How to Use a Resistor With a Speaker to Make a 4-Ohm Load

Take, for example, the scenario in which you want to pair a 4-ohm speaker with a 100W/channel home receiver with an 8-ohm minimum resistance. It is possible to raise the overall resistance (speaker load measured in Ohms) to the comfortable limit of 8 by connecting a 4-ohm resistor in series with the other resistors. As a result of connecting the speakers in series with a resistor, each speaker receives only half of the total power supplied.

In this article, I’ll demonstrate how to use resistors to adjust (or match) the impedances of your speakers (with excellent graphics to guide you through the process).

The disadvantages of changing the impedance of a speaker with resistors are as follows: Know what sort of resistors you’ll need to get started, what to do if you can’t find the exact resistors you’re looking for (there are some clever workarounds for this. Where can I get the appropriate resistors?

Using a resistor with a speaker to make a 4-ohm load

how to use a resistor with a speaker to make 4 ohm load

Using the incorrect voice is common for impedance to cause issues with a stereo or amplifier. To correctly match and adjust the impedance that an amp or stereo senses, resistors can be used with speaker matching capacitors.

Using a resistor to make a 4-ohm loadFunctionsEssential products
Where a higher impedance speaker is requiredTo obtain the required ohms valueCheck the Resistor from Amazon
Where a lower impedance speaker is requiredIt helps get a lower value8-ohm amplifier 4-ohm speaker
To achieve the required ohmsTo help locate the exact values of resistors 

1. In situations where a higher impedance speaker is required, a lower impedance speaker should be used.

Install a resistor in series with a speaker to raise the speaker’s impedance and obtain the ohms value required by the amplifier.

2. In situations where a lower impedance speaker is required, using a higher impedance speaker

By connecting two resistors in series, it is possible to use a greater impedance speaker in places where a lower value is required. Using an 8-0hm amplifier with a speaker crossover meant to work only with 4-ohms is a good illustration of this.

3. To achieve the ohms value you require, you can use as many resistors as necessary

Even if you cannot locate the exact values of the resistors you require, you can combine several resistor values to achieve the overall value you need. This is effective as long as they can handle the electricity flowing through them.

Ways to change speaker impedance with resistors

Ways to change speaker impedance with resistors
  • Use a speaker with a lower impedance than you would normally be able to with an amplifier or audio system.
  • Use of an impedance speaker with a greater impedance where a lower impedance speaker is required

The second scenario is much less common than the first. However, it is pretty useful when using speakers that have crossovers and in a few other circumstances that you may encounter. If you want to use a speaker with a higher impedance than that required by a stereo or amplifier, that is usually not an issue. As long as the speaker impedance is equal to or greater than the minimum Ohms rating of a stereo or amplifier, it will operate safely.

Using a resistor to increase the total speaker impedance

Using a resistor to increase the total speaker impedance

You can use series resistors to increase the total impedance that the stereo or amplifier perceives if you intend to utilize a speaker with a lower impedance. Using this method, you may safely prevent overheating and burning out the devices you are connecting to.

Here’s what you’ll need:

  • To raise the speaker impedance as required, link a resistor with the appropriate resistance (Ohms) value and with at least half the power rating of the stereo or amplifier’s power output rating. A power resistor with a value of 25W or higher would be appropriate for a stereo system producing 50W per channel.
  • Protect any open resistor leads with electrical tape to do not short to speaker wire or other metal components. Ensure that the speaker or resistor wire is completely covered and not exposed when working with them.

By connecting resistors in series, you may effectively double or triple the impedance of your speaker.

Decreasing total speaker impedance using a resistor

Decreasing total speaker impedance using a resistor

In addition to increasing speaker impedance when linked to an amplifier or receiver, you can also efficiently reduce speaker impedance when connected to an amplifier or receiver. Although this isn’t something you’ll come into very often, there are a few instances in which knowing how to do it comes in quite handy, such as:

  • Using speaker crossovers with varied impedances to match different speakers
  • A temporary solution is using additional speakers until you can obtain replacements for the originals.
  • Replacing outmoded speakers with the next best ones you can locate, but make sure they have the same impedance as the old ones.
  • Because you’ve taken advantage of reduced speakers, you’ve gotten an exceptional deal.

In this scenario, putting resistors in series can help reduce the overall speaker load seen.

To accomplish this, the procedure is much the same as joining resistors in series, with the primary difference being that you will wire it in parallel:

  • Calculate the value of the resistor you’ll need in Ohms (this is normally the same as the speaker’s resistance)
  • To use a resistor with a speaker wire and a speaker, connect the resistor to the output terminals of the speaker (you do not have to connect the resistor directly to the speaker if that is a problem). Connect the speaker wire to the battery terminals of the resistor.
  • Ensure that any exposed speaker wires or resistor leads are entirely covered and protected so that they do not cause a short-circuit to surrounding wiring or metal.


Speakers are not precisely the same as resistors. Their impedance varies depending on the sound frequency they are playing in different places due to capacitance and how the AC musical signal affects the voice coil.

As a result, adding a resistor can somewhat affect the sound, leading a speaker to behave differently across the entire spectrum of sound frequencies.

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