Denon SC-104 (1970s)

The Denon SC-104 is a sealed (airtight) 3-way bookshelf speaker from the 1970s, developed through a technical tie-up with Peerless of Denmark. It was priced at ¥39,800 per unit around 1975. A later price of ¥43,800 is recorded around 1977. The cabinet is 18mm particle board with real walnut veneer on both sides. Each speaker weighs 13.8kg, which is a lot for a bookshelf box.

The drivers are a 25cm cone woofer, a 10cm cone midrange and a 3.2cm dome tweeter. The woofer has a light, strong cone paper, a foamed polyurethane roll edge treated with damping material, and an aluminum bobbin drive assembly. The midrange uses non-pressed cone paper with a damped back coating. Its back cavity and frame are made as one piece in light alloy diecasting, to resist intermodulation distortion from woofer vibrations, and the cavity is filled with ring-shaped glass wool. The tweeter has a specially developed cloth diaphragm with a small effective diameter, for good dispersion and flat power response. Crossover points are 500 Hz and 4 kHz, with continuously variable level controls for mid and high frequencies. The woofer circuit uses a ferrite bobbin coil to keep DC resistance low. Everything else gets air-core coils, and plane foil capacitors keep tolerances tight. The sealed enclosure is mounted with butyl-based putty to suppress cabinet vibration. Input is via screw-type terminals.

Rated specs are 60W maximum input (program source), frequency response of 50 Hz to 20 kHz, 8Ω impedance, 92dB/W/m mean output sound pressure, and total harmonic distortion of 1.5% or less at 5W (100 Hz and above). Dimensions are 302mm wide, 590mm high and 257mm deep.

A second variant, the SC-104/Ⅱ, is known to exist, though its specifications are not separately documented. Japanese sources call the SC-104 a "famous model" among sealed bookshelf speakers of its era, with solid cabinet construction and careful finishing. A 2017 buyout appraisal valued a pair at ¥50,000. Surviving examples turn up on the Japanese secondhand market from time to time, often listed as rare. Audio-Collection (via audio-database.com) documents the full specifications and the Peerless tie-up.