AKG K-340 (c. 1980–1992)

The K-340 was AKG's attempt to build a "concert hall of your very own." First advertised in early 1980, it was, by AKG's own claim, the first headphone to combine electrostatic and dynamic transducers together with passive diaphragms (HiFI-Stereo, January 1980, p.43). It came out of intensive psychoacoustic research aimed at simulating the sound of high-quality loudspeakers rather than conventional headphones. The electrostatic element handled the highs and the dynamic driver handled the lows. The passive diaphragms were meant to make the acoustic load behave more like a real room.

The most complete period documentation is in Audio magazine (November 1992, p.108). It reviewed the still-current K-340 at $249 and was clearly impressed, calling it a landmark of acoustic design. The review gives the real specifications: electrostatic tweeter with dynamic woofer; 400-ohm impedance with DC resistance of roughly 318/319 ohms left/right; 117 dB SPL sensitivity for 200 mW input; 7¾-foot coiled cord exiting the left earcup with a ¼-inch stereo plug; headband adjustment via detented bails; weight 14 oz (0.387 kg).

Beyond that, the record is thin. The same hybrid design was still being advertised in 1981 (HiFI-Stereo, 1981, p.96), and a High Fidelity equipment directory (1980, p.194) carried the K-340, so it was clearly a long-lived flagship. Exact production dates, the original launch price, and the end of its run are not documented in the sources available to us. One conflicting 1980 directory entry describes an open-back dynamic headphone at 7 oz. It appears to belong to a different AKG model on the same chart, so ignore those figures for the K-340.

Known Specs

• Hybrid transducer design: electrostatic tweeter, dynamic woofer, passive diaphragms
• Coupling: circumaural
• Impedance: 400 ohms; DC resistance ≈ 318/319 ohms (L/R)
• Sensitivity: 117 dB SPL for 200 mW
• Coiled 7¾-ft cord from left earcup, ¼-inch stereo phone plug
• Weight: 14 oz (0.387 kg)
• Price at 1992 Audio review: $249

eBay Listings

Vintage AKG K-340 Rare High-End Headphones , Excellent Condi

$208

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