What can be used to reduce RF current flowing on the shield of an audio cable?

Using a ferrite choke is an effective method to reduce RF (Radio Frequency) current flowing on the shield of an audio cable. Ferrite chokes work by introducing inductive reactance to the currents that attempt to flow. RF currents, which are typically at higher frequencies, face increased impedance when they pass through the choke, thus reducing their amplitude. This is particularly valuable in audio applications where RF interference can introduce noise and degrade audio quality.

The presence of a ferrite choke on the audio cable shield helps ensure that any stray RF signals are suppressed, allowing the intended audio signal to pass through without interference. This makes it a commonly recommended component in audio setups, especially in environments where RF emissions could create problems, such as near radios or transmitting antennas.

Other choices like band-pass and low-pass filters serve distinct purposes related to frequency selection and signal processing but do not directly target the problem of RF currents on cable shields. A preamplifier amplifies weak audio signals but does not reduce RF interference. Thus, when dealing with RF currents on audio cable shields, the utilization of ferrite chokes is the most straightforward and effective solution.