Inductor: An inductor is an electronic device which consists of a coil of wire which may have a metallic or ferrite core. If it appears to have no core, it is considered to have an air core. The core material will greatly affect the value of the inductor. The unit of measure is the 'henry', but since that is such a large value of inductance, the value is usually stated in millihenries. One henry is equal to one thousand millihenries. If everything else stays constant, increasing the number of turns of wire around the core, will increase the value of the inductor. This is the schematic symbol for an inductor. This one example of what an inductor might look like. Inductor core types used for audio Iron Core: Laminated iron cores are generally used in low cost, low power inductors. Iron core inductors are good for low power crossovers. If they are used in high power systems (generally over 100 watts), the core may saturate. Ferrite Core: Ferrite core inductors are used in moderately high power systems. They can generally be used up to 250 watts (depending on the electrical properties of the ferrite material). A larger gauge wire must be used (compared to the iron core) to keep the DCR at acceptable levels. Air Core: Air core inductors are the high power champs. They will not saturate with high power. The wire must be even larger than the ferrite core because much more wire must be used in the coil to reach a given value.