How to make a qualitative subwoofer in the car?
Before starting purchase of the low-frequency loudspeaker (in other words: sabvuferny head; LF - a head), to production and installation of all subwoofer in the car, you have to imagine accurately how your speaker system will look (let`s agree: the speaker system we will call that box for a sabvuferny head which we, finally, and should make).
“ Acoustic registration, or a box which you chose for a subwoofer will be the defining factor in achievement of high-quality sounding in low-frequency area of a bass “. the Theory
But for a start is a little
about mission and function of any box. The acoustic head radiates a sound not only “ forward “ but also back, at the same time frontal and rear sound waves are opposite on a phase. Such waves extinguish each other, respectively, sound pressure low and as a result - low loudness! Acoustic LF registrations - heads it is intended for liquidation of such acoustic short circuit.
Distinguish of 4 main types of acoustic registration:
• the closed type (ZK);
• the case with the phase inverter (FC);
• strip type (personal computer);
• infinite acoustic screen (free air).
Sound pressure of a sabvuferny head in ZK is less than pressure, rendered by the same loudspeaker placed in FC on 3 DTs and on 6, than in the personal computer. Increase in sound pressure on 3 DTs leads to increase in loudness of sounding twice, therefore, increase on 6 DTs - in 4! Thus, use of more difficult speaker system allows to apply less powerful amplifiers with an equal loudness of sounding! Ieto it is very important, the price on amplifiers grows in proportion to their power.
Now is more detailed about each type of the speaker system.
Closed Case (CC)
the simplest type of the speaker system! In this case the low-frequency loudspeaker is mounted in some box by the face outside. In such box the difference of phases of fluctuations of a sound from front and the back of the loudspeaker is liquidated very simply. The sound from the back of a loudspeaker is extinguished in the closed box volume. This sound wave cannot eclipse a sound from frontal part of the loudspeaker any more.
Certainly, such speaker system is simple in production, but there are also several essential minuses . In - the first, low, so to speak, efficiency, useful “ work “ only the frontal part of the loudspeaker makes. In this regard more powerful amplifier is necessary that, of course, will affect finansova expenses.
In - the second, there is a probability that the loudspeaker will burn down! The closed volume of a box extinguishes the sound wave possessing energy therefore internal energy of all system increases and, it heats up. It is necessary to sheathe internal walls of such box the soundproofing materials, the sound is extinguished - heat is absorbed.
The case with the phase inverter (FC)
More difficult system of acoustics. Structurally a little in what differs from the closed case, with only that difference that has openings with hollow tubes of a certain length - ports of the phase inverter. The sound technical difference is huge. The phase inverter represents a hollow cylindrical tube of a certain diameter and certain length. By means of the phase inverter the closed volume connects to surrounding space.
How the phase inverter works? The tunnel of the phase inverter detains the sound wave formed in a subwoofer for strictly certain time. Thanks to it sound waves from “ front “ the parties of the loudspeaker and back meet beyond limits Saba in one phase. Sound pressure sharply increases! Minus is constructive complication of system, and also high sensitivity to parameters of the loudspeaker and geometrical parameters of a box and the phase inverter.
Case of strip type (personal computer); (Band - Pass) by
At such approach reaches the maximum sound pressure. LF - a head is entirely in a box and therefore it is protected from mechanical damages. Whimsical piece in calculation and the most labor-consuming in production. As the loudspeaker is in the case, it is necessary to go on tricks on assembly of a box so that existence of the removable panel did not break rigidity and tightness of a design. The box design allowing to operate the amplitude characteristic as in the field of the lower, and top frequency thanks to the case with a double chamber.
Infinite acoustic screen (free air)
the simplest acoustic registration: a box is any room or limited space! In the car the luggage carrier (well, of course, if a car class - a sedan) can be that.
Directly a car - acoustics
as a car body can be divided into three classes:
1. The salon is combined with a body (a hatchback, the versatile person).
2. The salon is isolated from a luggage carrier (sedan).
3. Open body (cabriolet).
Each class of cars has the features of installation of acoustics, and not any acoustics can be installed in this or that machine! Silly and madly to try to put a type subwoofer the Infinite Acoustic Screen in the class car a hatchback.