There's a discussion on AA regarding the use of Cardas Caps and similar devices to cover the openings of unused input and output RCA jacks of electronic equipment to deal with the problemm of RF entering the component via the open jacks. One person, the OP, reported a noticeable improvement by placing paper tape over all unused input and output jacks on his components. He then tried attaching small amethyst crystals over the open jacks instead of paper tape and reported much better results.

The question here is rather simple. Can RF really enter the component via the RCA jacks or is the wavelength of RF too long to fit through the small diameter of the jacks? Furthermore, since paper is transparent to RF, how can his "noticeable results" with the paper tape be explained? I.e., is there something else going on here, something more mysterious than RFI, something about simply blocking the openings? Finally, are the amethyst crystals actually absorbing RF or are they perhaps acting as dampers, or simply blocking the opening like the paper tape? If the openings of the jacks are too small to allow RF to enter then even if crystals have the property of RF absorption, their use as RF absorbers would be rather moot in this case given that the RF wavelengths are longer than the RCA jack diameter.

Has anyone tried Cardas Caps or similar on unused RCA inputs and outputs?

Geoff Kait

Machina Dynamica

Advanced Audio Concepts