Stereo Tube Amplifier Circuit

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.

Circuit diagram

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

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.

author:Weslee Kinsler,