Mission 780 Argonaut: The Pinnacle of British High-End Speaker Design in the 1980s

Introduction

The Mission 780 Argonaut was introduced in 1985 and produced until 1990. It sat at the top of Mission's speaker lineup in the mid-to-late 1980s. British speaker design was busy at the time, with companies like Linn, Bowers & Wilkins, and Quad all pushing it along, and Mission made its name on innovation. The 780 Argonaut was its flagship. It combined a ribbon tweeter, push-pull bass drivers, and a carefully damped cabinet, and it offered transparency, dynamics, and bass control that were rare in its time. It was aimed at the audiophile who wanted both technical sophistication and musical realism.

Technical Specifications

Specification	Value
Model	780 Argonaut
Category	Floorstanding Speaker
Years Produced	1985-1990
Power Output	Recommended amplifier power: 25-200W
Impedance	8 ohms nominal
Frequency Response	35Hz - 20kHz
Total Harmonic Distortion	< 1% at 90dB
Signal-to-Noise Ratio	Not specified by manufacturer
Dimensions	1000mm (H) x 250mm (W) x 350mm (D)
Weight	28kg per speaker

Design & Engineering

The Mission 780 Argonaut was a three-way, floorstanding loudspeaker. Its most distinctive feature was the Argostat ribbon tweeter - a vertically aligned, electrostatic-inspired driver developed with the British company Apogee, known for its planar magnetic speakers. Unlike a conventional dome tweeter, the Argostat had very low mass and near-instantaneous transient response, which gave detailed, airy high frequencies. It sat above a 150mm midrange driver, and the pair gave a wide, coherent soundstage with precise imaging.

For bass, Mission used a push-pull configuration with two 200mm (8-inch) bass drivers mounted on opposing sides of the cabinet. The drivers cancel each other's vibrations, which cut cabinet resonance and distortion. It's a technique borrowed from high-end studio monitors and still used in premium speakers today. A bass reflex port extends low-frequency response down to 35Hz, and the bass stays deep and controlled, without the bloat or overhang common in many floorstanders of the era.

The cabinet itself was a study in acoustic engineering. Constructed from high-density fiberboard (HDF) with extensive internal bracing and mass-loading, the enclosure was designed to be acoustically inert. The tall, narrow profile minimized front baffle width to reduce diffraction effects, while the angular front panel contributed to a more focused stereo image. Available in high-quality real wood veneers—typically walnut or rosewood—the 780 Argonaut was as visually striking as it was sonically accomplished.

The crossover used high-quality components, including air-core inductors and polypropylene capacitors. The crossover points were set at approximately 500Hz (between bass and midrange) and 3.5kHz (between midrange and tweeter). The 780 Argonaut also supported bi-wiring, with separate terminals for the bass and mid/high-frequency sections, so owners could try high-end cabling on each.

Sound Characteristics

The sonic signature of the Mission 780 Argonaut was one of clarity, neutrality, and dynamic authority. Thanks to the ribbon tweeter, high frequencies were exceptionally clean and extended, with a natural decay that avoided the harshness sometimes associated with metal domes. Cymbals, strings, and vocal sibilance were rendered with lifelike precision, making the speaker ideal for classical, jazz, and acoustic recordings.

The midrange was transparent and well-balanced, with the 150mm driver delivering rich, articulate vocals and instrumental textures. The push-pull bass system provided tight, fast, and deep low-end response—capable of handling orchestral crescendos and electronic music with equal confidence. While not as thunderous as some larger transmission-line designs, the 780 Argonaut’s bass was remarkably controlled and articulate, with excellent pitch definition.

Overall, the speaker excelled in creating a wide, three-dimensional soundstage with precise imaging. Instruments were placed with surgical accuracy, and the ribbon tweeter’s wide dispersion contributed to a generous sweet spot. When paired with high-quality amplification—particularly valve or high-feedback solid-state designs from brands like Naim, Arcam, or Linn—the 780 Argonaut revealed its full potential as a reference-class loudspeaker.

Market & Collectibility

Today the Mission 780 Argonaut is a sought-after collector's item among vintage audio enthusiasts. It was never as common as some of its contemporaries, and it has a cult following for its mix of advanced technology and British design. On the secondhand market, working pairs in good cosmetic condition typically fetch between $800 and $1,500, depending on finish, originality, and the condition of the ribbon tweeters. The tweeters are the most fragile component and often need refurbishment.

Restoration projects are not uncommon. Specialists offer reconing for the bass and midrange drivers, as well as ribbon tweeter repairs. Original parts are scarce, so many owners fit modern equivalents that keep the speaker's character while improving reliability. Upgrading internal wiring and external speaker cables can also improve performance, though purists often prefer to keep everything original.

When buying a used pair, inspect the cabinet for veneer damage, check cabinet integrity (no rattles or loose panels), and verify that the ribbon tweeters are intact and working. A hissing or crackling sound at high frequencies usually indicates ribbon damage.

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