Stereo Tube Amplifier

The circuit is simple, yet is capable of excellent performance. I designed it specifically for use as an amplifier for the digital sound card in my computer. Audio input can be from any two-channel line level device such as a television, CD player, or VCR. It is of the tube type, using only 5 tubes total with no more than about 45 Watts power consumption from the outlet. It uses 3 types of tube 1 5Y3 GT vacuum rectifier, 2 6SF5 GT high-mu triodes, and 2 6K6 power beam amplifiers. These are all full-size octal type tubes which are commonly available today for between $3-5 each.

Schematic

Parts

Part Total Qty. Description Substitutions R1, R10, R13 6 2.2Meg Pot R2 2 470K 1/2W Resistor R3 2 1 Meg 1/2W Resistor R4 2 220K 1/2W Resistor R5 2 330 Ohm 2W Resistor R6 2 220K 1/2W Resistor R7 2 2.2Meg 1/2W Resistor R8 2 1Meg 1/2W Resistor R9 1 720 Ohm 20W Resistor R11 2 33K 1/2W Resistor R12 2 22K 1/2W Resistor C1, C9 4 0.005uF 400V Capacitor C2 2 0.05uF 600V Capacitor C3 2 20uF 25V Electrolytic Capacitor C4 2 0.01uF 400V Capacitor C5 2 200uuF 400V Ceramic Disc Capacitor C6, C7 2 15uF 450V Capacitor C8 2 15uF 400V Capacitor T1 1 117V Primary, 350VCT Secondary, 6.3V Secondary, 6.3V Secondary T2 2 7600 Ohm Primary, 4 or 8 Ohm Secondary SW1 1 SPST Switch SP1, SP2 2 12" or smaller, 4 or 8 ohm speakers MISC 1 5 tube sockets, 2 RCA jacks, PC board or chassis, wire, knobs, etc.

Notes

1. Email Weslee Kinsler with questions, comments, etc.
2. The 6V6 GT tube may be substituted for the 6K6 to lower power requirements.
3. C8 is for radio interference suppression and may be omitted.
4. The 5Y3 GT tube should be mounted in a vertical position and be well ventilated. The 6K6 and 6SF5 tubes can be mounted in any position.
5. Controls should have an audio taper.
6. The power supply portion of this unit may be used for anything requiring 290-320v DC up to about 3 amps.
7. The author has provided a link to an updated version of this circuit. The newer revision contains parts changes based on the author's tinkering and experience with the circuit over the past few years.