Try to decide what type of acoustics you prefer: component or coaxial? Coaxial speaker consists of all frequencies collected in one place. A good reproduction of the sound will not differ. In a component speaker system all speakers are separate. Of course, such sets of columns are much more expensive, but with their sound you will get the effect of "presence", and even the untrained ear will easily be able to recognize any instruments.
Select the number of speakers for the car. They range from single-lane to chetyrehpolozyj. At the core of each sound range lies a separate speaker. The most simple sound systems are those that consist of one or more small speakers and is rigidly fixed in front of the diffuser, just forming a coaxial acoustic system. They are inexpensive and easy to install in the car.
Determine the required input sensitivity: from its height depends on the sound quality without an amplifier. The lowest sensitivity threshold is 84-86 DB. The sound in this case is very weak and will necessarily require additional signal gain. Select indicators within 92.
Think about the optimal resonant purity: the lower it is, the deeper the bass will be able to give dynamics. See to it that the Fs measure was the amount of 60-75 is optimal for good bass depth.
Select the frequency range. Every system has its frequency limits, about +/-3 dB. For the overall quality of the sound meets the Qts parameter. If in the manual it will be marked in the area of 0.4-0.6, it is very small: the figure should be 2 times higher, especially for those speakers that will be installed in each door.