Наушники — Koss CL-20

The CL-20 is a full-size wired headphone from Koss, the Milwaukee company founded by John C. Koss in 1953 and credited with launching the first consumer stereo headphone in 1958. Its most recognisable feature is a clear, transparent retro-style housing that openly shows the inner workings of the earcups, built around a simple, closed-back dynamic headphone meant for everyday home and desk listening.

Key specs that matter

The CL-20 uses dynamic drivers in a closed-back, over-ear configuration. Frequency response spans 30Hz to 20,000Hz. Sensitivity is 103dB SPL at 1kHz/1mW and impedance is 60 ohms. Connection is through a fixed cable ending in a standard 3.5mm mini-jack plug, and the earcushions are soft, padded leatherette.

Engineering and use context

The combination of higher impedance and high sensitivity is a practical engineering balance - the higher-than-usual impedance reduces the effect of a source's output impedance and background noise, while the high sensitivity still lets ordinary devices reach comfortable listening levels without a dedicated amplifier. The closed-back design isolates the listener from outside noise and keeps sound from leaking out, so the CL-20 can be used in shared spaces such as offices, libraries or a household at night without disturbing others. Pivoting earcups adjust to the angle of the head for an even seal, and the leatherette cushions reinforce that seal while spreading pressure for longer wear. A sister model, the CL-20i, uses the same housing and driver specification but adds an in-line microphone and remote for calls and playback control. Like most Koss headphones, it is backed by the company's long-standing limited lifetime warranty.

Pairing

The CL-20 plugs straight into computers, tablets, portable players and phones with a mini-jack output, and into hi-fi amplifiers and receivers with a standard 6.3mm adapter. With its higher impedance, it is also a better match than typical 32-ohm models for the headphone outputs of older hi-fi amplifiers, which often have a high output impedance. For phones without a headphone jack, a USB-C or Lightning DAC adapter completes the connection.

Alternatives

Koss' own CL/80 is a related model from the same clear-housing retro series for buyers who want the look with a different earcup design.