Stax ‘Earspeaker’ Celebrates 80 Years

Iconic electrostatic maker Stax is celebrating its 80 year anniversary producing some of the very best personal audio products with the release of the new SR-L300 Limited ‘Earspeakers’. A companion SRM-353X BK ‘Driver’ (headphone amplifier in Stax-speak) has also been announced.

The new SL-R300 Limited Earspeaker (only 800 units produced) features many of the technologies adopted in Stax’s much-hailed SL-R700, such as the proprietary ‘MLER’ electrode structure utilising combined heat diffusion metal plates created to minimise resonance throughout the structure. The solid electrodes are machined via “stainless photo etching” techniques that have resulted in improved sonic performance.

Distributor Audio Marketing’s Tim Sleath told SoundStage! Australia, “the Earspeaker’s construction techniques result in a precise balance of a deep, rich bass response, delicate high-frequency and soothing mid-range.”

The SL-R300 Limited features a high purity OFC copper cable with multi-strand construction in a precise “wide parallel structure” winding methodology in order to lower the cable’s capacitance.

The SL-R300 Limited is a Push-Pull electrostatic open-air design with oval sound elements. The specifications feature an impedance of 145 kohms, a frequency response from 7Hz to 41kHz and a sensitivity of 101dB for an input of 100 VRMS at 1kHz.


The SRM-353X BK ‘Driver’ headphone amplifier, in its non-magnetic aluminium alloy luxury chassis, is the perfect companion for the SL-R300 Limited. A headphone amplifier capable of driving electrostatic Earspeakers needs careful design and particular engineering techniques. As Tim Sleath explained, “The SRM-353X BK is made from carefully selected high-quality parts resulting in a wide frequency response, natural tonal quality, and extended dynamic range at high frequencies.”

The circuit design of the SRM-353X BK is based on a directly-coupled Class-A DC amplifier configuration devoid of coupling-capacitors while the first stage features a low-noise dual FET. A “brushed-up emitter-follower” has been incorporated in the output stage and is claimed to expand dynamic range at the frequency extremes while also providing all-round sonic improvements. Volume control is a via a custom-made twin-axis four-gang high quality pot.


The headphone amplifier’s frequency response is quoted at DC to 90kHz when used with an SL-R series Earspeaker. Gain is 60dB while the input impedance is 50 kohms via the RCA and XLR inputs (one input of each).

The Stax SL-R300 Limited Earspeakers and SRM-353X BK Driver headphone amplifier are available in Australia via Audio Marketing’s established dealer network.

Australian Distributor: Audio Marketing
+ 61 2 9882 3877

Price: SL-R300 Limited AU$999, SRM-353X BK AU$1699