Can I Hook Up 8 Ohm Speakers To a 4 Ohm Amplifier?

Norvan Martin

Poor impedance matching between your amplifier and speakers can cause several problems, including excessive clipping and damage to both speaker and amplifier. It can also negatively affect the quality of the sound you get.

So, can you hook up a 4 ohm amplifier with 8 ohm speakers?

Yes, you can use 8 ohm speakers with a 4 ohm amplifier if you connect two speakers in parallel. This will not cause clipping and will not damage your speakers or amp. However, it will result in less power output for each speaker, but not much distortion.

How do you connect two 8 ohm speakers to a 4 ohm amplifier?

  • Wire two 8 ohm speakers of the same wattage in parallel to connect them to a 4 ohm amp.
  • Be cautious! Wiring more than two 8 ohm speakers in parallel risks damaging the amp.
  • Reversing this mismatch (4 ohm speakers with an 8 ohm amp) can lead to significant issues like excessive heat buildup in the amp’s output and potential amp damage.

Wire 8 Ohm Speakers in Parallel

Wiring 8 ohm speakers to a 4 ohm amplifier in parallel can reduce the impedance, ensuring the speakers don’t add an excessive load to the amp:

  • Wiring in parallel halves the impedance to 4 ohms, matching a 4 ohm amp.
  • For speakers with common impedance, the overall impedance can be found by dividing the common impedance by the number of speakers.
  • For non-common impedances, a specific formula is used as shown below:
speaker impedance in parallel

Illustration: Here’s how you can wire your speakers in parallel:

can i hook up 8-ohm speakers to a 4-ohm amplifier

Considerations when wiring multiple speakers in parallel:

  • Each additional speaker in parallel reduces impedance by half.
  • Combining 4 ohm and 8 ohm speakers is possible, but the wiring arrangement must ensure the overall impedance isn’t too low compared to the amplifier.
  • Mistakenly reducing impedance below the amp’s nominal can cause the amp to blow due to excessive power demand from the speakers.

Note:

8 ohm speakers on a 4 ohm amp only need to be rated at half the amp’s output power. For example, an 8 ohm speaker with a 100 watt max input equates to a 4 ohm speaker with a 100 watt max input. The lower the impedance, the more power a speaker should handle. Thus, halving the impedance can double the power, provided the amp doesn’t run out of current.

What is Impedance and Why Does it Matter?

To answer the question above correctly, we need to understand what constitutes impedance.

For every amp and speaker you buy, you will find the impedance indicated in ohms (Ω), and you need to understand the significance of this figure to minimize the risk of damage. For example, you need to understand the difference between 4 ohm and 8 ohm speakers.

What Is Impedance Matching?

Impedance refers to the degree of resistance a circuit or an electronic component within a circuit offers to electrical current. So, a higher ohm implies the circuit offers more significant opposition to the flow of electric power.

Impedance Matching 4 ohm amp with 8 ohm speaker

Impedance matching refers to matching the impedance of the amp with the overall impedance of the connected speakers. For maximum wattage or power transfer to the speakers, the speaker’s resistance must equal the amplifier’s resistance.

Speaker Impedance and Amp Damage

Higher impedance opposing current flow can be good news if your audio system requires little current to function and the circuit impedes the free flow of charge.

On the other hand, if you ignore the basic rules of impedance matching, you might supply inadequate current to your speakers. However, the speakers will still demand the current they require. This can blow out the entire system.

This means that lower speaker impedance will put a heavy load on the amp because low-impedance speakers will demand a lot of power from the amp.

Nominal Impedance

Another essential thing to note is that the indicated ohm is a nominal value, which is the average impedance of the speakers. The impedance of any system (amp, speakers, etc.) will vary within a small range for several reasons, including temperature and frequency.

As such, we use the term nominal impedance to refer to the average impedance value of the speaker or amplifier. You need to keep this in mind when trying to match the impedances of your 4 ohm amplifier and 8 ohm speakers. Impedance matching is explained below.

We can say that the resistance to the flow of current varies depending on the speaker’s frequencies at different moments. For example, an 8-ohm speaker might operate as a 10-ohm device at some stage along the frequency spectrum. At other moments, it can be 7 ohms or even 11 ohms. Another example is a speaker that is rated as 4 ohms and can vary from 2 ohms to 8 ohms at any given time.

The best solution to this issue is to use a speaker designed to meet your impedance needs (impedance matching).

Speaker Wiring (Series and Parallel) and Impedance

Wiring also affects speaker impedance. Wiring speakers in series will add up the overall impedance. This means that for two 8 ohm speakers, the total load on the amplifier will be 16 ohms. More ohms means you lessen the likelihood of damage, but the speakers will operate at less power.

wiring 8 ohm speakers to 4 ohm amp in series
Total load is 8 ohms (8 + 8 = 16 ohms)

On the other hand, wiring speakers in parallel decreases the impedance. For example, wiring two speakers in parallel halves the impedance.

wiring 8 ohm speakers to 4 ohm amp in parallel
Total load is 4 ohms (8 + 8 / 2 = 4 ohms)

To find the resulting impedance of speakers wired in parallel, simply divide the impedance by the number of speakers in parallel. For example, if you have two 8 ohm speakers in parallel, 8 divided by 2 = 4 ohms.

FAQs

How To Hook Up 8-ohm Speakers To A 4-ohm Amplifier

Yes, a 4 ohm amp can handle 8 ohm speakers if it is a single 8 ohm speaker or the overall impedance of multiple 8 ohm speakers is 4 ohms or more.

