This is PA amp with Hi-Fi sound, simple circuit on small pcb with very high-performanse, For stereo B500 use 1500W transformer sec: 2x60v + 2x18v for protect circuit. Fans 2x12v conect in series one on front second on back side amp. DC offset under 20mV is OK If you want to use B500 as Hi-Fi amp, I suggest to adjust BIAS current to about 30-50mA per outputs. MJE340/MJE350 must have heatsinks, VAS current can be increase with useing 680R instead 1k for R15,R16 For B500 2x60vAC max, but I suggest 2x55vAC for safety operate + 2x18v for protect circuit. Use two caps 20,000uF/75V with transformer 1500W 2x50VAC sec for stereo. Amp will stable at 2ohms load, but with +/-50V DC rail voltage, or with add more outputs B500 based on schematics of H900, but in AB class. Power supply +/-90Vmax. NSL32 can be replaced with 47k resistor and LED for 'clip' indicate, if you don't want use limiter, MJE340/MJE350 need some small heatsink. 2N5401/2N5551 can be substituited with MPSA92/MPSA42 2SC4793/2SA1837 can replace MJE340/MJE350 R24 R25 summary +/-40v dc 1k2 2w +/-55 1k5 +/-80 2k2 +/-90v dc 4k7 2w
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