Hitachi HA-3700 RIAA Preamplifier

The HA-3700 has a wonderful RIAA preamplifier equaliser with 2.5-mV (47-kΩ impedance) sensitivity. The service manual has a circuit diagram showing the design of one using the HA12017 integrated circuit (IC). Interestingly, the preamplifier circuit for the HA-4700 amplifier has switch control for moving magnet (MM) and moving coil (MC) types, however this option is lacking in the HA-3700.

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