JBL SR4731A (c. 1994)

The SR4731A is a professional two-way bass reflex speaker from JBL's SR series. It was made for live sound, not home hi-fi. The box is big and heavy - 635 mm wide, 1,092 mm tall, 460 mm deep, and 55.4 kg. It was built to work as a main system in small and medium halls, as a main PA, as side fills, or in rehearsal studios. The Japanese-market price was ¥320,000 per unit around 1994, and ¥299,000 by around 1997.

Two 30 cm cone woofers (model 2206H) handle the low band. The highs come from a horn-loaded driver, a 2447J compression driver on a 2381 horn, which gives a 90° horizontal by 50° vertical dispersion pattern. The load is 4 ohms nominal, with a rated sound pressure level of 99 dB/W/m. Frequency characteristic is specified at 40 Hz to 18 kHz (-10 dB). The internal crossover is set at 1.2 kHz, though JBL recommends 1.3-1.5 kHz for multi-amplified use. The speaker has a built-in network and a multi-amplifier drive switch for that purpose. Bi-amped, the LF section is rated at 1,200W into 4 ohms and the HF section at 150W into 16 ohms.

Documentation on this model is thin. Most of the hard specs trace back to a single Japanese database entry, and there's no period review coverage in the usual hi-fi press. This was professional gear, not a consumer product, and it seems to have flown under the enthusiast radar. What survives in the wild comes mostly from working sound people. One is a forum post from someone prepping to bi-amp a pair and asking about the input panel (the answer didn't get recorded). Another is a used sale listing for boxes that had been "de-rat-furred," coated with bedliner, fitted with custom grilles, and freshly reconed 2206s, sold as "great lo-budget side fills" for $600. A second used listing on SoundBroker offered units individually, with two available at the time.

Spare parts do surface occasionally. The network assembly (part number 75644-01) and crossover network appear in parts listings, which suggests people are keeping these running rather than scrapping them. What the "A" suffix changes versus the non-"A" SR4731 isn't documented anywhere on record, and production years beyond the price data points aren't recorded either.

Known specs, in brief:

- 2-way, 3-speaker, bass reflex, floor type

- LF: 30 cm cone (2206H) ×2; HF: horn (2447J + 2381)

- Frequency response: 40 Hz - 18 kHz (-10 dB)

- Nominal impedance: 4 Ω

- SPL: 99 dB/W/m

- Crossover: 1.2 kHz (internal); 1.3-1.5 kHz recommended for multi-amp

- Power handling: 1,200W continuous pink noise (full range); LF 1,200W/4 Ω, HF 150W/16 Ω

- Dimensions: 635 × 1,092 × 460 mm; 55.4 kg

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