What Is Speaker Impedance?

Understanding Hi-Fi Speaker Impedance and Its Role with Amplifiers

When you start exploring the world of high-fidelity (hi-fi) audio, you may come across terms like speaker impedance and nominal impedance. These concepts are crucial for getting the best sound out of your audio system. Let’s dive into what speaker impedance is and how it interacts with amplifiers.

What is Speaker Impedance?

Speaker impedance is a measure of how much the speaker resists the electrical current sent by the amplifier. It’s measured in Ohms (Ω). Think of it as the electrical resistance the speaker presents to the amplifier. The impedance is a curve that changes with frequency and it is not static. 

Nominal Impedance

Nominal impedance is the value of speaker impedance commonly specified by manufacturers. It represents the average impedance over the frequency range the speaker operates in. For example, you might see speakers labeled as having a nominal impedance of 4 ohms, 6 ohms, or 8 ohms.

What Does Speaker Impedance Mean for Amplifiers?

When you connect a speaker to an amplifier, the amplifier sends an electrical signal to the speaker to produce sound. The impedance of the speaker affects how much electrical current the amplifier needs to deliver to produce a certain volume level.

Amplifiers are designed to work with specific ranges of speaker impedance. They have a rated minimum and maximum impedance they can safely drive. If the speaker’s impedance is too low or too high for the amplifier, it can cause problems.

Understanding Speaker Impedance Matching

Ideally, you want to match the impedance of your speakers to the amplifier’s recommended impedance range. If the impedance is mismatched, it can result in:

Low Impedance (Below the Rated Minimum): This can cause the amplifier to deliver more current than it’s designed for, potentially overheating the amplifier and causing distortion or even damage.

High Impedance (Above the Rated Maximum): While less problematic than low impedance, high impedance can cause the amplifier to not deliver enough power to the speakers, resulting in lower volume levels and potentially affecting sound quality. (very rare)

What Happens When Impedances Don’t Match?

If you connect speakers with a lower impedance than the amplifier is rated for, you risk damaging the amplifier. The amplifier will struggle to handle the extra current demand, leading to overheating and distortion.

On the other hand, if you connect speakers with a higher impedance than the amplifier is rated for, you may not get the optimal power output from the amplifier. This can result in lower volume levels and less dynamic sound.

Can I connect my 4 Ohm speakers to my 8 Ohm amplifier?!

The short answer (TLDR): absolutely YES!

All of our Arendal Sound Speakers are 4Ohm nominal.

The actual impedance varies with frequency. It is not a constant.

You can see this here in the measured impedance curve.

Only a small section dips below 5Ohm.

The majority of today’s amplifiers or AV-receivers, even entry-level ones, are stable enough to handle loads below 4Ohm.

Combined with a good sensitivity this means a very easy load for the amplifier.

Impedance switch

Always leave the switch or setting in 8Ohm/high mode!

This will give you the full power output with no restrictions.

The exceptions are tube amplifiers. There you have to experiment with which output sounds best.

Manufacturers implemented this function to get a 4Ohm rating for a certain device temperature.

This is important to get a certification in some countries.

But all it does is limit the power and you risk getting into clipping much sooner, which can damage your speakers or amp.

The only thing you need to keep in mind is to monitor the temperature. Always give your amp room to breathe.

Other than that there is nothing to worry about.


Understanding speaker impedance is essential for building a high-quality audio system. Matching the impedance of your speakers to your amplifier’s recommended impedance range ensures optimal performance and prevents damage to your equipment. Always check the specifications of your amplifier and speakers to ensure they are compatible. All our speakers have a 4 Ohm nominal impedance, like most speakers on the market, and will work with most amplifiers and AVRs. 
If you are unsure, please reach out to our support team: sales@arendalsound.com.