Different crystals have different frequency bandwidths of operation. No crystal is wideband so various types of crystals in combination can often produce better results than any single crystal. Experimentation is recommended but certain locations seem like a slam dunk, like on top of CD PLAYER over the spinning disc, on top of output transformer, on top of Tube Traps, in proximity to small vacuum tubes. In certain locations the resonance of the stones can hurt the sound, so don’t assume more or bigger is better or that they can be used anywhere. One of my products employs teeny tiny stones of various types including but not limited to sapphire, carnelian and obsidian and is highly effective when used as directed.
