The HD 800 S is a circumaural headphone with open earcups made by Sennheiser, built around a dynamic transducer of the ring radiator type. Unlike a conventional dynamic driver, the central part of the diaphragm does not move, since it is held by a fixed piece, and only the annular section around it is driven. Its Sennheiser article number is 506911, and the pads enclose each ear fully.
Key specs that matter
The transducer is 56 mm in size, with a 40 mm voice coil that Sennheiser winds in-house to keep its shape and consistency. The magnetic field strength is quoted at 10.5 mT. Sennheiser specifies frequency response as 4 Hz to 51,000 Hz, nominal impedance as 300 ohm and sound pressure level as 102 dB at 1 V. Total harmonic distortion is below 0.02 percent at 1 kHz and 1 Vrms. The headphone weighs 330 g without cable, and it comes with two 3 m cables, one with a 3-pin 6.35 mm plug for unbalanced outputs and one with a 5-pin 4.4 mm balanced plug.
Engineering and use context
Sennheiser describes the HD 800 S as a result of several combined measures rather than a single feature. The chassis is designed to dampen vibration, the headband has inert damping, and a patented absorber system in the earcup targets a narrow frequency band. Each driver sits at a precise angle inside the cup, so that their output reaches the ear at what the maker calls its natural inflection point, rather than straight into the ear canal. All contact points use soft microfiber padding, which matters in long sessions given the size of the earcups. Because the back is open, the headphone lets outside noise in and leaks its own output into the room, so it is aimed at quiet home and studio listening and is less suited to commuting or open plan workplaces.
Pairing
The high impedance combined with a rating given per volt means the HD 800 S needs a dedicated headphone amplifier able to supply adequate voltage rather than a phone or laptop output. Owners of a balanced amplifier with a Pentaconn socket can use the supplied balanced cable directly, while single-ended desktop amplifiers and integrated amplifiers with a standard jack connect through the other cable.
Alternatives
The Sennheiser HD 660S2 sits below it as a lower priced headphone with open earcups in the same audiophile range.