*Question T7B04:
Which of the following could you use to cure distorted audio caused by RF current on the shield of a microphone cable?*  

*Correct Answer is  D: Ferrite choke*  

### AI Response: (may contain errors)  

To address the issue of distorted audio caused by RF current on the shield of a microphone cable, the correct answer is a ferrite choke.

### Explanation of the Correct Answer:
- **Ferrite Choke**: A ferrite choke is used to suppress high-frequency noise, including RF interference. It works by providing a high impedance to the RF signals while allowing the audio signals to pass through. This helps to prevent RF currents from affecting the audio quality.

### Why the Other Choices are Incorrect:
- **A: Band-pass filter**: 
  - A band-pass filter allows signals within a certain frequency range to pass while attenuating frequencies outside that range. It is not effective for eliminating RF noise, which may fall outside the desired audio frequency range.

- **B: Low-pass filter**: 
  - A low-pass filter allows low-frequency signals to pass while attenuating high-frequency signals. While it can reduce some RF noise, it may also cut off higher audio frequencies, leading to a loss of audio quality.

- **C: Preamplifier**: 
  - A preamplifier amplifies weak audio signals to a usable level. It does not address RF interference; in fact, it may amplify the RF noise along with the audio signal, worsening the distortion.

### Summary:
- Use a **ferrite choke** to effectively suppress RF interference on microphone cables.
- Avoid using band-pass or low-pass filters for this purpose, as they do not specifically target RF noise without affecting audio quality.
- A preamplifier is not suitable for noise suppression and may exacerbate the problem.