JBL 4340 (1975–1980s)
The 4340 was JBL's large-format four-way studio monitor, introduced in 1975 as the middle model in the flagship 4300 series, above the 4343 and below the 4345. It's a big, heavy floor-standing cabinet, about 100 lbs, built for professional control rooms. It found plenty of use in recording studios through the late Seventies and into the Eighties.
The 4340 has five drivers, and each band gets its own. A 15" LE15H woofer, a 10" 2110 mid-bass and a 5" LE5-12 upper-midrange cover the bottom and middle. Two slot tweeters, the 077 and the 2405, handle high frequencies and ultra-highs respectively. Crossover points sit at 150 Hz, 1.5 kHz, and 7.5 kHz, with the 2405 taking over the very top end. The front baffle carries attenuators for both the high-frequency and UHF drivers, so engineers could tailor the top end to their room. Studio users valued that. Impedance is 8 ohms, and JBL recommended serious power, on the order of 200-400 watts per channel.
The 4340 was never cheap, and it isn't cheap now. Well-maintained pairs typically list between $3,000 and $6,000+, and buyers strongly prefer matched original pairs with serial numbers. The usual vintage-JBL problems apply. Foam surrounds on the 10" mid-bass drivers deteriorate, replacements for the LE5-12 midrange are hard to source, and the original crossover capacitors are often out of spec by now. Early units also lack the cabinet bracing of later production, so some owners add bracing to tighten up the enclosures.
Documentation on the 4340 is thin. There's no original price, no published frequency response or sensitivity figures, and no formal press reviews from the period have surfaced. A period survey of monitor loudspeakers noted a comparable JBL model's frequency response of 2.25 dB 30 Hz - 15 kHz with less than .5% T.H.D. Recording Engineer (June 1974, p.58). What's known comes largely from owner experience and forum discussion. That discussion consistently describes the 4340 as capable of very high output without strain, with strong bass and a detailed midrange. It's often called undervalued next to its more famous siblings, though prices have been climbing.
Known specs:
- 4-way floor-standing studio monitor, 5 drivers
- LE15H 15" woofer, 2110 10" mid-bass, LE5-12 5" upper-mid, 077 and 2405 slot tweeters
- Crossover points: 150 Hz, 1.5 kHz, 7.5 kHz
- Impedance: 8 ohms
- Weight: ~100 lbs
- Recommended amplification: 200–400W per channel
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