Ω

Total Harmonic Distortion: less than 0,1% (8Ω, 20W)

Intermodulation Distortion: less than 0,1% (8Ω, 20W)

Power Bandwidth: 10 - 50,000 Hz (-3dB, 0.1%)

INput Sensitivity: 430 mV (8Ω, 20W)

Input Impedance: 40 kΩ

Residual Noise: less than 0,5 mV

Damping Factor: 38 at 8Ω; 76 at 16Ω

Pre-Amplifier

Output Voltage: Pre-Out: 430 mV

Output Impedance: Pre-Out: about 100Ω

Frequency Response: 10 - 50,000 Hz (-1 dB)

Total Harmonic Distortion: less than 0,04% (1 kHz, 1V)

Input Sensitivity

Phono1, Phono2: 2 mV

Aux1, Aux2: 120 mV

Input Impedance:

Phono1, Phono2: 50 kΩ

Aux1, Aux2: 50 kΩ

S/N Ratio:

Phono1, Phono2: more than 60 dB

Aux1, Aux2: more than 70 dB

Max. Permissible Input Voltage: phono; 200 mV (1 kHz)

Residual Noise: less than 45 μV

Tone Controls (Lux NF type with turn-over):

Bass Control: 250 Hz, 500 Hz

Treble Control: 2,5 kHz, 5 kHz

Components

Transistors: 2SD155(2), 2SA616(2), 2SC495(5), 2SA505(2), XA495C(5), 2SA493(8), 2SC1000(4)

Diodes: 5B1(1), SR1K-4(1)

Varistors: KB265(4)

Annexed Controls: attenuator, speaker switch, tone defeat switch, headphonejack, etc

Power Consumption: 100 W

Dimensions (W x H x D): 373 x 125 x 227 mm

Weight: 7,8 kg