This is one of Pioneer's unique products - the Pioneer RG-9 is an analog dynamic audio processor produced during the classic Hi-Fi era. It is designed to expand and control the dynamic range of audio signals, making music sound more lively and expressive without conventional compression. Purpose Dynamic range expander / processor Enhances perceived dynamics by: Raising low-level signals Controlling high-level peaks Intended to restore dynamics lost in recordings or playback chains Signal Path Line-level audio device Installed between preamplifier and power amplifier (or via tape loop) Compatible with standard Hi-Fi components Key Functions Dynamic Expansion Control Adjustable expansion level Attack / Release Control Controls how fast the processor responds to signal changes Gain Control Maintains proper output level after processing Bypass / Defeat Mode Allows direct comparison with unprocessed signal Technical Specifications (typical) Frequency response: Approx. 20 Hz – 20 kHz Total Harmonic Distortion (THD): ~0.05% at 1 kHz Input level: Line level (approx. 300 mV nominal) Output level: Line level (up to ~1 V) Signal-to-noise ratio: High for analog Hi-Fi equipment of its era Power supply: AC mains (region-specific voltage) Physical Characteristics: Dimensions: Approx. 420 mm (W) × 99 mm (H) × 336 mm (D) Weight: Approx. 4.4 kg Front panel: Aluminum shampagne colour with rotary knobs and indicator LEDs Typical Use Cases Vintage Hi-Fi systems Improving dynamics of: FM radio broadcasts Vinyl records Cassette tapes Listening environments where recordings sound flat or compressed Summary The Pioneer RG-9 is a dynamic expander, not an equalizer or amplifier Designed to enhance musical realism and punch fully analog, low-distortion Hi-Fi component Best used subtly for natural sound improvement NB! See photos for physical condition (there some small scratches and small damages from use or transportation. It has no impact on sound quality.