Mugen: A Hybrid Audio Amplifier
The best of both worlds?
Valves (or ‘vacuum tubes’) are experiencing a real revival in the audio world, which can readily be seen from the large number of commercial amplifiers and DIY designs that have appeared in recent years.
Unfortunately, valve amplifiers are relatively costly compared withtransistor amplifiers, in part due to the need for a high voltage supply and output transformers. Output transformers in particular are a major investment.
This design attempts to remedy this situation by replacing the output valves and transformer.
Materials
Extra info / Update
5 February 2008.
In the parts list, the value of R11 is erroneously given as 18 ohm. The correct value is 18 kohm.
The correction has been incorporated in the parts list on the project web pagee.
Component list
amplifier & power supply
(for a stereo version, all components must be purchased double)
Resistors
(1% metal film, 600mW unless other rating indicated)
R1 = 392k
R2,R5,R12,R20,R32 = 1k
R3,R4 = 150kΩ 2W (BC PR02 series)
R6,R15,R19,R45 = 100(
R7 = 22kΩ 3W (BCPR03 series)
R8 = 2kΩ43
R9 = 274(
R10 = 560(
R11 = 18k(
R13,R17 = 392(
R14,R18 = 2Ω2
R16 = 20k
R21,R22 = 0Ω22 4W (Intertechnik MOX)
R23 = 10( 2W
R24,R26 = 182(
R25 = 1kΩ5
R27 = 3kΩ3
R28,R29 = 1M
R30 = 330k
R31 = 10M
R33, R34, R35 = 100k
R36 = to be determined (0.22( using 3N604)
R37,R38 = 100( 1W (see text)
R39 = 330(
R40 = 82kΩ 3W
R41 = 150kΩ 3W
R42,R43 = 1kΩ 1W
R44 = 4Ω7
P1 = 2kΩ,15-turn preset, T93YB (Vishay) or 3296Y (Bourns)
P2,P3 = 5kΩ,15-turn preset, T93YB (Vishay) or 3296Y (Bourns)
Capacitors
C1 = 100nF 400VDC
C2,C3 = 3(F3 400VDC (ClarityCap SA 630 V audiograde capacitor)
C4,C6,C8,C10 = 270(F 50V (Panasonic FC, Farnell # 9692436)
C5,C9,C12,C14,C22 = 100nF 50V
C7 = 100nF (Vishay MKP-1834, Farnell # 1166887)
C11,C16,C17 = 10(F 50V
C13 = 47(F 50V
C15 = 1(F 250V (e.g. Wima foil capacitor, see text)
C18 = 22(F 63V
C19,C20 = 47(F 25V
C21 = 220(F 50V
C23 = 2nF2 (Wima FKP-1/700 VAC, see text)
C29,C30,C31,C35 = 2nF2 (Wima FKP-1/ 700 VAC)
C24 = 150(F 450V
C25 = 100nF 450 VDC
C26 = 10(F 400V
C27,C28 = 22(F 400V
C32,C33,C34,C36,C37,C38 = 4700 (F 63V (BC056, 30x40 mm, Conrad Electronics # 446286-89)
C39 = 10(F 25V
Cfb = 56pF (optional)
Semiconductors
D1 = not used
D2,D3 = UF4007 (if necc. 1N4007)
D4,D5 = 1N4001
D6,D7,D8 = 1N4148
D9,D10,D11,D12 = BY228
D13 = 1N4007
LED1 = LED, 5mm, red
Z1 = zener diode 110V 1.3W
Q1 = BD139
Q2 = 2SC2073
Q3 = 2SA940
Q4,Q5 = 2SC5200
Q6,Q7 = BC550B
Q8 = BS170
Q9,Q10 = BC547B
Qbax = 2SC1815BL
U1 = LM337
U2 = LM317
U3 = TL783 (Conrad Electronics # 175012-62)
Valves
V1 = ECC83 (pref. JJ Electronics)
V2 = ECC88 (pref. JJ Electronics)
Miscellaneous
B1 = bridge rectifier 600 V piv @1A (DF06M)
B2,B3 = bridge rectifier 400V piv @ 35A
T1 = mains transformer, sec. 30V + 250V + 6.3V (Amplimo type 3N604)
T2 = mains transformer, sec. 2x28 VAC, 300VA (Amplimo type 78057)
RLY1 = output relay 24V (e.g. Amplimo type LR)
Heatsink profile for U3 (Fischer SK104 25,4 STC-220 14K/W (e.g. Conrad Electronics # 186140-62)
Heatsink profile for U1 and U2, Fischer FK137 SA 220, 21K/W (e.g. Conrad Electronics # 188565-62)
Heatsink profile for Q4 and Q5, 0.7K/W or better
9-way valve socket (Noval), PCB mount, for V1 and V2
Amplifier board, no. 070069-1 (mono)
Supply board, no. 070069-2
Suggested suppliers
Toroidal transformers and output relay:
ClarityCap SA capacitors:
(OEM like Soniqs SAX)
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