Наушники — Stax SR-X9000

The SR-X9000 is an electrostatic earspeaker from Stax, introduced in 2021 as the successor to the SR-009S. Its fixed electrode revives the metal mesh concept that Stax used in the SR-X of 1970 and the SR-Omega era. The Japanese list price is JPY 693,000 with tax included, and in the US the price is USD 6,200. It is made in Japan.

Key specs that matter

Stax builds it as a push-pull electrostatic unit with a large circular element in a rear-open enclosure. Frequency response covers 5 to 42,000 Hz. Capacitance is 110 pF including the cable, and impedance is 145 kohm at 10 kHz. Sensitivity is 100 dB for an input of 100 V rms at 1 kHz, and the bias voltage is 580 V DC. The headphone weighs 432 g without the cable. The package includes a pair of detachable, reconfigurable cables, 2.5 m and 1.5 m in length, built from a 6N OFC core of 99.9999% purity combined with silver-plated annealed copper wire, with the copper carrying the low frequencies and the silver-plated wire the high ones.

Engineering and use context

The MLER-3 electrode has four layers - a mesh electrode and a conventional etched electrode joined by thermal diffusion bonding, a technique Stax developed over some 20 years of research. The result is a rigid structure that resists resonance. The diaphragm is an ultra-thin film of engineering plastic with 20% more area than the one in the SR-009S, and its mass has been reduced for fast transient response. A CNC-machined aluminium housing holds the sound unit firmly to suppress unwanted vibration, and a tilted guard mesh controls acoustic reflections. The arc assembly of the headband is stainless steel with an I-shaped aluminium stabiliser and a nine-position click adjuster. Earpads are sheepskin leather for breathability, and a paulownia wood storage case with low thermal conductivity is supplied.

Pairing

The SR-X9000 plugs into a Stax driver unit with a Pro-bias socket and cannot run from an ordinary headphone amplifier. The two supplied cable lengths suit either a driver on the desk or one placed further away on a rack. Suitable Stax drivers range from the SRM-500T tube hybrid to the SRM-700S, which reaches 450 V rms, and the SRM-T8000, rated at 470 V rms.

Alternatives

The SR-009S remains in the Stax range with the gold-plated MLER-2 electrode, a die-cast aluminium chassis and a weight of 441 g without cable.