|
This circuit is quite simple, making it ideal for a DIY project. The cost-benefit ratio is excellent.
Sansui Eight Phono Preamp Section
The Sansui Eight (produced around 1970–1972) is one of Sansui’s classic solid-state receivers, highly regarded for both its tuner section and its amplifier stage. Its phono preamp section was quite advanced for its time, reflecting Sansui’s ambition to compete with Marantz and McIntosh. Here are the main technical and design points about it:
⸻
1. Circuit Topology
• The Eight’s phono stage is a discrete transistor RIAA equalizer, not IC-based (IC phono preamps didn’t appear until later in the 70s).
• Uses low-noise silicon transistors arranged in a three-stage configuration with negative feedback for accuracy.
• The RIAA equalization is done via a feedback network, giving better linearity than passive equalization.
• Sansui paid attention to channel separation and grounding to reduce hum and crosstalk.
⸻
2. Performance Specs (typical values for the Eight)
• Phono Sensitivity: ~2.5 mV (for rated output).
• Input Impedance: 47 kΩ (standard for MM cartridges).
• S/N Ratio: around 70 dB (very good for early 70s solid-state).
• THD: < 0.5% in the phono section.
• RIAA accuracy: within ±0.5 dB from 30 Hz to 15 kHz.
⸻
3. Sound Character
• Warm yet detailed, a bit smoother than later Sansui units (like the AU-717, which leaned more toward neutral and punchy).
• Well-suited for MM cartridges of the era (Shure, Pickering, Stanton, Empire, Audio-Technica).
• Bass is solid, mids are warm, treble has a touch of sweetness rather than clinical brightness.
|
