subwoofer capacitor
Content
The operation of powerful car subwoofers may be accompanied by problems associated with the high current consumption of these devices. You can notice this at the peaks of the bass, when the subwoofer "chokes".
This is due to voltage drops at the power input of the subwoofer. The energy storage device, the role of which is played by the capacitance of the capacitor included in the subwoofer power circuit, helps to fix the problem.
Why do you need a capacitor for a subwoofer
An electric capacitor is a two-pole device capable of accumulating, storing and releasing an electric charge. Structurally, it consists of two plates (plates) separated by a dielectric. The most important characteristic of a capacitor is its capacitance, which reflects the amount of energy that it can store. The unit of capacitance is the farad. Of all types of capacitors, electrolytic capacitors, as well as their further improved relatives, ionistors, have the largest capacity.
To understand why a capacitor is needed, let's figure out what happens in the car's electrical network when low-frequency car audio with a power of 1 kW or more is turned on. A simple calculation shows that the current consumed by such devices reaches 100 amperes and more. The load has an uneven character, the maxima are reached at the moments of bass beats. The voltage drop at the moment the car audio passes the peak of the bass volume is due to two factors:
- The presence of internal resistance of the battery, limiting its ability to quickly output current;
- The influence of the resistance of the connecting wires, causing a voltage drop.
A battery and a capacitor are functionally similar. Both devices are capable of accumulating electrical energy, subsequently giving it to the load. The capacitor does this much faster and more “willingly” than the battery. This property underlies the idea of its application.
The capacitor is connected in parallel with the battery. With a sharp increase in current consumption, the voltage drop across the internal resistance of the battery increases and, accordingly, decreases at the output terminals. At this point, the capacitor is switched on. It releases the accumulated energy, and thereby compensates for the drop in output power.
How to choose a capacitor
The required capacitance depends on the power of the subwoofer. In order not to go into complex calculations, you can use a simple rule of thumb: for 1 kW of power, you need a capacitance of 1 farad. Exceeding this ratio is only beneficial. Therefore, the most common 1 farad high-capacity capacitor on the market can also be used for subwoofers with a power of less than 1 kW. The operating voltage of the capacitor must be at least 14 - 18 volts. Some models are equipped with a digital voltmeter - indicator. This creates additional convenience in operation, and the electronics that controls the charge of the capacitor makes this procedure easier.
How to connect a capacitor to a subwoofer
Installing a capacitor is not a complicated procedure, but when performing it, you need to be careful and follow some rules:
- To avoid a noticeable voltage drop, the wires connecting the capacitor and the amplifier should not be longer than 50 cm. For the same reason, the cross section of the wires must be chosen large enough;
- Polarity must be observed. The positive wire from the battery is connected to the positive power terminal of the subwoofer amplifier and to the capacitor terminal marked with a “+” sign. The output of the capacitor with the designation "-" is connected to the car body and to the negative power terminal of the amplifier. If the amplifier has already been connected to ground before, the negative terminal of the capacitor can be clamped with the same nut, while maintaining the length of the wires from the capacitor to the amplifier within the specified limits of 50 cm;
- When connecting a capacitor for an amplifier, it is better to use standard clamps for connecting wires to its terminals. If they are not provided, you can use soldering. Twisting connections should be avoided, the current through the capacitor is significant.
Figure 1 illustrates connecting a capacitor to a subwoofer.
How to charge a capacitor for a subwoofer
To connect to the car's electrical network, an already charged car capacitor should be used. The need to perform this action is explained by the properties of the capacitor, which were mentioned above. The capacitor charges as quickly as it discharges. Therefore, at the moment the discharged capacitor is turned on, the current load will be too large.
If the purchased capacitor for the subwoofer is equipped with electronics that control the charging current, you can not worry, feel free to connect it to the power circuits. Otherwise, the capacitor should be charged prior to connection, limiting the current. It is convenient to use an ordinary car light bulb for this by turning it on against the power circuit. Figure 2 shows how to properly charge large capacitors.
At the moment of switching on, the lamp will light up in full heat. The maximum current surge will be limited by the power of the lamp and will be equal to its rated current. Further, in the process of charging, the incandescence of the lamp will weaken. At the end of the charging process, the lamp will turn off. After that, you need to disconnect the capacitor from the charging circuit. Then you can connect the charged capacitor to the power supply circuit of the amplifier.
If after reading the article you still have questions about the connection, we recommend that you read the article "How to connect an amplifier in a car."
Additional benefits of installing capacitors in cars
In addition to solving problems with the operation of the subwoofer, a capacitor connected to the car's network has a positive effect on the operation of electrical equipment as a whole. It manifests itself as follows:
- The capacitor is a good filter for the high-frequency components of the mains voltage that occur during the switching of loads and the operation of some electronic devices, its functions favorably affect the operation of all vehicle systems;
- The use of a capacitor makes it possible to smooth out voltage surges that occur when consumers of the on-board network are turned on and off, which allows the generator to work in a more even mode;
- When starting the car with a starter, the capacitor, of course, takes an additional part in it, giving its charge to the on-board network. This is especially true in winter, when the ability of the battery to give current is reduced, and the properties of the capacitor do not change.
The condenser is installed and you notice that your subwoofer has started to play more interestingly. But if you try a little, you can make it play even better, we suggest that you read the article "How to set up a subwoofer".
Conclusion
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