JBL 4520 (Early 1980s)
The JBL 4520 is a big, serious professional loudspeaker from the early 1980s. It was the largest cabinet in JBL's SR (Sound Reinforcement) series. It was offered as a factory-assembled system with two 15-inch E-155 woofers and a 1-inch 2445J compression driver on a 2344A biradial horn. The crossover is a 1200 Hz "P" type, model N-1200. It's a horn-loaded two-way design with a dual 15-inch bass bin. The enthusiast record describes that bin variously as a "horn bin scoop," a "ported cabinet," and a "dual bass reflex / bandpass" arrangement. The sources genuinely disagree on the loading, so take the exact bass technology with a grain of salt.
Here is what's documented and consistent. Impedance is 8 ohms nominal. Power handling is 125W continuous / 300W peak. Sensitivity is a very high 115 dB (1W/1m), so it was built to get loud with modest power. The enclosure is large at 1050 mm high, 520 mm wide and 440 mm deep, and it weighs 63.5 kg. It's finished in black textured vinyl, with 5-way binding posts for connection. The Sound and Communication (April 1986, p.45) magazine article on disco sound systems discusses the high-output club installs of the era. The 4520 fits that world. These were pro sound-reinforcement tools, not living-room hi-fi.
Enthusiast commentary on forums is split in an instructive way: some users find them lacking in deep low-bass extension compared to reflex designs, while others note they make an excellent platform for a DIY surround system if you have substantial power available. No original retail price, no precise production run dates, and no frequency response spec beyond the crossover point have surfaced in the available record. It's a known quantity among JBL pros and collectors, but the paper trail is thin.
- Type: Horn-loaded two-way, professional sound reinforcement
- LF: 2 × 15" E-155 drivers · HF: 1" 2445J on 2344A biradial horn
- Crossover: N-1200, "P" type, 1200 Hz
- Impedance: 8 ohms · Sensitivity: 115 dB (1W/1m)
- Power: 125W continuous / 300W peak
- Dimensions: 1050 × 520 × 440 mm · Weight: 63.5 kg
- Finish: Black textured vinyl · Connections: 5-way binding posts
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