I propose you here a basic MOSFET
amplifier. Output power is +/- 100 Wrms under 8 ohms or +/- 160 Wrms under 4 ohms.
Due to the circuit simplicity, distortion is +/- 0.1 %. Bandwidth at -3 db is from 4 Hz to 96 Khz, it is limited by C1, R1, C2 and R2.
Circuit Mosfet Amplifier 2SK1530
Transistors T1 and T2 makes a first differential stage, current source of +/- 1 mA is set by R3. In the upgraded version, current source is more efficient in stability. P1 allows a fine tuning of DC voltage at amplifier’s output. Place P1 at it’s half value for first power up, then turn it slowly for a lowest DC output voltage. Use a first quality compoment.
C1 = 2,2 µF MKP, MKT 100 V
C2 = 330 pF ceramique 50 V
C3 = 100 nF MKP, MKT 100 V
C4 = 100 µF 40 V electro-chimique
C5, C6 = 18pF ceramique 50 V
C7 = 100 nF MKP, MKT 250 V (C8 = 47µF 100 V)
R1, R3 = 47 K (R3 = 330 – 470 Ohms)
R2 = 2K2
R4, R5 = 3K9
R6 = 1 K
R7 = 27 K
R8, R9, R11 = 100 ohms
R10 = 10 K
R12, R13 = 470 ohms
R14, R15 = 0.33 ohms 5 watts
R16 = 10 ohms 3 watts (R17 = 1 K R18, R19 = 10K)
T1, T2, T9,T10 = 2N5401, ZTX558, BC556B (attention au brochage different – take care for pin layout)
T3, T4 = BF470, MJE350, 2SB649
T5, T6 = BF469, MJE340, 2SD669
T7 = IRFP240, 2SK1530, 2SJ162, BUZ900DP, BUZ901DP (attention au brochage different – take care for pin layout : GDS GSD)
T8 = IRFP9240, 2SJ201, 2SK1058, BUZ905DP, BUZ906DP (attention au brochage different – take care for pin layout : GDS GSD)
P1 = 100 ohms (25 tours – 25 turns)
P2 = 2K5 (25 tours – 25 turns)
F1, F2 = 3 A T