JBL 4350/4350WX (1973–c.1975)

The JBL 4350 is a top-of-the-line studio monitor from JBL's professional series, introduced in 1973 and produced until around 1975. JBL built it as its definitive monitor speaker. It is a massive, bi-amplification-only, four-way floor system that weighed 110 kg (some early catalogs list 125 kg) and stood over a meter wide. It ruled professional studios worldwide, and it remains one of the most revered and physically imposing vintage JBL designs.

The 4350 is a 4-way, 5-speaker bass reflex system. Two 38 cm cone woofers (model 2230A) handle the low end. They use JBL's coated cone paper and edgewise-wound ribbon copper voice coils. Above them sits a 30 cm cone mid-woofer (2202A) in its own enclosed 34L sub-chamber, machined to prevent back-wave interference with the woofers. The midrange and highs come from a horn-loaded compression driver - the large-format 2440 mated to a 2311 horn and 2308 acoustic lens. A 2405 ring-type tweeter with a "glass prism" faceplate handles the top octave. The 2440 uses a 0.076 mm aluminum-alloy diaphragm, and the 2405's ring diaphragm is formed from 0.056 mm aluminum foil, extending response to 20 kHz within ±3 dB.

This is a bi-amp-only design. The system is divided at 250 Hz. Below that, the two woofers present a 4 Ω load rated for 200W continuous program. Above 250 Hz the system is 8 Ω and rated for 100W. You need two power amplifiers plus an external electronic crossover - JBL's own 5231 or 5232 divider, or the later 5234/5235 - and a filter board (52-5121). There is no passive crossover for the low end. The mid/high section does use a specially designed L-C network with continuously variable level controls on the front panel. Frequency response is rated at 30 Hz to 20 kHz ±3 dB, with sensitivity of 95.5 dB (New JIS) and distortion under 1% at 108 dB SPL from 33 Hz to 1.2 kHz. The enclosure is built from 20 mm stock and comes in two finishes: gray and walnut (the WX suffix denotes the walnut version). At ¥993,800 per unit (¥1,107,900 for the WX), this was never an impulse buy.

Two appearance variations exist, gray and walnut, and the WX suffix marks the walnut-finished version. The 4350 was priced at 993,800 yen per unit in Japan at launch, with the 4350WX at 1,107,900 yen. One Audio Cynic writer later recalled passing on a pair at $1,150 each brand new, shipped free, and still regrets it. The "blue" JBL professional series, as the 4350 is known in some circles, still occupies prominent places in high-end installations today.

For collectors, the big issues are the 2230A woofer surrounds (both of them - edge rot is common and replacement is costly), the 2440's aluminum diaphragm (which ages), and the 2405 tweeter (which can develop open voice coils). At 110 kg, the cabinets also tend to show bottom-panel sag and corner damage from being moved. A working pair with the original dividers and grilles commands a significant premium. Pairs are worth more than singles, obviously. One listener on StereoNET noted they work best against a back wall, as they were designed for soffit mounting, though you can still sit three meters away in a 6×4 meter room with space to spare.

Surviving documentation is thin on some specifics. There is no original US launch price, no full dimensional spec sheet beyond the 1,210 × 890 × 510 mm footprint, and the distinction between the 4350, 4350A, 4350B, and their WX variants is not clearly defined in any single source.

Known Specifications

• Type: 4-way, 5-speaker, bass reflex, floor-standing monitor
• Drivers: 2× 2230A 38 cm woofers, 2202A 30 cm mid-woofer, 2440 compression driver + 2311 horn + 2308 acoustic lens (mid/high), 2405 ring tweeter
• Frequency response: 30 Hz – 20 kHz ±3 dB
• Crossover: 250 Hz (12 dB/oct), 1.1 kHz, 9 kHz
• Impedance: 4 Ω (below 250 Hz), 8 Ω (above 250 Hz)
• Power handling: 200W (below 250 Hz), 100W (above 250 Hz), continuous program
• Sensitivity: 95.5 dB (New JIS); 110 dB SPL at 10 ft (½ pink noise, allowable input)
• Dimensions: 1,210 × 890 × 510 mm (W × H × D)
• Weight: 110 kg (later catalogs) / 125 kg (1973 catalog)
• Enclosure volume: 269L (including 34L sealed chamber for 2202A)
• Finish: Gray or walnut (WX)

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