Наушники — Stax SR-007MK2

The SR-007MK2 is an over-ear electrostatic earspeaker from the Omega series of Stax, the Japanese company known for electrostatic headphones and their dedicated driver units. The model dates from 2007, used the 5-pin Pro bias standard and has since been discontinued, replaced by the SR-007S.

Key specs that matter

In each earcup Stax fits a push-pull electrostatic circular element, housed in an open-air enclosure. The quoted bandwidth is 6 Hz to 41,000 Hz. Capacitance is 94 pF with the cable counted, and impedance reaches 170 kohm measured at 10 kHz. Sensitivity is 100 dB at an input of 100 V RMS at 1 kHz, and the bias voltage is 580 V DC. Without its cable the headphone weighs 366 g.

Engineering and use context

Most electrostatic stators are perforated across their whole surface, but the fixed electrodes of the SR-007MK2 have gold plating on the outer edge and no perforations there. This layout enlarges the vibrating area of the diaphragm. Ear pads use lamb leather on the surfaces that touch the skin, with synthetic leather used for the surrounding portion of each pad. The cable is a low-capacity wide flat type made from PC-OCC (Pure Crystal Ohno Continuous Casting) copper and runs 2.5 m. Left and right are marked with L and R at the cable entry, and the cable itself carries a solid line on the left lead and a dotted line on the right. Stax lists an operating range of 0 to 35 degrees Celsius with a maximum of 90 percent humidity and no condensation.

Pairing

Being electrostatic, the SR-007MK2 cannot be driven by a normal amplifier and connects only to a Stax energiser fitted with a Pro bias socket. Current options include the solid-state SRM-400S and SRM-700S, the hybrid tube SRM-500T and SRM-700T, and the SRM-D50, which combines a driver with a DAC and provides 59 dB of gain. The larger SRM-T8000 uses E88CC dual triodes, takes line signals over two RCA pairs or one XLR pair, and reaches 470 V RMS. The SRM-400S is an all-stage FET DC amplification unit with RCA and XLR inputs, 60 dB of gain and a maximum output of 400 V RMS.

Alternatives

The Stax SR-007S is the current Omega model, with renewed diaphragms and fixed electrodes, sheepskin ear pads, a single-piece stainless steel ARS arc taken from the SR-X9000 and a detachable cable.