NO_COMPROMISE_PHONO_PREAMP

Published:2009/7/6 1:31:00 Author:May | From:SeekIC

Distortion figure is below 0.002 percent, overload margin is about 47 dB, and S/N ratio is 71 dB for phono amplifier. This feeds normalization amplifier whose output is set at 0 dBm by setting input gain control. Feedback components R2, R3, and C2 provide RIAA bass boost. Tone-control circuit is based on Baxandall system but has bass control turnover frequency which decreases as control approaches flat position. This allows small amount of boost at low end of audio spectrum to correct for transducer shortcomings. Article describes circuit operation in detail and gives additional circuits used for tape output, level detection, noise gate, and power supply. Transistors Tr1-Tr6 and Tr13-Tr15 are BCY71; Tr7-Tr9 and Tr16-Tr18 are MPS A06; Tr10-Tr12 and Tr19-Tr21 are MPS A56; Tr9 is BFX85 or equivalent. Circuit is duplicated for other stereo channel,-D. Self, Advanced Preamplifier Design, Wireless World, Nov. 1976, p 41-46.



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