JBL 4788A
The JBL 4788A is a professional cinema screen loudspeaker from the company's 4780 Series, a lineup of behind-the-screen systems built for movie theaters. It's a large piece of pro gear: a 4-way system in a black carpeted wood enclosure, designed to sit behind a perforated screen and fill a room with sound. It is not a home hi-fi speaker, and JBL marketed it strictly as commercial equipment.
JBL's own spec sheet calls it a "quadruple 8-inch" system. Four 8-inch low-frequency drivers handle the bottom end. A single 8-inch midrange sits above them, and two 1-inch 2450H compression drivers on constant-directivity horns take the highs. Crossover points are 550 Hz and 2.9 kHz. The system covers 55 Hz to 20 kHz with 91 dB sensitivity (1W/1m) and an 8-ohm nominal impedance. The cabinet is 39 inches tall, 24 inches wide, 18 inches deep, and 115 pounds. Input is a barrier strip, standard for installed cinema systems.
Two independent technical sources agree on every published parameter, which is handy for a model this obscure. What's missing is the human record. No production years, no original price, no period reviews, and no owner feedback have surfaced. The driver complement (2118H and 2450H) comes from the JBL spec sheet table and is not independently corroborated, though both are well-known professional-series parts. The 4788A shows up occasionally on the used market. One dealer listing simply calls it a "JBL 4788A Cinema screen system". Beyond that, the archive is thin.
- Type: 4-way cinema screen system, quadruple 8-inch
- Drivers: 4 × 2118H (8" LF), 1 × 2118H (8" mid), 2 × 2450H (1" HF)
- Frequency range: 55 Hz – 20 kHz
- Sensitivity: 91 dB (1W/1m)
- Impedance: 8 ohms
- Crossover: 550 Hz, 2.9 kHz
- Dimensions (H×W×D): 39.0 × 24.0 × 18.0 in (991 × 610 × 457 mm)
- Weight: 115 lb (52.2 kg)
- Finish: Black carpeted wood; barrier strip input
The 4788A is part of the JBL 4780 Series, which also included 2-way and 3-way models (4780A through 4785A). It was one of the 4-way models in that family, though the relative hierarchy between series models isn't documented. Studio Sound (November 1991, p.20) covered the UK sound rental market that year, but made no mention of this specific model.
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