JBL SR4725A (circa 1994–1997)
The JBL SR4725A is a professional two-way, bass-reflex loudspeaker from the SR Series. By the late 1990s that line was considered top of the line among JBL's portable PA offerings. It's the most common configuration in the SR4725 family. In Japan it sold at ¥210,000 per unit around 1994, dropping to ¥195,000 by around 1997.
The driver complement is a serious one. The low end is handled by JBL's 38 cm (15") 2226H woofer, which uses the company's VGC (Vented Gap Cooling) system to keep the voice coil cool under sustained high-power use. High frequencies come from a 2426H compression driver mounted on a flat-front biradial 2370A horn, giving 90° horizontal by 40° vertical coverage. The system is rated at 600W continuous pink noise (IEC), with a sensitivity of 97 dB/W/m and a frequency response of 35 Hz to 18 kHz at -10 dB. Nominal impedance is 8 ohms, and the crossover sits at 1.1 kHz.
The cabinet is trapezoidal, finished in gray, and weighs 35.9 kg. It's a professional box, so it's designed to be suspended. The manual carries a caution that rigging should only be done by qualified persons following safe rigging standards, noting that "the weakest component determines the size and safety of the entire array." Inputs are 1/4" and Speakon.
The SR4725A includes a built-in network and a 2-way multi-amplifier drive changeover switch, so it can run either full-range or bi-amped. When run bi-amped, JBL recommends a crossover between 1.2 kHz and 1.4 kHz, with the low section accepting 600W/8Ω and the high section 100W/8Ω.
The documented record on these is mostly practical rather than critical. Owners describe them as reliable workhorses - "they sound great, never any problems" is a typical sentiment - and they remain in service for churches, bands, and home use. A common failure point, unsurprisingly for a PA speaker, is the compression driver diaphragm. At least one owner reports frying diaphragms after a microphone was dropped into the horn, and replacing them is a known repair. Finding the crossover inside the cabinet has also confused at least one owner, who noted it wasn't obviously visible without digging into the hotmelt adhesive.
Period reviews in the strict hi-fi press are essentially nonexistent. This is a professional sound reinforcement tool, not a living-room monitor, so it stayed out of Audio and High Fidelity reviewing. The record does show a speaker that was bought new in the mid-1990s, powered by QSC amplifiers in full-range mode, and still working fine decades later. Used prices vary widely. One Russian listing asks 80,000 ₽, a U.S. seller wants $500 OBO, and a Korean listing notes external wear with all drivers functioning normally.
- Type: 2-way, 2-speaker, bass-reflex
- LF: 38 cm (15") 2226H woofer with VGC
- HF: 2426H driver on 2370A biradial horn (90°H × 40°V)
- Frequency response: 35 Hz – 18 kHz (−10 dB)
- Input rating: 600W continuous pink noise (IEC)
- Impedance: 8 Ω
- Sensitivity: 97 dB/W/m
- Crossover: 1.1 kHz (full-range); 1.2–1.4 kHz recommended for bi-amp
- Dimensions: 635 × 749 × 460 mm (W×H×D)
- Weight: 35.9 kg
- Inputs: 1/4" and Speakon
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