Premier Guitar is running a series of columns on “unconventional” effects. Their current subject is that most unique device, the ring modulator. PG describes one well known example of the effect in action:
During the solo of Black Sabbath’s heavy metal super-hit “Paranoid,” guitarist Tony Iommi makes use of a ring modulator to add a fuzzy, stuttering element to his already fuzzy tone.
The column also outlines how to use the effect and provides reviews of the Electro-Harmonix Ring Thing and Dwarfcraft Hax, among others.
Read more and hear examples at PG.