Impedance Guide for Speakers: Speaker Impedance Matching with Audio Components

When you are thinking of buying speakers to enrich your sound system, you need to have some basic knowledge about different things of speakers before buying them. Without knowing them you might end up buying speakers that don’t go well with your needs and preferences. That’s why you should understand this Impedance Guide for Speakers.

And there are things you must take into consideration so that you can buy speakers that will perfectly with your home system and also with your demands. And one of the most important things to know about speakers before buying one is the impedance of speakers. This article can help you to understand speaker impedance more.

Understanding Impedance of Speakers 

Speaker impedance is a bit complex thing to understand, so people, in general, tend to ignore it or misunderstand it. When you want to connect multiple speakers to an amplifier, knowing about impedance comes in handy. And the basic understanding pf the impedance of speakers is not really difficult.

A speaker puts a unit of load on the amplifier, and that load is referred to as that speaker’s impedance. An amplifier supplies current to a speaker and the speaker puts a resistance to it and this resistance is speaker impedance.

The current that flows from the amplifier is AC current, and the resistance the speaker puts against it is the impedance. Actually, the impedance affects the rate of current that the speaker will draw from the amplifier.

Just like resistance, the unit used to measure impedance is ‘ohm’. The omega sign (Ω) is used to write ohm shortly.  The speaker impedance keeps changing constantly as it changes with the frequency of the amplifier, as the signals that come from the amp are music or other sounds with lots of various frequencies.

So rather than setting impedance for every different frequency, the manufactures set the nominal impedance for a speaker, which is calculated from the lowest values of the impedance of that speaker, and mainly their average is set as the impedance. Nominally most speakers are rated at 4Ω, 6Ω, 8Ω, or 16Ω by the manufacturers.

But most speakers are rated between 4 to 8 ohms these days, not more than that. We have known earlier that impedance is a kind of resistance which resists the flow of current from the receiver or the amplifier, so we can say that the lower the ohm of the impedance is, the more current it will draw from the amplifier,

And in the same way, the higher the ohm of the impedance is, the less current can flow to the speaker and it will run with less power. You can easily say that the 8 ohm one runs with less power than the 4 ohm one. And there are reasons for having an impedance of different rates.

Speaker Impedance Specifications

So we stated earlier that depending on the frequencies the speaker is producing, the impedance of the speaker will widely vary. But a definite impedance has to be set to the speaker while manufacturing, so a nominal impedance is set which is basically the average of the smallest of the impedance rates.

And we have also known that most speakers’ impedance is set at 4-8 ohm. We know about bookshelf speakers and tower speakers. These speakers mostly have an impedance rate of 6 or 8 ohms.

If a speaker has 4 ohms as its impedance it surely is an audiophile and high-end speaker, which will draw more power from the amplifier, so it will generally want to be connected with a powerful amp. This kind of speakers can produce huge sound as they use a lot of power in order to produce sound.

And the lower the impedance rate your speaker will have the more powerful amp you will need and the more you can get your desired sound. Also having a lower impedance rate opens up an area of vast design choices and opportunities.

But if we round up the market numbers and analyze the data of speaker buys, we will see that most of the people tend to buy speakers which have an impedance of 6 or 8 ohms. The reason is these types of speakers are more suited or particularly can balance more with the kind of designs most of AV receivers have these days.

Though this statement can’t be taken as universal, as people think of many other things other than impedance while buying speakers. But still, you should have knowledge about amps and impedance ratings while buying a speaker and be aware of these things and choose carefully according to the impedance-amp rule.

How to Measure the Impedance of Speakers

Measuring the impedance of a speaker is not really an easy task. Cause unlike resistance, impedance keeps changing with frequency. So the measurement is actually more like a graph, not a normal calculation.

These days you can find specialized equipment that can automatically create the graph and measure the impedance within a second. But we can measure the impedance another way. For this, we will mainly need a multi-meter or an ohmmeter. Then we can do the following step by step-

At first switch, the meter on and then set it to its lowest range which includes units of one. Then, to prevent incorrect readings induced by other resistances that might be associated, detach one or both speaker wires from the speaker.

Then, tightly press the probes against a clean metal spot between the speaker terminals. The meter would then take a fast reading. The meter will then show the resistance of the voice coil, which is located within the speaker. The measured value is then used to calculate the speaker’s nearest estimated impedance.

For some speakers which are placed inside an enclosure or cabinet or two-way speakers, this reading might have interfered as crossovers might be in use. However, you will be able to measure the impedance pretty fairly.

You have to remember an important thing. Exactly 4 ohms, 8 ohms, etc won’t be measured, as speakers are normally given an impedance rating that is approximate to what you’ll measure with the multi-meter, for stereo purposes.

And don’t forget to use the correct range of resistance on the meter while measuring the speaker impedance. Cause the wrong setting can totally ruin your reading of the meter.  Thus you can measure the impedance of a meter.

Connecting Multiple Speakers

When you try to connect multiple speakers who don’t match with each other in systems with the amplifier, a mismatch happens and the amplifier can’t take it. As a result, the amplifier gets turned way up and then it can not handle the load at all.

This generally happens when someone tries to fill a larger room with powerful sounds and ends up getting multiple speakers, but fails to get matched speakers and amplifiers. And when mismatched multiple 6 or 8 ohms speakers get connected to the amp which is not up to the task, the amp can’t take it and ends up getting cankered. Also Understand speaker placement to get more details.

So in order to make things work perfectly, you should not only match the speakers’ impedance with the capability of the amplifier or the receiver, you should also try matching the whole sound system of the room.

But the bottom line is, you really should match the speaker’s impedance with the capability of the receiver you are using so that it can run smoothly without causing any problems.

Matching the Impedance with Amplifier

There is a switch on your receiver which can limit the output of power. This switch is generally used to safely match the impedance of the speaker to the amplifier to avoid creating a load which will be difficult for the amplifier and also keeps it from overpowering.

One can change it between 4-8 or 6-12 ohms, depending on the brand. However, there are little problems. The thing is, impedance curves of loudspeakers aren’t flat. They change continuously, sometimes they get very high, and the next moment they get really low.

So if you set it to a low range, it might spend a lot of time with a high range which can be problematic. Also if you use subwoofers, the range might remain high most of the time. So you can play it safe by limiting the power output of the receiver or if you want the most powerful output, you can set it to the highest setting, whichever suits you most.

So, you must cautiously use the switch and make sure that the switch position is matching with your speaker’s impedance perfectly. You can also find out about the Power Amplifier and Integrated Amplifier.

Consequences of High and Low Impedance

Well, there are some notable consequences of having both lower and higher impedance. If the higher impedance is used the equipment will be safe from getting damaged. And as a lower power will be drawn from the amplifier, the volume of the speaker will be lower.

Crossovers of speakers can be problematic. But you can save power with this. On the other hand, if a lower impedance is used, it can cause the equipment to suffer extreme heat and they might suffer some small or big damage.

The reason is the output will be much more than it can take. But with a reasonable high impedance, you can have a great and powerful sound from your speaker. But power-saving won’t be possible.


So, from the above article, we can know what the impedance of a speaker is, how it actually works, and why knowing about it is important. Hope this article will also help you to determine which kind of impedance rate you want to have for your speaker.

Remember to choose the speaker with the most preferable impedance rate according to the system you have. Also find out How to choose amplifier for speakers: Complete buying guide