Class AB1; Power Output, 15 Watts
This circuit was found in the RCA Receiving tube Manual, 1970 edition.
Circuit Description
This high-fidelity audio power amplifier can deliver 15 watts of ms output power with less than 0.4 per cent total harmonic distortion and less than 1.5 per cent intermodulation distortion.
The frequency response of the amplifier is flat within 10.5 dB from 20 Hz to 60 kHz, and the sensitivity is such that the rated output of 15 watts is obtained for an input of 1.2 volts ms.
The total hum and noise, with the input shorted, is 84 dB below 15 watts.
The circuit operates from a 117-volt ac power line.
The transformer-coupled ac input power is converted to dc operating.
C1 - 40 µF, electrolytic. 450 V.
C2, C4, C5 - 0.25 µF, paper. 400 V.
C3 -- 3.3 pF, ceramic or mica. 600 V
C6 -150 pF", ceramic or mica 400 V.
C7. C8 - :0.05 µF. paper 400 V.
C9 - :0.02 µF. paper 600 V.
C10 – 100 µF. electrolytic,
C11- 80 µF electrolytic, 450 C
C12 – 40 µF . electrolytic.
F1=Fuse. 3 ampere:
L1=Choke. 3 H, 160 mA. Dc resistance 75 ohm: or less,
R1=Volume control. potentiometer. 1 megohm
R2=10000 Ω. 0.6 watt
R3=0.82 megohm. 0.5 watt
R4 =820 Ω, 0.5 wntt
R5=0.22 megohm. 0.5 watt
R6, R7=15000 ohm :5 per cent. 2 watts
R8=3900 Ω. 2 watts
R9, R10 = 0.1 megohm, 0.5 watt
R11. R12-1000 Ω, 0.5 watt
R13, R14 -1100 Ω. 0.5 watt
R15 -8200 Ω. 0.5 watt
R16=15000 Ω, 1 watt
R17 -68000 Ω. 0.5 watt
R18 - 4700 Ω. 2 watts
R19 -0.27 megohm, 1 watt
R20 =47000 Ω, 0.5 watt
R21=Hum balance adjustment potentiometer, 100 Ω, 0.5 wntt
SR1=Selenium rectifier.,20 mA, 135 volts rms
T1=output transformer. (having 8-ohm up for feed-back connection) for matching impedance of voice coil to 6600-ohm plate-to-plate, tube loud; 50 watts: frequency response. 10 to 50000 Hz:
T2=Power transformer. 360-0-360 volts rms. 120 mA; 6.3 V., 3.5 A; 5 V., 3 A:
