Impedance is one of the main characteristics of any speaker, along with power or loudness. In this guide, you will get speaker impedance explained without diving into the complex technical nuances.
You will find the impedance values in the manual for any modern speaker. It is measured in ohms and denoted by the Greek letter Ω. Well, now let’s take a closer look at what it is.
What is speaker impedance?
Technically speaking, impedance measures the resistance a speaker puts on to an alternating current flowing through an amplifier. Or, in other words, the load that the speakers put on the amplifier.
But we agreed not to go into technical details too deeply, so let’s consider an analogy that everyone can understand.
Imagine that your speaker is an ordinary water pipe, only instead of water, a sound signal passes through it. Agree that the wider the pipe is, the easier it will be for the water to flow and the more volume of this water it can pass through. So the impedance is the width of this same pipe, only in the opposite direction. The lower it is, the broader our imaginary pipe will be.
The lower the impedance value of the speaker is, the easier the electrical signal will pass through it. However, for speaker impedance matching, you should know that it changes depending on the transmitted signal’s frequency. Therefore, the manufacturers indicate the nominal value of this parameter. This is the average value at different frequencies. It ranges from 4 to 16 ohms.
Difference between resistance and impedance
Impedance and resistance are practically the same things. These parameters indicate how difficult it is for an electrical signal to pass through a circuit.
The only difference is what type of electric current they use. Resistance is indicated when DC (direct current) is applied. In turn, impedance is indicated when using AC (alternating current). We use the impedance value when talking about the speakers because the amplifier sends alternating current to them.
With DC, the resistance is a constant indicator. But with AC, it depends on the frequency of the signal. This is the main difference between these concepts, and this is sometimes the speaker specifications show the impedance range.
Why do I need to pay attention to speaker impedance?
We have come to probably the central question of our guide. So, why is the impedance value so important to us?
When assembling a home audio system, it is essential that the components are compatible with each other. The impedance value tells us exactly how the speakers and amplifier will work together. Although impedance is only for speakers, you can see this parameter in the amplifier specification as well. It indicates which impedance speakers are suitable for this amp model.
You can use speakers of any impedance with any amplifier. And this system will even work and will not explode as soon as you turn it on.
However, running 4-Ohm speakers on an 8-Ohm receiver is not the best idea. And that is why – when the amplifier is not suitable for driving low impedance speakers, it will draw significantly more power than it is rated for. As a consequence, it is likely to overheat and shut down.
If the specification of your amplifier specifies an impedance range of 4-8 ohms, then the best choice would be to buy speakers with 4, 6, or 8-ohms. In the 6-8-ohm range, it is better to choose 6 or 8-ohm speakers than 4. Of course, you can connect 4-ohm speakers, but we have already discussed the amplifier’s risk of overheating. There is also a considerable risk of damaging the speakers before the amplifier has time to turn off.
If you think “can I hook up 8-Ohm speakers to a 4-ohm amplifier”, then the answer is definitely yes. In this case, the safe operation of both devices is guaranteed. But you will not use the amplifier’s capabilities to the full.
Do low-impedance speakers provide high-quality sound?
The short answer to this question is yes. This is because speakers with a lower impedance produce better sound quality than speakers with a higher value. However, there are several points that are also worth considering.
Firstly, 4-ohm speakers (and these are the lowest impedance speakers on the market) require a powerful amplifier, which is designed for high loads, to work correctly. Using these speakers with unsuitable amplifiers can damage them.
Secondly, such a system would be a costly pleasure. In addition to the fact that you need a powerful and expensive amplifier, the price of the speakers themselves is likely to be very significant. The fact is that manufacturers mainly use 4-ohm impedance only in top-end flagship models. Such speakers will be pretty expensive.
4-ohm impedance speakers provide very clear quality sound, but a more budgetary alternative is available. You should pay attention to the sensitivity indicator. After all, speakers with a higher impedance and a higher sensitivity can show almost the same result.
How to choose the right impedance for my audio system
It all depends on the result you want and the budget you are willing to spend.
If you are ready to spend a lot, but you want to get high-quality sound, then your choice is 4-ohm speakers and the amplifier that supports them. On the other hand, if you have a budget audio system, then 6-8 ohm speakers are the best option not to overload the amplifier.
Do I need to change the impedance settings on my receiver?
Many high-tech amplifiers allow you to set the impedance value manually. This can be done either in the setup menu or using a switch on the control panel.
In the manual of such amplifiers, it is better to set this parameter in accordance with the connected speakers. If you connect 4-ohm speakers, set the same impedance in the amplifier settings, and so on. In theory, this should ensure proper current flow to your speakers.
But what happens in practice? You need to be aware that the impedance is not a static indicator but a constantly changing quantity. Depending on the frequency of the sound, its meaning also changes. Therefore, manually setting the impedance will limit the capabilities of your amplifier. You will lower the amplifier’s power, reduce the amount of current passed to the speakers, and the more likely you will get distorted sound.
Therefore, in such a situation, you need to ensure that your amplifier and speakers have a compatible impedance and set it to the default value. This is usually 8 ohms. This will ensure optimum sound from your system.
Finally, let’s go over the main points about speaker impedance.
Most modern audio components are compatible with each other by default. So it is unlikely that you will buy an amplifier and speakers that ultimately cannot work together. But to get excellent sound quality, you should select the equipment for consistency, and impedance is one of the indicators that you need to pay attention to.
An amplifier designed for low impedance will easily cope with a higher impedance, but in the opposite direction, there can be problems. Therefore, ensure that your amplifier can handle the load when buying a 4-ohm speaker or speaker with an impedance other than the standard 4-16-ohm range.
Audiophile speakers with an impedance of 4 ohms with a suitable amplifier will give the best sound quality, but you will have to fork out decently to purchase. For more budgetary systems, speakers with 6-8 ohms are suitable.