If you have multiple 8 ohm speakers, you need to determine what the overall impedance is. While some people manage to wire multiple 8 ohm speakers to equal 8 ohms, in most cases, the overall impedance will be more than 8 ohms if the speakers are connected in series and less than 8 ohms if the speakers are connected in parallel. Some people wire two 8 ohm speakers to equal 4 ohms and so on.

The impedance of your amplifier and the impedance of your speakers are two different things. However, to determine whether we can use an amp and speakers safely, we need to consider the amount of load that the speakers put on the amp.

Low Amplifier Impedance

Let’s say the amp has a lower impedance than the speakers. This means the amplifier can supply more current than the speakers require.

Given that modern speakers can handle a high supply of power, nothing will likely happen if you run the amp to the speakers. You will get good-quality sound.

High Amplifier Impedance

However, that would not be the case if the amp had a higher impedance than the speakers.

Remember, we said that the assigned impedance is a nominal value. So, the amp’s ohm can significantly increase.

The same applies to the speakers. Impedance changes as the frequencies increase or decrease.

Given that the difference between 4 ohm and 8 ohm is small, you do not need to worry about their maximum sound pressure level (SPL). The chances are that your speaker can cope with the supplied power.

However, since 8 ohm doesn’t fall within the amp’s impedance range, you should exercise caution. Keep the volume low.

In this case, improper impedance can damage the speaker coil or blow the amp, particularly if you fail to control the frequencies. This reminds us why impedance matching is important. Despite the low risk, you need to do due diligence and not damage the speakers and amp.

What Happens if You Use 8 Ohm Speakers On a 4 Ohm Receiver?

If you use 8-ohm speakers on 4-ohm receivers, you’ll get high-quality audio. The receiver will supply more power than the speaker requires. Since modern speakers are designed to handle an excessive power supply, nothing harmful will happen.

However, if you use 4-ohm speakers on an 8-ohm receiver, your receiver might fail to supply adequate power, leading to sound quality issues. In some cases, the shortage of power can damage your speakers and the receiver.

What Amplifier Do I Need For 8 Ohm Speakers?

Speakers with a nominal impedance of 8 ohms and a program power rating of 350 watts require a receiver or amp that produces 700 watts into an 8-ohm load. So, the amp should be rated 700 watts per channel with an impedance of 8 ohms.

Can I Use the Impedance Switch to Match the Impedance?

If your amp features an impedance switch, you may want to use it to adjust the ohm settings to match the eight-ohm speakers. Many manufacturers recommend it. Nonetheless, it is not the best solution.

As we have said, impedance is not static. It keeps changing depending on the speakers’ frequency. If you use the switch, you limit the amp’s ability to assign the most suitable impedance.

For example, when the actual impedance needs to be 6 ohms, you will likely switch it to 8 ohms or something closer to that. To learn more, check out this guide on 6 ohm vs 8 ohm speakers. This way, you intentionally cripple the amplifier’s capacity.

The above point is another reason you should not tamper with the speakers’ impedance rating if you want the best performance. Instead, buy amps that match the system’s impedance settings.

Does Impedance Matching Guarantee the Best Experience?

We have seen that you can get excellent quality if you match impedance. Nonetheless, it doesn’t guarantee the best experience.

Opting for low or high-impedance speakers may not serve your needs, especially if you do not understand speaker sensitivity, which many beginners often ignore.

Speaker sensitivity refers to the ability or efficiency of the loudspeaker to convert the amp’s power to acoustic energy. For that matter, it determines how loud your loudspeaker will be for a specific amp power.

While some people think that speaker sensitivity is a complex concept, that is not true. Generally, independent consultants and manufacturers will often measure speaker sensitivity. Nonetheless, you can do it as well.

The primary way to measure it is to use a calibrated sound level meter. To be consistent, you should measure sensitivity 1 meter from the loudspeaker while one watt of power originates from the amp.

Whenever looking for speaker specifications, pay attention to something that looks like this: Sensitivity: 87dB (1w/1m). It shows the loudness level that the speaker can produce when you drive it with 1 watt of power and measures the performance one meter in front.

When comparing sensitivity, remember that different speaker designers and manufacturers may arrive at the figures differently. So, it is best to compare speakers from specific brands differently. You may also need to read the user manuals to determine what makes the speakers’ sensitivity unique.

Overall, speaker sensitivity will help you to know:

  • How loud your loudspeaker can be
  • The efficiency of the amp that you need

Speaker sensitivity doesn’t determine the quality or lack of quality of your devices. It also doesn’t determine the sound quality, but you must consider it if you are concerned about your speakers’ loudness.

Matching Amplifier to Speakers Wattage (Power)

As an unspoken rule of thumb, you should choose an amplifier that can produce double the continuous power rating of a speaker.

This means that a speaker with an 8-ohm “nominal impedance” and a 350-watt program rating will need a 700-watt amplifier to drive this 8-ohm load.

Sometimes, it is even advisable to use an amp that supplies 2 to 4 times the speaker’s continuous power rating per channel.

This leaves 3 to 6 dB of headroom for audio signal peaks. Short-term peaks can be handled by speakers in most designs. The goal is to have enough clean power so the amp can take whatever you throw at it without clipping.

However, if you are limited in terms of budget or the availability of powerful amplifiers, you can use an amplifier close to the power rating of the speakers, but ensure that you do not max out the volume. Keep the volume low.

Check out our guide on speaker and amplifier wattage to learn more about speaker and amplifier wattage matching.

Wrap Up

When running a 4-ohm amp to 8-ohm speakers, you should be just fine if you keep the overall impedance of the speakers at least 4 ohms.

However, you should opt for a speaker with the desired sensitivity and match the impedance for the best performance.

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Norvan Martin is the founder of BoomSpeaker.com. He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics. My email: [email protected]  Connect on Pinterest and Linkedin