5687 based simple preamp Basic layout DIY Paradise

5687 based simple preamp Basic layout DIY Paradise 9 January 2003

6 X 4 Schematic Signal circuitry courtesy of vt 4 c@hotmail. com 5687

Output RCA jack IEC socket Input RCA jack Power transformer 6 X 4 50+50 u. F/ 500 V electrolytic capacitor Stereo volume pot 5687 Chassis Layout Top View

Input RCA jack IEC socket Output RCA jack 30 H chokes 50+50 u. F/ 500 V electrolytic capacitor Few points to note here. Power circuitry is kept at center. Signal comes in from the input RCA jack, goes to volume pot, then tube, then routes to output RCA jack. Coloured wavy line shows signal path. 6 X 4 The purpose of doing the layout is to avoid stray flux (from transformer, chokes) from coupling into your signal and also to ensure components are not too cramped together to the extent that there isn't enough ventilation. Stereo volume pot 5687 Chassis Layout Bottom View

The following wiring diagrams are meant to aid you in the sequence in wiring this preamp. Of course, you can do it some other way. Any other way, actually. Please note that layout of components is not to scale, so when you plan your chassis, don’t simply “follow” what you see here. Remember basic rules still apply: • keep signal wires far away from filament wires transformer, chokes and tube rectifier. • cross only at 90 degrees. • twist tightly the heater wires, place close to chassis. • maintain star ground. SAFETY FIRST: REMEMBER TO SOLDER IN BLEEDER RESISTOR! REMEMBER TO “EARTH THE CHASSIS”! You “earth the chassis” by wiring Earth of IEC socket to chassis, through a nut. THEN confirm the resistance between Earth of IEC and chassis is as close to zero as possible.

Input RCA jack short to chassis Output RCA jack insulated from chassis 6 X 4 1 2 3 4 7 50+50 u. F 500 V 6 5 Using tube socket spigot as ground 9 Gnd Out In Unused Alps stereo pot 1 8 2 7 5687 3 6 5 4 Ground layout

3. 15 -0 -3. 15 V 1 2 3 4 7 6 9 Gnd Out In Unused Alps stereo pot 3. 15 -0 -3. 15 V 5 1 8 2 7 3 6 5 4 Wiring of heaters

30 H choke 350 -0 -350 V 1 2 3 4 7 6 5 Bleeder resistor. Very important!!!!! 270 kohm 2 W Tap B+ from here 9 Gnd Out In Unused Alps stereo pot 1 8 2 7 3 6 5 4 Wiring of power supply

L / R Input L / R Output 30 H choke 350 -0 -350 V 1 2 1 Mohm 3 4 7 6 5 0. 47 u. F 9 Gnd Out In Unused Alps stereo pot 1 8 2 7 3 6 5 4 Wiring of In/Out circuitry

L / R Input 3. 15 -0 -3. 15 V L / R Output 30 H choke 350 -0 -350 V 1 2 3 4 7 6 5 10 kohm 470 ohm paralleld with 470 u. F 9 Gnd Out In Unused Alps stereo pot 3. 15 -0 -3. 15 V 1 8 2 7 3 6 5 4 470 ohm paralleld with 470 u. F Wiring of signal circuitry