ES Lab EX-1a Open-Back Electrostatic Headphone

The ES Lab EX-1a is an open-back electrostatic headphone from Hong Kong's ES Lab, a boutique shop that spent decades repairing and restoring rare Stax and vintage electrostats before building its own designs. If you've wanted true electrostatic speed and resolution without flagship pricing, the EX-1a is the most direct way in.

Type and Technology

A full-size electrostatic transducer with an ultra-thin 68 mm diaphragm runs on a DC 580 V bias and terminates in a 5-pin Stax-type Pro Bias plug. Like all true electrostats, the EX-1a requires a dedicated energizer or electrostatic amplifier — it will not work from a standard headphone amp or portable gear.

Sound Character

Expect what electrostats do best: vanishingly low distortion, fast transients, and natural tonality. The open-back design gives the EX-1a a spacious, airy presentation with precise imaging and real depth, and frequency response reaches from 10 Hz up to 41 kHz.

Build and Comfort

The housings are machined from aluminum-magnesium alloy for rigidity without bulk, and at roughly 380 g without the cable the EX-1a is light for a high-end electrostatic. The attached 2.3 m cable gives plenty of reach from a desktop energizer.

Best For

Listeners with a dedicated setup and a Stax Pro Bias-compatible amplifier who value soundstage, driver speed, and low-level detail — and who want boutique electrostatic craftsmanship at a price well under the usual flagships.

What's in the Box

• ES Lab EX-1a headphone with attached 2.3 m cable
• Warranty & product documentation

Specifications