PIONEER SX-424 is a AM/FM solid state stereo receiver, manufactured in 1970. The output power is rated at 12w per channel into 8 ohms. The frequency response is 20hz to 70khz and total harmonic distortion is 1%. It’s a budget-priced AM/FM stereo receiver with special features for sensitive FM tuning and wide frequency response. The sources are records, tape, FM and microphone. The speaker output impedance is from 4Ω to 16Ω.