PPP HiFi Valve Power Amplifier
using KT88 valves

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Component list
with KT 88 or 6550A
Resistors:
(unless otherwise stated, use metal film types, 0.7W, 1% tolerance; MO = Metal oxide, 5% tolerance)
R1,R2 = 68kOhm
R3 = 2kOhm 2
R4 = 150kOhm , MO, 2W
R5 = 2kOhm 7, MO 2W
R6 = 2kOhm 2
R7 = 1MOhm
R8 = 2kOhm 7
R9 = 22kOhm , MO, 2W
R10 = 390kOhm
R11,R12 = 47kOhm , MO, 2W
R13 = 2kOhm 7, MO, 2W
R14 = 33kOhm
R15,R16 = 10kOhm , MO, 2W
R17,R18 = 10kOhm
R19,R20 = 220kOhm
R21,R22 = 33kOhm
R23,R24 = 3kOhm 3
R25,R26 = 10Ohm , MO, 2W
R27,R28 = 270Ohm , MO, 2W
R29,R30 = 47Ohm
P1,P2 = preset 25kOhm
Capacitors:
C1 = 2µ F2 50V bipolar
C2 = 10pFceramic
C3 = 100pF ceramic
C4,C5 = 47µ F 450V axial
C6 = 10-33pF (fit only if parasitic oscillation is noticed)
C7,C8,C9 = 0µ F22 630V, MKS 4
C10 = 10µ F 100V, lead pitch 5mm
C11-C14 = 47µ F 100V, lead pitch 5mm
C15 = 1nF, MKH, lead pitch 7.5mm (see text)
Semiconductors:
D1 = zener diode 56V 1.3W
D2-D4 = zener diode 110V 1.3 W
D5,D6 = 1N4007
Miscellaneous:
V1 (Rö1) = ECC83
V2 (Rö2) = ECC81
V4 (Rö4),V5 (Rö5) = KT88 or 6550 A
Tr1 (Ü1) = E-1220 (if necessary)
Tr2 (Ü2) = AP-234
2 off 'Noval' (9-way) valve socket, PCB mount
2 off 'Octal' valve socket, PCB mount
Tr1 = Mains transformer NTR-P\7 (Mono) or NTR-P\5 (Stereo)
COMPONENTS LIST
Power Output Stage with EL 34
Resistors:
(unless otherwise stated, use metal film types, 0.7W, 1% tolerance; MO = Metal oxide, 5% tolerance)
R1,R2 = 68kOhm
R3 = 2kOhm 2
R4 = 150kOhm , MO, 2W
R5 = 2kOhm 7, MO, 2W
R6 = 2kOhm 2
R7 = 1MOhm
R8 = 2kOhm 7
R9 = 47kOhm , MO, 2W
R10 = 220kOhm
R11,R12 = 47kOhm , MO, 2W
R13 = 2kOhm 7, MO, 2W
R14 = 33kOhm
R15,R16 = 10kOhm , MO, 2W
R17,R18 = 22kOhm
R19,R20 = 220kOhm
R21,R22 = 33kOhm
R23,R24 = 10kOhm
R25,R26 = 10Ohm , MO, 2W
R27,R28 =150Ohm , MO, 2W
R29,R30 = 47Ohm
P1,P2 = preset 25 kOhm
Capacitors:
C1 = 2µ F2 50
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