Customising capacitors in the UK

Charcroft’s Debbie Rowland explains how UK design and manufacture of custom capacitors and assemblies simplifies procurement for audio, rail and industrial

Customisation is a valuable engineering option to meet high component specifications or to fit a new/legacy footprint. For buyers, customisation carried out in the UK can make sourcing faster and simplify procurement paperwork.

One of the problems with sourcing custom capacitors for audio, rail and niche industrial sectors is the comparatively low volumes. While some global component manufacturers produce capacitors for these sectors few, if any, have the bandwidth to manufacture custom capacitors or assemblies in such low volumes.

There are smaller component manufacturers which focus almost exclusively on high-end audio but high-level customisation is not a standard service.

Development of a custom capacitor is driven by the customer. One reason a custom capacitor or assembly is essential is to ensure the component delivers the right parameters in the available footprint. It could be a higher capacitance, voltage or current rating with an optimized equivalent series resistance (ESR).

The answer may be found in the special design of a single capacitor or by combining multiple capacitors in a single case with custom packaging to fit a space envelope.

Designing a capacitor presents multiple options, starting with the choice of dielectric film, metallisation material and pattern, plus key dimensional characteristics directly impacting the capacitor’s performance. Multiple termination options exist and further testing and conditioning can affect the part’s stability. Capacitors can be matched together where stability is critical, such as railway signalling applications.


For audio applications, minimising unwanted resonance is key. The factors which impact resonance have been identified and measured through years of research and development, resulting in treatments applied during winding manufacturing. Using multiple, series-wound windings can also reduce resonance by shortening the active area, while packaging inside a custom acrylic tube further dampens resonance.

As recent acquisitions by Charcroft, the focus for ClarityCap and ICW Film Capacitors is audio and rail/niche industrial respectively. All these capacitors are designed and manufactured in Wrexham, UK, enabling interaction in the same time zone/language, plus fast turnaround.

A shipment of customised passives from Europe can take up to a week. Instead, ClarityCap and ICW ship directly from the Wrexham plant using parts from Charcroft UK-held franchised distribution stock. This can enable a one-day turn-round and means an urgent custom part can be provided to the customer in 24-hours.

Iterations are fast too. In a recent customisation, six iterations were completed in three weeks, including initial specification to drawing, prototyping for customer approval and starting production.

For audio manufacturers, a capacitor’s sound is only the start of the wish-list: look is often just as important. There is a breakthrough audio capacitor being designed and manufactured by ClarityCap in the UK. For the capacitor’s looks to match its sound quality, it will be housed in a British Racing-Green case with a gold-glitter fill at each end. Capacitor branding includes adding the customer’s logo and corporate colours, plus the customer’s choice of leads and well-known audio interconnect brands.