Aluminum electrolytic capacitors are used in applications for which film capacitors are not suitable for reasons of space and / or cost. Polarized electrolytic capacitors which have the most compact design and therefore are used for very high capacities (for example for voltage supply of amplifiers) cannot transfer any audio signals because the audio signals are AC signals .
ECap AC · Audio Coupling & Signal Cap RAW series bipolar electrolytic capacitors have foils with roughened surfaces by a special etching process that enlarges the surface. Since the capacitance of the capacitors is proportional to their surface area, this process provides the smallest and cheapest Mundorf audio capacitors.
Bipolar electrolytic capacitors, such as those in the ECap AC series, have a second foil of aluminum that provides resistance to AC voltage and therefore makes them suitable for musical signals.