Mundorf E-Cap audio and signal coupling capacitors are bipolar electrolytic capacitors. They are used in applications where film capacitors are not suitable for space or cost reasons, as they are generally much more compact than their film counterparts. In particular, they are widely used in crossover filters.

There are two ranges of E-Cap capacitors. The RAW range consists of the ECAP100 and ECAP63 models (BR100 and BR63). Capacitors in this range are made of foils whose surface is roughened by a special etching process that enlarges their surface. As the capacitance is proportional to the surface area, this process results in compact and inexpensive capacitors.

These capacitors are bipolar and have a second aluminium foil for resistance to AC voltage, making them suitable for AC audio signals.