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How to Connect 4 Speakers to a 2 Channel Amp

Have you ever thought about connecting 4 speakers to 2 channel amp? Perhaps you’re thinking that a 2 channel amplifier is designed specifically to power two drivers, so it may not be able to power 4 drivers.

But the truth is you can! And the process of setting it up is very easy. So, even if you’re a relative greenhorn when it comes to car audio, you’ll be able to accomplish this, no fuss, no muss. Just follow the simple steps below, and you’ll be able to wire 4 speakers to 2 channel amp.

Before You Get Started

Wiring speakers can be a tricky business if you’ve never done it before or if you don’t fully understand the concept. There has always been a lot of confusion concerning watts, amps and impedance — which all relate directly to ohms law and hence, speaker wiring — since people have been putting speakers and subwoofers in cars.

For that reason, a basic understanding of speaker impedance and ohms law is mandatory when connecting multiple speakers to an amplifier.

What Is Impedance and Why Should You Care?

Speaker impedance refers to the load a speaker places on an amplifier. It’s measured in ohms, and uses the Omega symbol (Ω) for shorthand.

Technically speaking, speaker impedance is the “resistance” a speaker offers to the current supplied by an amplifier. In simple terms, it affects how much current is drawn from the amplifier.

It must be noted, however, that unlike resistance, impedance isn’t constant. It keeps changing with frequency and can vary greatly. Since the amplified audio signal from an amp consists of different notes and frequencies, the speaker impedance is constantly changing.

So, instead of stating the impedance for every frequency, speaker manufactures state the “nominal” impedance, which is sort of the average of the lowest values of the speaker impedance.

Because impedance impedes (or restricts) the flow of power from amplifier to your speaker, it’s safe to say that the lower the impedance, the greater the power the amp has to produce and deliver through that speaker.

Lower the impedance → more current → greater load → increased power

Raise the impedance → less current → smaller load → decreased power

Another way of looking at it is to say the lower the impedance, the higher the load on the amp (and the harder it has to work). This is true up to the point where the amp is no longer able to produce anymore current and power. At this point, either the amp fuse will blow, the amp will bite the dust or its protection circuit will kick in and turn the amp off to prevent serious damage.

Therefore, you must always make sure to run your amp with a load impedance of less than the stated minimum (normally 4 ohms).

Why Do You Need to Know About Speaker Impedance?

When wiring multiple speakers to an amplifier, you always need to make sure the speaker impedance of any speaker (or multiple speakers) connected to the amp is within the capabilities of the amp.

Most car amplifiers in the market are designed for a total impedance load of 2-4 ohms. This means the minimum speaker impedance is 2Ω. Therefore, if you have a set of speakers with a total impedance rating of 2Ω or 4Ω, everything will work great. The lower the impedance, the greater the current flowing through the speakers. But, don’t ever use a pair of speakers with an impedance below 2 ohms.

This is a real concern when you hook up two or more speakers to one amplifier. For example, if you hook up Four 4Ω speakers in parallel (more on this down below), you’d end up with a total load impedance of only 1Ω, which is way too low for your amplifier. In this case, you should consider using 1 ohm stable amplifier.

Speaker Wiring Options

To add to the confusion, the overall impedance load of a pair of speakers depends on how these speakers are wired together — in parallel or in series, or in a combination of both.

Series Speaker Wiring

Series wiring means that the devices are wired one after the other. In other words, the positive terminal of the amplifier is wired to the positive of the first speaker, the negative of the first speaker is wired to the positive of the second speaker, and so on. The negative of the last speaker is wired back to the negative of the amplifier forming one large loop. That is to say, a plus of one to a minus of another.

When multiple speakers are wired in series, you add their impedances together to find their total impedance.

For example, two 4-ohm speakers wired in series have a total impedance of 8 ohms.

Total Impedance = Speaker I1 + Speaker I2 + Speaker I3 + …

The sum of the impedance ratings of the speakers wired in series should not exceed the impedance rating of the amplifier.

Parallel Speaker Wiring

Parallel wiring means that the terminals of each speaker are connected to the same things — plus to plus, and minus to minus forming two loops.

When multiple speakers are wired in parallel, and the impedances of all the devices are the same, their total impedance is that impedance value divided by the number of devices.

Total Impedance = Speaker Impedance / Number of speaker

For example: four 4-ohm speakers wired in parallel have a total impedance of 1 ohm.

How to Hook Up 4 Speakers to a 2 Channel Amp

Now, that we’ve explained in detail what impedance is, why it matters, and the different ways to wire speakers to an amplifier, let’s take a closer look at how to wire 4 speakers to a 2 channel amp.

In fact, there are multiple ways to accomplish that. Each of which depends on factors such as your overall setup, what amp you have and how many ohms the speakers are, not to mention the way you want to do the wiring …etc.

So, let’s imagine you have a set of 6.5 speakers in the front doors, and set of 6X9 speakers running in the rear deck. All of which should be hooked up to a 4 ohm 2 channel amplifier that’s stable down to 1 ohm.

P.S: On a side note, the easiest way to wire all these speakers is to hook up the weakest of them (in terms of power handling) directly to the head unit, and wire the remaining ones to the amplifier – One channel per speaker.

 

4 Speakers Wired in Series:

  1. Step 1:
    Start by running a wire from the positive terminal on the amp to the positive terminal on the first speaker.
  2. Step 2:
    Then connect the negative terminal of the first speaker to the positive terminal of the second speaker.
  3. Step 3:
    Next, connect the negative terminal of the second speaker to the positive terminal of the third speaker.
  4. Step 4:
    After that, connect the negative terminal of the third speaker to the positive terminal of the last (fourth) speaker.
  5. Step 5:
    Finally, to close the loop, connect the negative terminal of the last speaker to your amplifier, and voila!

4 Speakers Wired In Series

4 Speakers Wired in Parallel:

  1. Step 1:
    Similarly to series wiring, you need to start by running a wire from the positive terminal on the amp to the positive terminal on the first speaker.
  2. Step 2:
    Then, you will need to run two wires between the first two speakers. The first wire will connect the two positive terminals, and the second wire will connect the two negative terminals (as shown in the diagram).
  3. Step 3:
    Next, repeat the same thing as in step 2 to the remaining two speakers.
  4. Step 4:
    Now that the first two speakers and the second two ones are wired in parallel, you need connect them. To do that, you’ll need run two wires between the first and last speaker. The first wire will connect the two positive terminals, and the second will connect the two negative terminals (as shown in the diagram).
  5. Step 5:
    Finally, you need to close the loop by connecting the positive and the negative wires to the amplifier.

4 Speakers Wired In Parallel

Bear in mind that if your speakers are wired in series and that one of them goes out, the others will go out as well due to the way they’re connected. In a parallel circuit, only the failed speaker will stop producing sound.

4 Speakers Wired in Series/Parallel

You can also wire 4 speakers in series and in parallel simultaneously as shown in the diagram below

4 Speakers wired in series and in parallel

Alex Brown

Hey There, my name is Alex Brown, I'm an LA-based sound engineer with over 10 years experience installing, troubleshooting, and repairing commercial, automotive, and household sound equipment. I've installed highly competitive car audio systems, and everything from navigation systems to full car stereo systems, remote starters, alarms and beyond. I enjoy creating solutions and simplifying everyday needs. I also love helping people get great sounding gear, thereby, saving the world from bad sound one customer at a time.

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