About Reliable Capacitors

From the Wonder Cap era to AudioCapX

Long before the audiophile capacitor became a category of its own, designers were beginning to question whether capacitors could really be treated as interchangeable circuit components. By the late 1970s and early 1980s, specialist designs such as the original Wonder Caps had become part of a growing interest in the influence of dielectric materials, construction, losses and parasitic behaviour on the performance of audio circuits.

Richard Marsh was among those investigating these questions in considerable depth. His work examined the behaviour of real capacitors beyond the value printed on the case – including dielectric absorption, equivalent series resistance, inductance and high-frequency behaviour. It ultimately led to the MultiCap™, an approach in which several capacitor sections are wound within a single component and internally connected.

Turning that concept into a practical production capacitor required more than the idea alone. Bas Lim, then owner of Reliable Capacitors, developed the specialised winding machine used to manufacture the MultiCap and shared the MultiCap patent with Richard Marsh. The resulting construction was designed to address the parasitic resistance and inductance found in conventional single-section windings.

In 2019, MultiCap was renamed AudioCapX. The name changed; the multi-section construction did not.

Built differently

AudioCapX is therefore defined as much by the way it is made as by the materials used in it. Several capacitor sections are wound coaxially within a single component and internally connected, creating what Reliable historically described as an internally bypassed or self-bypassing capacitor.

Producing these capacitors requires specialised winding equipment. Today, Reliable’s capacitors are wound in-house on machines custom-built for the company. After winding, the capacitors are hand-finished at Wilson Audio’s facility in Provo, Utah.

There is something refreshingly old-fashioned about that approach. Not old-fashioned in technology, but in attitude: understand what the component is supposed to do, develop the construction around that purpose, and retain control over how it is made.

A long connection with Wilson Audio

Reliable’s relationship with high-end audio extends well beyond the specialist component market. Wilson Audio had used capacitors manufactured by Reliable for decades, particularly in the crossover networks of its loudspeakers.

In 2018, Wilson Audio acquired Reliable Capacitors and brought capacitor manufacturing in-house in Provo, Utah. This allowed capacitor development, prototyping and production to take place alongside the loudspeakers in which many of these components are used.

Reliable continues to produce its established ranges while also developing new materials, constructions and specialised capacitor configurations within Wilson Audio.

Still purpose-built

Almost five decades separate the early investigations into capacitor behaviour from today’s AudioCap and AudioCapX ranges, yet the underlying idea has changed surprisingly little.

A capacitor is simple only in the idealised circuit diagram. In a real circuit, dielectric behaviour, resistance, inductance, construction and manufacturing all become part of the component’s performance. Reliable’s different product families approach those factors in different ways – from traditional film-and-foil designs to PTFE and copper-foil constructions and the proprietary multi-section architecture of AudioCapX.

That continuity is perhaps the most interesting part of the Reliable story. The materials have evolved, the product range has grown and the company itself has become part of Wilson Audio, but the underlying idea remains recognisable: a capacitor may be a small part of an audio system, but its construction and behaviour still deserve attention.