Наушники — Sennheiser HD 650

The HD 650 is an open-back, circumaural dynamic headphone from Sennheiser that has been in production since the mid-2000s, when it sold for roughly EUR 449. It belongs to the same family of open designs as the HD 600, HD 595, HD 555 and HD 515, and it is still offered at USD 579.95 with a two-year warranty. Production takes place in Ireland under tight tolerances of plus or minus 1 dB, so left and right transducers and individual pairs match closely.

Key specs that matter

Sennheiser describes the driver as an exclusive 42 mm transducer carrying a 38 mm diaphragm. Sennheiser now quotes a frequency response of 12 Hz to 41,000 Hz, while the original sheet quoted 10 Hz to 39,500 Hz at -3 dB. Nominal impedance is 300 ohms, the sound pressure level is 103 dB at 1 V, and total harmonic distortion stays under 0.05% at 1 kHz and 1 V. The headphone weighs 260 g without its cable, and contact pressure is about 2.5 N. The magnetic field strength is listed at 1.8 mT.

Engineering and use context

Behind the diaphragm Sennheiser fits a special damping element made from fine acoustic metal mesh, which controls the movement of air through the open back of the cup. The detachable cable is 3 m long and made from highly conductive OFC copper chosen for low handling noise and low sensitivity to structure-borne noise, so knocks against the lead are not passed into the earcups. It ends in a gold-plated 6.35 mm stereo jack plug, and a 6.35 mm to 3.5 mm adapter comes in the box. Because the cable detaches at the cups, it can be replaced after damage, or swapped for a shorter or balanced lead from another supplier without opening the headphone. The circumaural pads enclose the ear completely rather than resting on it, and the moderate clamping force keeps longer sessions comfortable. As an open design it leaks noise in both directions and is intended for home use.

Pairing

The combination of high impedance and moderate sensitivity means the HD 650 needs more voltage swing than most phones and laptop outputs can deliver, so a dedicated headphone amplifier or a DAC with a capable headphone stage is the usual partner. Amplifiers designed for high-impedance loads, including valve headphone amplifiers with output transformers or direct-coupled output stages, suit it well, and the long cable reaches a rack or desk comfortably.

Alternatives

The Sennheiser HD 660 S2 is a later open-back model with a newer transducer, an aluminium voice coil, higher sensitivity and both 6.3 mm and 4.4 mm cables in the box.