Test & measurement
A film/foil capacitor is a non-polarized capacitor. Its dielectric is made using a thin plastic film between two layers of electrodes made out of aluminium foil. In other terms, a film/foil capacitor identical to a bipolar capacito Show more
A film/foil capacitor is a non-polarized capacitor. Its dielectric is made using a thin plastic film between two layers of electrodes made out of aluminium foil. In other terms, a film/foil capacitor identical to a bipolar capacitor, just with a thin plastic film/foil as their dielectric. It can either be inductive or non-inductive. The film/foil capacitor is known and valued for its low distortion factor and its excellent frequency characteristics. Also, it comes with a high insulation resistance and good capacitance stability. However, the main advantage of film/foil capacitors is that their internal construction is their direct contact to the electrodes on both of the winding's ends, which keeps all currents paths short.
Capacitors are almost essential in most electrical circuits, and their quantity varies from application to application. A capacitor is an electrical component in which an electrical charge can be stored on one side (+), with the opposite charge's simultaneous storage (-). In audio applications, they are mainly used in crossover filters, where the combination with other components determines the filter's behaviour.
However, if you want to learn more about capacitors, please check out our detailed blog, "The basics of crossover components"! The blog also explains what you have to look for when choosing a capacitor!
The film capacitor serves the same function as all other capacitors. They accommodate the electric charge. However, film capacitors are superior to other general capacitors in terms of efficiency due to their superior characteristics. Film and foil capacitors are known for high insulation resistance, low dielectric loss, no polarity and excellent frequency characteristics (wide frequency response).
This question can not be answered with a specific number. There are capacitors installed in crossover boards that work for over 40 years, but there are also modern crossover boards where the capacitor fails after a couple of years. The lifetime gets influences by several factors, such as material quality, heat exposure, moisture exposure and intensity of use. However, in general, it can be said that a capacitor has an expected life expectancy of 10 – 15 years.
The main difference between a capacitor and a battery is that a capacitor can be charged and discharged in a fraction of a battery's time. However, the price a capacitor has to pay for this advantage is its energy density – a battery can store a more significant amount of energy in the same space/size than a capacitor. In other words, if a battery and a capacitor would have the same size, a capacitor could only store a fraction of the energy a battery could store.
The main difference can be traced back to the type of dielectric used and its construction. The film/foil capacitors here at SoundImports are available in a wide range of capacitance values. Also, film/foil capacitors are more likely to resist ageing over time, making them the favoured choice for high-frequency applications such as speaker building.