Impedance is a measurement of the electrical resistance that a speaker will put up against the electrical current that come out of the amplifier. Impedance is measured in unit of ohms. The higher the impedance value of a speaker, the more resistantly it will put up against the current from the amplifier.
A low impedance value mean the speaker will offer low resistance to the electrical current from the amplifier. A high impedance value means the speaker will offer high resistance to the current from the amplifier. Understanding the impedance of a speaker will help people to understand the amount of work that the amplifier will have to do to operate the speaker.
What Is Speaker Impedance and Why It Matters
If a speaker has a low impedance, the amplifier will have to work harder to power that speaker. This is because a low impedance allow more current to flow through the amplifier. If the impedance of a speaker is too low for an amplifier that was not design to handle such a low impedance, the amplifier can overheat due to the high current that is flowing through it.
Overheating can damage the equipment and cause speaker failure. Therefore, it is important to ensure that the impedance of the speaker that is being use is compatible with the amplifier. Not all environment require the same impedance ratings.
For example, speakers in home audio systems usually have high impedance rating because the audio systems in homes can better handle high impedance. Car audio systems has speakers with low impedance ratings because car audio amplifiers are designed to work with the power provided by the car’s 12-volt battery. Many people prefers the comfort of using high impedance speakers in there home audio systems because these speakers are more easier for the home audio amplifier to work with without overheating.
The wiring of the speakers can change the total impedance of a system. If speakers are wired in parallel, all of the positive terminal of the speakers will be connected together and all of the negative terminals will be connected together. Wiring speakers in parallel will decrease the total impedance of the system.
This will make the amplifier work harder to power the speakers. Wiring speakers in series will increase the total impedance of the system. This is a safer alternative for the amplifier, although it may result in a lower total volume level that is radiate by the speakers.
Some speaker come with what is known as dual voice coil subwoofers that allow for a speaker to be wired in two different ways that will allow it to have either a low or high impedance rating. When wiring dual voice coil subwoofers in parallel, each speaker will have its positive terminal connected to the positive terminal of the other speaker, and the negative terminal of each speaker will be connected to the negative terminal of the other speaker. Wiring them in series will connect the positive terminal of one speaker to the negative terminal of the other speaker.
By choosing one of these configuration, people can ensure that the impedance level is compatible with their amplifier so as to avoid overloading it. Another specification for speakers that should be considered when pairing a speaker to an amplifier is the sensitivity of the speaker. Speakers with a high sensitivity will require less power to produce loud sounds.
Therefore, connecting a speaker with high sensitivity and a low impedance to an amplifier will require an amount of power from the amplifier that may overwhelm the speaker and the amplifier itself. Speakers should be balanced with amplifiers in such a way that the impedance of the speaker is matched with the power capability of the amplifier. If an amplifier shuts off while people are listening to music through that device, it could be suffering from a thermal shutdown.
This usually occurs if the impedance of the speaker is too low for the amplifier to handle. A multimeter can be used to check the impedance of the speaker. This will tell people the actual impedance of the speaker.
This may read slightly lower than the impedance rating of the speaker that is printed on the speaker box. For the best performance of both device, the impedance of the speaker should be matched with the amplifier requirement so that it does not overheat and functions for long period of time.