Circuit diagrams, or schematics, have two primary elements: symbols that represent components in the circuit and the lines that indicate the connections between these components. The symbols are generally accompanied by labels indicating their specifications and functions. Schematics also show the connection points for each component, and these correlate with the physical terminals of the actual part.
A speaker system consists of an amplifier, connections and at least one speaker. Speakers, which constitute the load in such configurations, resist the flow of electrical current. This behavior is referred to as impedance, and it is measured in ohms. The power that an amplifier has to provide in order to drive speakers has an inverse relationship with impedance; the lower the impedance, the greater the power that an amplifier has to supply.
Speakers have an impedance of 4, 8 or 16 ohms. When two or more speakers are wired in series, resistance to electrical flow increases by a factor that is computed by aggregating the impedance of speakers in the system. For instance, resistance doubles if the system has two speakers and quadruples when the number of speakers rises to four. In contrast, wiring speakers in parallel reduces impedance by a quarter.
An alternate wiring method known as series-parallel involves connecting, in parallel, groups of speakers wired in series. This arrangement results in impedance equivalent to that of a single speaker in the system.