Speakers just like amplifier outputs have an impedance rating which is an electrical property similar to resistance. Speakers come with different impedance ratings and by matching the impedance of your speakers to your amplifier, you’ll ensure that your audio system will produce the best sound and run efficiently.
So, can I connect 8-ohm speakers to a 4-ohm amplifier? Yes, a 4-ohm amplifier can handle 8-ohm speakers when it’s a single 8-ohm speaker or when the overall impedance of the 8-ohm speakers is 4-ohms or more. You’ll get high-quality audio since the amplifier will deliver more power than the speakers need and since modern speakers are designed to handle more power supply, they won’t get damaged. If you have multiple 8-ohm speakers, you’ll need to determine their overall impedance. If you wire more 8-ohm speakers that are equivalent to 8 ohms, most likely the overall impedance will be more than 8 ohms if the speakers are connected in a series, but if they’re connected in parallel, it will be less than 8 ohms.
The impedance of your speakers and that of your amplifier is very different. However, for you to use your amplifier and speakers safely you need to consider the amount of load your speakers put on your amplifier.
High amplifier impedance
As the frequencies increase the drop impedance changes. Since there’s a small difference between the 4 ohms and 8 ohms, you don’t have to worry about their maximum sound pressure level or SPL since your speakers will work with the supplied power. However, 8-ohm isn’t within the impedance range, you should keep the volume low. Improper impedance can cause damage to the speaker coil or blow the amplifier, especially if you don’t control the frequencies. Although its low risk, you should exercise caution.
Low amplifier impedance
If your amplifier has a lower impedance than your speakers, this means your amplifier will supply more power to the speakers than they need. However, modern speakers can now handle excessive power supply and still produce good quality sound.
Like resistance, impedance is a restriction of the flow of the electric current in the circuit. Resistance and impedance are similar, but impedance changes depending on the audio frequencies while resistance is generally constant. Ohms is what measures resistance. Audio amplifiers are mostly designed to work with 4, 8, and 16 ohms of resistance, and to get optimal performance from your audio system, the total ohm load of the speakers should be the right one for the amplifier.
If the total speaker impedance is too low, the power delivered to the speakers will be higher and this can damage the amplifier and overload the speakers. You can connect many speakers to one amplifier provided they have been wired properly and they don’t all fall below the specified output impedance of the amplifier. Dual speaker connections on an amplifier or a speaker are all done in parallel.
Here’s what you should know to help you match the impedance of the speakers to the amplifier to avoid overloads and ensure great performance.
Series and parallel connections
If you connect 2 or more speakers to the same amplifier output, the total impedance of the speaker set changes. You can either wire the speakers in series or parallel. Speakers that have been connected using a series connection combine their impedance so, if 4-ohm speakers are wired in series this adds up to 8 ohms in total. When the speakers are connected in parallel, the outcome is more complex which means you multiple each impedance for the 2 speakers, then divide the sum by the total of the impedances.
|Series connection||Parallel connection|
|The flow of current is the same throughout all the speakers in the circuit||The circuit has 2 or more current flow paths|
|A fault at one point in the circuit breaks the whole circuit||If one speaker gets damaged, the current doesn’t stop. It continues through the other speakers|
|All the speakers are arranged in a single line||The speakers are arranged parallel to each other|
Are speakers louder in series or parallel?
Generally, speakers in parallel are louder than those in series because the series speakers only receive a part of the power delivered which has less driving power than that in the parallel speakers. By wiring your speakers in series, you increase the total ohms load of the speakers and this decreases the electric current that can flow so the amplifier output power is lower.
When you’re connecting 2 speakers in series, if you have 2 speakers in series, the speaker with the higher impedance will take more power, but if your speakers are in parallel, the speaker with the higher impedance takes less power. However, you have to keep in mind that if the 2 speakers have the same power rating, one of them will tend to hog more power than the other and this makes the combined power rating higher which puts one speaker at risk of failure.
Can I use the impedance switch to match the impedance?
If your amplifier comes with an impedance switch, you can use it to adjust the ohms settings so that you can match it with the 8 ohms speakers. However, impedance isn’t static which means it will change depending on the speaker’s frequency. So if you use the switch, you’ll limit your amplifier’s ability to find the most suitable impedance. This way you intentionally cripple your amplifier’s ability and this will affect its performance.
You can run 8-ohm speakers to a 4-ohm amplifier provided you keep the speaker’s overall impedance at 4 ohms. Just wire two 8 ohm speakers of the same wattage in parallel so that the output impedance of the amplifier matches and has the same wattage as the 2 speakers.
What amplifier do I need for 8-ohm speakers?
Speakers with an impedance of 8 ohms and a power rating of 300W will need an amplifier that can produce 700W into an 8-ohm load.
Which is louder, a 4 ohm or an 8-ohm speaker?
A 4-ohm speaker will need more power from the amplifier than the 8-ohm speaker to produce the same loudness of sound.