How To Wire A 4 Channel Amp To 4 Speakers And A Sub

how to wire a 4 channel amp to 4 speakers and a sub

A 4-channel amplifier gives an excellent audio output for your guitar, but it is restricted to be used with either of the two – speakers or sub. However, when you use both speakers and a sub together, the audio quality is enhanced exceptionally. To overcome the restriction, we need to get a bit innovative with the wiring and if you get it right, you need to know how to wire a 4 channel amp to 4 speakers and a sub.

If you have a 4 channel amp, it's great for you to have great flexibility. They are meant to use with 4 speakers or 2 speakers and a sub. You cannot use both. You can wire a 4 channel amp to 4 speakers and a sub. It's possible to do this inexpensively. Before moving on, it is important to make one thing clear that you will have to make compromises to drive 4 speakers and a sub with a single 4-channel amp.

You may end up giving front-rear fader control ability as you will not be able to use 2 channels for the rear speakers to drive a sub. Today most of the car cannot handle speaker loads up to ohms. Using 4 speakers from 2 channels which means that speakers are using the amp's power, so there will be less power for both.

Today most car amps have a minimum of 2 ohms per channel in standard and 4 ohms minimum when bridged. Make sure that, you never run an amplifier with a speaker load lower than the rating. There might be a chance that your amp will become hot or it can be damaged.






Wiring of the amp

Here we are covering three combinations of speakers and amps, and this can would cover almost all types of systems out there 

These are some amp wiring systems:

  • 4 channel amps with a minimum speaker load of 2 ohms in stereo, 4 ohms bridged (for the subwoofer).
  • 4 channel amps with a minimum speaker load of 2 ohms in either stereo or bridged.
  • 4 channel amps with a minimum speaker load of 4 ohms.

Few examples 4 channel amp wiring:

  • In system 1, you can do parallel wiring with 2 speakers to each channel. 2 Ohms x 2 + 1 subwoofer wired for 4 Ohms.
  • For system 2(Parallel), 2 Ohms x 2 + 1 subwoofer wired for 4 Ohms or 2 Ohms. For more power, you can wire this on the rear channels bridged.
  • System 3(parallel wiring), connect 2 speakers on each front channel with additional parts for 4 ohms per channel + 1 subwoofer wired for 4 ohms minimum.

The Key Measurements

We may find that Car stereo and home speakers are quite similar except for the impedance rating. Speaker's impedance value is measured in Ohms. Due to several other reasons, car stereos are usually rated at 4 ohms. Home stereos are usually rated around 8 Ohms.

The only thing you want to know is what is the resistance of a speaker. If you can manage to measure that, you will automatically get to know what Ohms rating you will be required. In most cases, speakers come with a label whether it is 2 ohms, 4 ohms, or with more voltage. 


But, some speakers don't come with a label. Therefore, if you have a multimeter, you can find out with a hundred percent result.  Make sure that when you are measuring, other substances are not interfering with the measurement.

Following are the things that can cause problems:

  • If there is a leftover solder flux or solder coating.
  • Due to oxidation.
  • Dirt and dust or any other contaminants.
  • Paint or coatings that are poor conductor of electricity.

Usually, Car and home speakers are rated by general Ohms rating. Speakers with 2, 4, 8 Ohms are never measured correctly with Ohm measurements. It happens because each speaker's design is different from the next. The resistance you measure from a speaker is because of the voice coil's resistance.

Rating Measurements:

  • 2 Ohms - 1 -1.8 Ohms
  • 4 Ohms - 3.2 - 3.6 Ohms
  • 8 Ohms - 6 Ohms or more
  • 16 Ohms - 12 Ohms or more
Note:  You are interested in making thinks for scrap then check how to make a guitar amp from a speaker article to build a custom guitar amp for your needs.

How to wire a four-channel amp to 4 speakers and a sub

bridging an amp

Bridged Mode is a built-in amplifier feature. It has a "push-pull" setup. One channel is used for the left speaker that produces a signal that is the opposite of the second channel that is used for the right speaker. By using Bridged mode, you will get more power from 2 channels. Subwoofers require more power because they are heavy and big speakers. They require more power to produce the bass than smaller speakers.

wiring methods

Most commonly, speakers are 4 ohms. Remember to check all speakers before wiring them to the amp to all is compatible to use.

  • Method 1: Use a 4 channel amp with 2 Ohms stereo, 4 Ohms bridged.
    Every front amp is connected with 2 speakers in a parallel series for 2 Ohms per channel.
  • Method 2: Use a 4 channel amp with 2 Ohms stereo, 2 Ohms bridged.
  • Method 3: Use a 4 channel with 4 Ohms with minimum speaker load.
how to wire a 4 channel amp to 4 speakers and a sub

With the help of power resistors, you can keep the total speaker safe, and amp won't get damaged. Resistors are very easy to use, and they can be easily bought.

When it comes to car amplifiers, they can't go below 4 ohms per channel. But, you can add one 4 Ohm power resistor in series. By doing this you will have two 8 Ohms in parallel which will give you safe 4 Ohms per channel. The right kind of resistor for this will be 25 watts (25W) 4-ohm resistors. .

Though they are affordable, you will not find this resistor in any local store. They can be used if you face any speaker-related issues. Power resistors are designed to handle a large amount of heat.


With the help of the above-mentioned steps, you can wire a 4-channel Amp to speakers and a subwoofer. Just make sure you take care of the technical specifications and follow the steps correctly to avoid any complications in the setting up and functioning of your audio system.

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