(Last Updated On: November 14, 2020)

When building a home audio system on a budget, you may need to connect multiple speakers to one amplifier.

However, connecting multiple speakers to an amplifier may prove a bit challenging. You may encounter a few issues, especially if you have no experience in this area.

Multiple Speakers On A Single Amplifier

It is important to first realize that by connecting more than one speaker to an amplifier, you are virtually making the amplifier handle more power than using a single unit.

One common configuration is connecting 4 speakers to a 2 channel amp. For example, two similar speakers will double the electric load of your amplifier.

The good news is that most amplifiers can comfortably handle the output of two speakers of similar power requirements.

Multiple Speakers On A Single Amplifier

While most amplifiers can handle the power of two speakers of similar power requirements, they tend to overload if you add more than three speakers.

In fact, some amplifiers will encounter damage if you even connect two powerful speakers. With modern units, there is a limiting circuit that stops the amp from working if that happens. In most cases, the amplifier may blow a fuse or just turn off automatically.

Let’s explain a little further:

Speakers are electrical load devices that use electric current to generate sound. The more powerful the speaker, the greater the electrical current it will normally require.

If a speaker is connected to an amplifier, it will be pulling its power through the amplifier. Of course, the more speakers you connect to the amplifier, the more power the amplifier will need to deliver.

The more power the amplifier need to deliver, the more electrical current is required. However, every amplifier has a maximum current rating.

If you connect loud, powerful speakers or too many speakers that drive the current through the amplifier to the max, then the amplifier’s fuse will blow, or other components in the device will get damaged, bottom line, the device will simply stop working.

With all that in mind, it’s essential to note that many amplifiers can cope with several speakers connected at a low volume.

At low volumes, the speakers will not be pulling too much power. However, you will start having issues when you run the speakers at high volume.

That said, there are several ways to connect multiple speakers to an amplifier without causing damage. That mainly involves using speaker selector switches.

 

Connecting Multiple Speakers To An Amplifier Using Speaker Selector Switches

Speaker selector switches offer the simplest and safest way of connecting multiple speakers to a single amplifier.

Often cost-effective, they are suitable for multi-room installations around your home or while working with a low power amp (under 100 watts). For example, it’s a great way to connect two 8 ohm speakers to equal 8 ohms

The switch acts like a splitter or a hub, allowing you to power four or even eight speakers with a single amplifier.

To use a selector switch, you simply need to connect its inputs in the right or left channel output of your amplifier.

You can then connect the speakers to the outputs of the switch to start enjoying the sound from multiple speakers. That will protect your amplifier from low impedance issues that may permanently damage the amplifier.

Let’s explain;

Electrical impedance is a measure of the degree to which current is allowed to flow through the speaker.

Connecting Multiple Speakers To An Amplifier Using Speaker Selector Switches
Image Credit: Geoff the Grey Geek

In other words, the lower the impedance, the more current the speaker will allow. To protect the amplifier, speaker selector switches use two main technologies:

 

1. Series Resistor

Series resistors are common in low-cost selector switches. The resistor (4-6 ohms) protects the amplifier against damage by maintaining the minimum resistance of the amplifier when connected to multiple speakers.

These resistors are very effective in protecting your amplifier, but they tend to get hot in high volume levels. That’s why speaker selectors that use series resistors come with air vents.

speakers and amp series

Given the amount of heat that the resistor emits, it’s obvious that there is a significant loss of energy. For that, speaker selector switches that use a series resistor have an impedance protection switch.

Series Resistor connect multiple speakers
Image Credit: Geoff the Grey Geek

The switch helps you to easily control the series resistor by either including or excluding it in the circuit.

So, how does it work?

To keep the amplifier safe, you should keep the impedance protection activated when using multiple speakers.

You can switch off the series resistors to allow direct connection with zero signal losses when using only one set of speakers or impedance matching volume control

 

2. Impedance Matching Transformer

This technology is mainly available with cutting-edge speaker selector switches designed to handle a significant amount of power.

Impedance Matching Transformer
The Thevenin equivalent is just a simplified view of the amplifier as a source. It shows its voltage and internal resistance.

The impedance matching switch multiplies the impedance of each connected speaker, keeping the total impedance at the same level as in individual speakers.

That means that they work by maintaining the safe operating load of an amplifier while circulating maximum power in the system.

When buying the connector, you will need to pay attention to the speaker connection compatible with your speakers (types of speaker connectors).

That will ensure that you pick the right speaker selector for your amplifier. Please note that the volume of the amplifier may affect the audio quality of your speakers.

Learn more about impedance matching here.

 

What If I Have Two Amps With One RCA Jack Each?

If you want to connect multiple speakers and you have two amps with one RCA jack, you can use a RCA splitter, daisy chain the connection or use a LOC. Learn more about hooking up tow amps with one RCA jack.

 

Conclusion

Depending on the amplifier rating and the impedance of your speakers, you should be able to connect a pair of speakers to a single unit easily.

However, it’s wise to use selector switches when connecting more than two speakers in a single unit. That will not only help you to connect the speakers safely, but it will also protect your amplifier from overloading.

Keep in mind that it’s not advisable to run the speakers at high volumes when connected to one amplifier.