Onkyo QuartLam-III (circa 1976)
The Onkyo QuartLam-III is a floor-standing speaker from the mid-1970s with an unusual way of making bass. It was sold around 1976 at ¥25,000 per unit. It uses what Onkyo called the QL system, a design built on the principles of the flute and the Japanese Yokobue. There is no conventional enclosure. Instead, an Acoustic Loading Tube (ALT) is mounted at the rear of the cabinet. Sound from the back of the driver resonates in the tube at frequencies corresponding to one-quarter of the tube's length, which reproduces low frequencies efficiently. The driver sits in the middle of this 1.8-meter tube, and the tube sets the lowest resonance frequency at 47.2 Hz, the lower limit of the speaker's range. Onkyo controlled the tube's higher-order resonances by tapering the partition plate, adding sound-absorbing material, and installing a tuning port.
The QuartLam-III is a 2-way, 3-driver design rated for 40W maximum input, with a 94 dB/W/m output sound pressure level and 6 Ω impedance. The low end is handled by a single 16 cm cone woofer (W-1608C). It has light, long-fiber cone paper and a compliant urethane Ω-type roll edge. A large 100 mm magnet drives it, and a 30 mm aluminum-foil voice coil bobbin improves damping. The high range uses two 8 cm cone tweeters (TW-825A and TW-825B), and they are deliberately mismatched. One has a fixed edge and the other a free edge, so their characteristics differ and their response bands overlap in a staggered manner to extend high-frequency reproduction. A rear-mounted level control switches the tweeter output in three steps. In the minimum position, one of the tweeters is cut entirely. Crossover is at 1 kHz, and the network structure is independent per driver. The enclosure is hard particle board with an especially thick front baffle.
Surviving documentation on the QuartLam-III is thin. No production years, reception history, or collector-market data has surfaced. The QL loading approach is the unusual part, and Onkyo derived it from musical instrument acoustics rather than conventional speaker design.
- Type: 2-way, 3-speaker, QL system, floor type
- Playback frequency band: 47 Hz – 20 kHz
- Max input: 40W
- Output sound pressure level: 94 dB/W/m
- Impedance: 6 Ω
- Crossover frequency: 1 kHz
- Dimensions: 240 × 730 × 380 mm (W×H×D); 13.5 kg
- Low-range driver: 16 cm cone (W-1608C)
- High-range drivers: 8 cm cone ×2 (TW-825A, TW-825B)
- Original price: ¥25,000 (1 unit, circa 1976)
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