JBL 4331B/4331BWX (c. 1981)

The 4331B is the successor to the 4331A, part of JBL's professional 43XX series of studio monitors. It's a 2-way, 2-speaker bass reflex system in a large bookshelf-style enclosure. It came in two finishes: the 4331B in gray and the 4331BWX in walnut. In 1981 they were priced at around ¥450,000 and ¥470,000 per unit respectively.

The low end is handled by a 38cm cone woofer, the 2231H. JBL gave it a newly developed cone paper and an edgewise-rolled copper ribbon voice coil for high-input durability. The highs come from a horn assembly built from the 2312 horn, the 2308 acoustic lens and the 2420 compression driver. The lens improves directivity. The crossover sits at 800Hz. You can run the network through the built-in passive crossover, or bi-amp it with a 2-channel multi-amp drive.

Known specifications:

- Frequency response: 35 Hz - 15 kHz ± 3 dB

- Impedance: 8 Ω

- Output sound pressure level: 93 dB/W/m

- Allowable input: 75W (network / below 800 Hz), 30W (above 800 Hz)

- Enclosure volume: 156L

- Dimensions: 619 × 778 × 497 mm (W×H×D)

- Weight: 58.5 kg

Documentation on this model is thin. No period reviews or detailed measurements have surfaced, and production dates are only approximate. What's clear is where it sits in the 43XX lineage, between the 4331A and the 4333A in JBL's professional lineup. Some collectors modify the 4331B into a 4333B configuration by adding supertweeters. Forums and resale listings have noted this conversion.

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