Luxman SQ 202 amplifier & WL 212 tuner

General: 

This high quality amplifier produced in the early 1970’s. This amp is inside quite similar to the SQ 507x.

 

Specifications:

SQ-202 Specifications

Main Amp

Output:   70watts RMS 8 ohm both Channels driven   80watts RMS 8 Ohm Single Channel driven   100 Watts 4 Ohm Single Channel driven.

THD:  Below 0.04% 8 Ohm 1 k Hz  Below 0.05% 4 Ohm 1 Khz

Intermodulation Distortion:   below 0.05% 8 Ohm 70Hz:7k hz= 4:1

Power band width:    5~50khz (within -3db)    Frequency response: 10~60khz ( within -1db)

Input sensitivity: 700mv (8Ohm, 50watt) with level control

Input impedance: about 100k Ohms

Crosstalk:   66db

Residual noise :   About 1 mv

Damping Factor:   35 at 8 Ohms, 70 at 16 Ohms

Transistors:   2SD 218 (2) 2SA 649 (2) 2SC959 (6)  2SA 606 (2) 2SC 1000 (43) XA 495C (4)

Diodes:    Uo 5 (4) IS1850 (3) DS38B (4)

Pre-Amp

Rated output voltage Pre-Out : 700mV,   Tape out : 110mV

Maximum output Voltage:   aprox 5 V

Output Impedance:    Pre Out 100ohm; Tape out 100ohm

Frequency response:   20~70KHz within -1db THD below 0.05 Aux 1 kHz

Input sensitivity:   Pre out 700mv; Main 50Watt 8 Ohms,  Phono-1, Phono-2; 2mV. Aux 1,2,3 110mV. Mic mix 2.5 mV

Input Impedance:   Phono- 1 50K Ohms Phono -2 selectable 30K, 50K, 100k ohms. Aux 1,2,3. 100k ohms

Max input Voltage:   Phono-1, Phono-2 180 mV Aux-1,3. 5V Aux-2 adjustable level over 5 V

Hum and noise: (s/n ratio) pre out 700mV

Phono-1, Phono-2. 66db, Aux-1,2,3. 80db, Mic mix with Aux-1 66db  Weighted ( ihf “A” curve)

Phono-1, Phono-2 81db. Aux-1,2,3. 90 db. Mic mix with Aux-1. 75db

Noise voltage VS input:   Phono-1,Phono-2 -120db/V, Aux-1,2,3 -110 db/V, Mix(mix with Aux-1-118db/V   Residual Noise: 25uV

Crosstalk:  Phono 66db   Aux 71db.

Filters:   all 12 db/Octave, High Cut 5KHz, 9KHz.   Low Cut 30Hz, 80Hz

Loudness control:   50Hz +8.5db with attenuator on +7.5db     Attenuator: -18db

 

Photos:

 

Special futures:

 

Schematic:

      right-click on the pictures to download them and show them in better quality.  

 

Owners manual:

        construction.

 

Service manual:

click here to download the service manual of the Luxman SQ202

   

Modifications:

 

You can update the main power supply the common way: replace the 4 diodes for 8 into
2 bridges to separate power supply in two equal sections after the transformer, for each
channel one section and take 4 new capacitors of approx 6800 uF, 2 for each section,
ie. for each channel. Also check all caps in the power sections for the pre-amp.

You can replace all capacitors in the signal path and replace them for HQ polypropylene caps.

You can replace some resistors in the phono stage signal path, for metal film R's to get a quiet phono stage.
Also you can replace the transistors for more modern low noise transistors in the phono stage.

You can replace the final stage power transistors for better quality transistors with higher Ft.

You can replace the drivers of the power amp with BD139/140 and put little cooling heatsinks on them.

 

Sound:

These series of "High Quality" audio components soon got legendary of their outstanding quality and excelent sound performance.

Special thanks to Glenn Stewart from Australia and Helmut Geiselbrechtinger from Germany.

© Hans Hilberink - PE1MMK ® & Glenn Stewart & Helmut Geiselbrechtinger - Last update: 30-05-2013.