JBL MI-631 (ca. 1984)
The JBL MI-631 is a stage monitor speaker system from around 1984. It belongs to JBL's MI series, a line built, in the company's own words, around the concept of "JBL sound for more players." It is a 2-way, 2-speaker bass-reflex design in a floor-type enclosure with a slanted front baffle. The slant points the driver array up at a performer standing close to it.
The low end comes from a 30 cm cone wide-range unit, the MI-12. It uses a low-distortion SFG magnetic circuit and a four-layer voice coil. High frequencies come from a horn-type driver with a titanium diaphragm and diamond suspension, mated to a biradial horn. The crossover sits at 2 kHz. The system is rated at 8 ohms with a 300W continuous program input. Sensitivity is a healthy 100 dB/W/m, the playback band runs 60 Hz to 15 kHz (-10 dB), and dispersion is 90° x 40°. Each cabinet measures 439 x 349 x 535 mm and weighs 21 kg.
The MI-631 was priced at ¥165,000 per unit around 1984. Beyond that, the record is thin. There are no production run dates, no reception or review content, and no corroboration beyond the Japanese audio databases that document it. It is a solidly built, high-output stage wedge from JBL's professional-leaning MI line.
- 2-way, 2-speaker bass-reflex, floor type
- LF: 30 cm cone (MI-12) with SFG magnetic circuit, 4-layer voice coil
- HF: horn type, titanium diaphragm, diamond suspension, biradial horn
- 8 ohms · 300W continuous program · 100 dB/W/m
- Crossover: 2 kHz · 60 Hz - 15 kHz (-10 dB) · 90° x 40° dispersion
- 439 x 349 x 535 mm · 21 kg · ¥165,000 (ca. 1984)
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