Can any body tell me what is the main difference between small satellite speakers and tower speakers???
The human ear can usually hear and discern sound frequencies from 20Hz from 20KHz.
The loudspeakers we generally use have something called drivers inside which are used to play these frequencies for our hearing. Since it is difficult for one driver to play all the frequencies, manufacturers have divided the frequencies into broad categories as follows:
low bass : 0 > 100hz
mid bass : 80 > 500hz
mid range: 400 > 2khz
upper mid: 1k > 6khz
high freq: 4k > 12khz
Very high freq: 10k > 20khz and above
You need drivers of different sizes to reproduce each of these categories of sound frequencies. For example, to reproduce a low frequency of 100Hz and below, you need a driver that is usually 8 inches or higher in diameter. Mids can be reproduced by drivers that have a size of around 5 to 6 inches. High and very high frequencies can be reproduced by small drivers that are 1 to 3 inches in diameter.
You can, of course, make individual speakers for each of these frequency ranges, but that would unwieldy and expensive. So, a floor stander usually has three drivers, each of which can handle a particular range. An amplifier sends all the frequencies to the speaker. An small electronics inside called a crossover subdivides these frequencies and sends them to the respective driver.
Floor standers are big and need large floor space. With the advent of the flat system people started using small rooms where it will be difficult to place these floor standers. In addition, it will look funny if you keep such large speakers next to a computer.
Companies such as Bose came up with the concept of a sub woofer / satellite system. In this the amplifier sends all the frequencies to an active sub woofer. Within the sub woofer, the signal is bifurcated into low frequencies (and some mid frequencies) that the sub handles by itself. The mid bass and high frequencies are, instead of being sent to a drivers inside the sub itself, sent to an independent speaker called a satellite or Sat. The Sats are usually very small and have one or more drivers between 1 to 3 inches. Since such speakers do not move much air, these units are completely sealed and are sometimes made with metal such as aluminium. Such speakers can only play frequencies in the range of 1000Hz (1KHz) to 20,000Hz (20KHz).
A satellite cannot be used without the sub woofer. It will sound very tinny of used in that fashion.
cheers