ESS TEMPEST-LS-3: The Forgotten Hybrid Electrostatic Marvel

Name: ESS TEMPEST-LS-3
Brand: ESS

In the mid-1980s, the high-end audio world was in the throes of experimentation. Manufacturers were pushing the boundaries of loudspeaker design, seeking to overcome the limitations of conventional dynamic drivers. Among the most ambitious and technically daring companies of the era was Electro-Static Sound (ESS), a California-based firm known for its bold approach to transducer technology. While ESS is best remembered for its iconic Heil Air Motion Transformer (AMT) drivers and models like the CL-3, the TEMPEST-LS-3 stands as one of the company’s most enigmatic and underappreciated creations — a hybrid electrostatic loudspeaker that fused planar magnetic bass with a horn-coupled electrostatic panel for midrange and treble.

Though not as widely documented as other ESS models, the TEMPEST-LS-3 emerged during a golden age of speaker innovation, when companies like MartinLogan, Acoustat, and Sound Lab were exploring the potential of electrostatics. ESS took a different path, combining their proprietary driver technologies into a single, cohesive — and visually striking — floor-standing design.

Technical Specifications

Specification	Detail
Type	Hybrid electrostatic / planar magnetic
Driver Configuration	1 x ESS electrostatic panel (horn-coupled), 2 x 10" planar magnetic bass drivers
Frequency Response	35 Hz – 22 kHz (±3 dB)
Sensitivity	86 dB (2.83V/1m)
Nominal Impedance	4 ohms (varies with frequency)
Crossover Type	External passive crossover with active bass option
Recommended Amplifier	50–200 watts, high-current capable
Dimensions (H×W×D)	72" × 24" × 18" (183 cm × 61 cm × 46 cm)
Weight	110 lbs (50 kg) per speaker
Enclosure Material	Medium-density fiberboard (MDF) with real wood veneer
Finish Options	Rosewood, Black Ash, Cherry

The TEMPEST-LS-3 employed a vertical array design: a large, curved electrostatic panel was mounted centrally, flanked by two planar magnetic bass units housed in sealed cabinets. The electrostatic section used a horn-loaded stator design, a rare approach intended to increase efficiency and dispersion — a hallmark of ESS’s engineering philosophy. Unlike traditional electrostatics that rely on a large diaphragm suspended between perforated plates, the TEMPEST-LS-3’s panel was folded and coupled to a horn structure, improving midrange output and reducing the need for extremely high bias voltages.

The bass drivers were ESS’s own planar magnetic units, utilizing a lightweight conductive ribbon suspended in a magnetic field. These drivers offered fast transient response and low distortion, complementing the electrostatic panel’s clarity.

An external crossover network was standard, allowing for system tuning and, optionally, bi-amping. Some units were sold with an active bass module, enabling users to drive the low-frequency planar drivers with a dedicated amplifier — a forward-thinking feature for its time.

Sound Characteristics and Performance

The sonic signature of the TEMPEST-LS-3 was nothing short of revelatory for those who heard it. Listeners consistently reported a lifelike midrange, with vocals and acoustic instruments rendered with startling realism. The electrostatic panel delivered exceptional speed and transparency, free from the coloration often associated with dome tweeters or dynamic midranges.

Treble extension was airy and detailed without being harsh — a common pitfall of early electrostatics. The horn-loading of the panel contributed to a more even dispersion pattern, reducing the "sweet spot" limitations typical of flat-panel designs.

In the bass, the planar magnetic drivers offered tight, articulate low-end performance. While not quite matching the sheer output of large dynamic woofers, they excelled in pitch definition and speed, making the TEMPEST-LS-3 particularly well-suited to jazz, classical, and acoustic recordings. The transition between the electrostatic mid-treble and planar bass was generally seamless, thanks to careful crossover design and time alignment.

Overall, the TEMPEST-LS-3 presented a spacious soundstage, with precise imaging and excellent depth perception. It demanded high-quality source material and amplification, but when properly driven, it could rival far more expensive contemporaries in transparency and musical engagement.

Notable Features and Innovations

The TEMPEST-LS-3 was a showcase of ESS’s engineering ingenuity:

Horn-Coupled Electrostatic Panel: A rare design that improved efficiency and dispersion, reducing the need for ultra-high voltage power supplies.
Hybrid Planar Design: The fusion of electrostatic and planar magnetic technologies allowed ESS to sidestep the bass limitations of pure electrostatics without sacrificing clarity.
Modular Crossover System: The external crossover enabled bi-amping and fine-tuning, appealing to audiophiles who wanted to optimize system synergy.
Aesthetic Boldness: With its sweeping curves and exposed panel, the TEMPEST-LS-3 was as much a piece of industrial art as it was a loudspeaker.

Few speakers of the era attempted such a radical synthesis of technologies, and even fewer executed it with the coherence that ESS achieved here.

Common Issues and Maintenance

Like many vintage electrostatic and planar designs, the TEMPEST-LS-3 requires careful maintenance:

Panel Degradation: Over time, the electrostatic diaphragm can become brittle or develop weak spots, leading to arcing or reduced output. Humidity control is essential.
Bias Supply Failure: The high-voltage power supply that charges the stators may fail due to aging capacitors or transformer issues. Replacement parts are scarce but can sometimes be sourced from MartinLogan or DIY audio suppliers.
Planar Driver Wear: The conductive traces on the planar bass drivers can fatigue or break, especially if overdriven. Repairs are possible but require specialized skills.
Crossover Components: The external crossover uses aging capacitors and inductors that may need recapping or refurbishment.

Owners are advised to power the speakers gradually using a variac and to avoid extended periods of inactivity. Regular cleaning of the perforated stators with compressed air is also recommended.

Current Market Value and Collectibility

The TEMPEST-LS-3 is a rare find today. Fewer than 500 pairs are believed to have been produced, and many have been lost to time due to maintenance challenges. Surviving, fully functional pairs occasionally appear on audiophile forums, eBay, or specialty vintage audio marketplaces.

When available, prices typically range from $1,200 to $2,500 per pair, depending on condition, originality, and whether the crossover and power supplies are intact. Fully restored units with upgraded electronics can command higher prices, especially among collectors of hybrid and experimental speaker designs.

While not as mainstream as MartinLogan or Acoustat models, the TEMPEST-LS-3 holds a cult following among ESS enthusiasts and those who appreciate bold, unconventional engineering. Its rarity and technical ambition make it a compelling piece for the discerning vintage audio collector.

Conclusion and Legacy

The ESS TEMPEST-LS-3 may not have achieved the commercial success of other ESS models, but it remains a testament to the company’s fearless pursuit of sonic excellence. It represents a fascinating "what if" in loudspeaker history — a hybrid design that attempted to marry the best qualities of electrostatic clarity with planar bass control.

Though ESS faded from prominence by the early 1990s, the TEMPEST-LS-3 endures as a symbol of an era when audio engineering was as much art as science. For those willing to invest the time and care, it offers a listening experience that is still relevant — and deeply rewarding — decades later.

In the world of vintage audio, the TEMPEST-LS-3 isn’t just a speaker. It’s a statement.