Hi Fi Stereo Amplifier SM-30

Sansui Electric Co., Ltd.; Tokyo

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  • Year
  • 1960 ?
  • Category
  • Broadcast Receiver - or past WW2 Tuner
  • Radiomuseum.org ID
  • 366859

Click on the schematic thumbnail to request the schematic as a free document.

 Technical Specifications

  • Number of Tubes
  • 23
  • Number of Transistors
  • Main principle
  • Superheterodyne (common)
  • Wave bands
  • Broadcast, Short Wave plus FM or UHF.
  • Power type and voltage
  • Alternating Current supply (AC) / 100; 117 Volt
  • Loudspeaker
  • - This model requires external speaker(s).
  • Material
  • Metal case
  • from Radiomuseum.org
  • Model: Hi Fi Stereo Amplifier SM-30 - Sansui Electric Co., Ltd.;
  • Shape
  • Book-shelf unit.
  • Notes

  • Hi Fi Stereo Amplifier SM-30

    Stereo vacuum‑tube amplifier with mono FM and MW/SW AM tuner. Hybrid construction: vacuum‑tube RF/IF and power‑amplifier stages with transistorised low‑level preamplifier circuits. FM stereo requires an external multiplex (MPX) decoder connected via the rear RCA MPX IN/OUT jacks.

    The tuner includes two AM tuning sections, each with its own tuning capacitor. The second AM chain provides a buffered AM detector output on the rear panel for recording and alignment; it is not a separate AM program tuner. FM employs a 10.7 MHz IF strip with ratio detector and switchable AFC.

    Two 6DA5 tuning‑indicator tubes provide separate visual indication for AM and FM tuning accuracy.

    Audio output is stereo, using push‑pull 6BM8 (ECL82) pentodes per channel with fixed bias. Tone controls are passive. Low‑level phono and tape‑head stages use germanium transistors.

    Rear‑panel signal connections include:
    Three screw‑terminal outputs:

    • AM‑Ch.1 (AM IF)
    • FM (FM IF)
    • AM‑Ch.2 (AM detector output; audio level)

    RCA jacks:

    • MPX IN/ OUT
    • TAPE REC
    • AUX
    • MIC
    • X-TAL
    • MAG TAPE

    Construction is point‑to‑point with Sansui‑made transformers.

    Related model: Sansui SM‑33, which uses the same dual‑AM architecture and MPX facilities but provides only IF‑level AM outputs on the rear panel and uses dual magic‑eye indicator instead of 6DA5 tuning tubes.

  • Mentioned in
  • -- Schematic

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