How To Match Amplifiers And Speakers

Norvan Martin
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Like peanut butter and jelly, speakers, and amps should complement each other. Otherwise, the audio output won’t be as good as it could be and in extreme circumstances, you may end up damaging your amp! However, matching speakers and amplifiers can be tricky, especially if you don’t plan to buy a packaged system; but instead have a separate amplifier and speaker. Knowing what to look for can be difficult.

This article will show you how to match loudspeakers and amplifiers without damaging your expensive equipment. 

Important Terms That You Should Know

The key to ensuring effective speaker-amplifier synergy is a basic understanding of the fundamental terms used in speaker and amplifier specifications, which is essential in your quest for incredible, long-lasting sound. These terms are; Sensitivity, Power, and Impedance.


Speaker impedance is one of the most important factors to consider. All speakers typically have an impedance or resistance between 4 and 8 ohms. Determining the impedance of your speakers is an important step and you can do this by consulting your speaker manual or the manufacturer’s website.


Of course, depending on how your speakers are connected (in series or parallel) and the number of speakers, this will affect the overall impedance of the speakers from the amplifier’s perspective.

Typically, amplifiers work best and are rated within a certain range, e.g. between 4 and 12 ohms. You can determine if your amplifier and speakers are compatible by looking at their specifications and determining if the amplifier can handle the impedance of the speakers.

You should not connect speakers with a lower impedance (e.g. 2 ohms) to an amplifier with a higher minimum impedance (4 ohms). This is because, the lower the impedance, the more current or power the speakers will demand.

If the amplifier cannot deliver this power output, it will exceed its limits and may blow. It is however acceptable to connect speakers with a higher impedance to an amplifier that can operate at a lower impedance. 


This only applies to speakers. Speaker sensitivity or speaker SPL (Sound Pressure Level) is efficiency. It is a measure of how effectively a loudspeaker converts electrical power into sound output. Sensitivity is measured by looking at how loud a speaker is in decibels when placed one meter away and powered at one watt. This is directly related to the maximum speaker volume.

speaker sensitivity

Assuming both speakers are driven with the same input power, in the same room and setup, a speaker with a lower sensitivity (e.g. 80dB) would sound quieter than a speaker with a higher sensitivity (e.g. 85dB).

While sensitivity doesn’t determine whether a speaker is good or bad, a speaker with higher sensitivity can save you from buying a larger amplifier to achieve your preferred listening volume.


Watts are used to measure the power of audio equipment like any other electrical component. This often leads buyers to mistakenly believe that more power means more volume.

This is not always the case. The power of your speakers and amplifier will determine how much power the speaker can handle and how much power the amplifier will put out.

Amplifier specifications are often referred to as continuous power (sometimes referred to as continuous output power or continuous RMS power) and dynamic power (sometimes referred to as peak power). 

Continuous power or RMS delivers constant power into a fixed number of ohms, e.g. B. 50 watts per channel at 4 and 8 ohms. However, Dynamic Power can transfer 100 watts into 8 ohms and 150 watts into 4 ohms.

Note the continuous power and output power of your amplifier, then compare these numbers to the suggested speaker gain settings. You can judge the compatibility by comparing these two numbers. 


Amplifier Speaker Matching Calculator

Below is a simple speaker and amplifier matching calculator. Use it to determine if your speakers and amplifier match.

Amplifier Speaker Matching Calculator


Connection Type

To have a compatible speaker and amplifier, select an amplifier that can deliver roughly twice the speaker’s continuous power rating.

Keep in mind that doubling the wattage only results in a three-decibel change. This will enable the amplifier to deliver sufficient power to the speaker while preserving some extra headroom to prevent the amplifier’s tendency to overdrive the input.

The easiest method to avoid damage and get the best sound quality is to use speakers that are made to deliver the right amount of sound pressure for the task at hand. This will prevent you from accidentally turning the speakers up past their safe volume level.

Amplifier Speaker Wattage Calculator

It is important to find out what voltage the amplifier works at. Voltage information is frequently displayed on the bottom or back of audio equipment. If not, refer to the user guide that was included with the gadget.


Find out how much recommended current the device’s wiring can handle. This information ought to be included in any documentation that you discovered useful in the earlier stage.

Matching Amplifier To Speakers Wattage

Note Ohm’s Law for power:

P = V * I

where P is power, V is voltage and I is current.

Plug in your determined values for V and I, then solve for P. 

This value is the wattage of your amplifier.

NOTE: The Speaker does not produce power: this is an amplifier’s job. An amplifier’s wattage must fall within the acceptable wattage range for a speaker. 

Car Amplifier Speaker Wattage Calculator

You can use the calculator below to determine your required speaker wattage:

Car Amplifier Speaker Wattage Calculator

To determine the watts on the car amplifier, you need a multimeter, subwoofer, clamp meter, screwdriver, an amplifier, and a source like a smartphone or MP3 player. 

The amplifier’s AC voltage rating will be determined with a multimeter, whilst the car’s amplifier’s output amperage will be determined using a clamp meter. The output power will be tested using the subwoofer, and the entire process can only be completed if we have a car amplifier.

The last one is an MP3 player that will be used to test the amplifier by playing a test sound. To get the wattage of your car amplifier, follow the steps chronologically;

  1. Connect the subwoofer to the amplifier
  2. Connect the multimeter to the amplifier
  3. Clamp the clamp meter with the wire of the subwoofer
  4. Play a bass test sound with an mp3 player
  5. Measure the wattage
  6. Increase the output volume and measure it again
  7. Calculate the maximum wattage

Using an Overpowered or Underpowered Amplifier

It is possible to go beyond the speaker’s capabilities by selecting an amplifier that can output too much power. This causes distortion which can eventually get the speaker spoilt.

On the other hand, choosing an amp that isn’t powerful enough to adequately power the speaker increases the risk of damage. The amp won’t have enough power to operate the speaker at its best volume if it is underpowered.


It can be a technical nightmare if you’re buying an amplifier and speakers separately. The topic of matching amplifiers and speakers might be confusing. However, when you break it down to the essential things, you can see that there isn’t too much to worry about when matching speakers and amplifiers.

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Norvan Martin is the founder of He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics. My email: [email protected]  Connect on Pinterest and Linkedin