In some cases, the same device Best Powered Speakers and amplifier. These devices are easily recognized for requiring power, unlike speakers without amplifier, which do not normally require it.
A sound system can have as many speakers as desired, as long as they are properly arranged and connected to the rest of the equipment (to the amplifier) correctly, always maintaining their polarities.
As with amplifiers, the speakers also have similar technical specifications that must be taken into account to ensure optimum performance.
There are several types of speakers that, according to their own characteristics, fulfill different functions.
They are the most common loudspeakers (and also, in general, of lower quality than the separated track loudspeakers). They can consist of 2 or more tracks through which the sound is emitted, but always starting from the same axis.
They are especially suited to equip sound systems with low budget, or intended to cover large spaces in which it would be difficult to implement with optimal results loudspeakers of separate tracks. This is the case with external sound systems, for example, or musical strings.