Testing an amplifier’s output is a crucial step in ensuring that it is functioning properly. By using a multimeter, you can measure the voltage and current output of the amplifier and make sure that it meets the specifications outlined by the manufacturer. In this article, we will answer some common questions about how to test an amplifier’s output and provide some useful tips for doing so. Let’s get started!
Amplifiers in General
It is a basic building block in many electronic circuits, and its function is to make weak signals stronger so that they can be processed by other devices downstream.
There are two types of amplifiers: voltage amplifiers and current amplifiers. As their names suggest, voltage amplifiers increase the voltage of a signal while current amplifiers increase the current.
Most amplifiers have three terminals: input, output, and ground. The input terminal is where the signal enters the amplifier, and the output terminal is where the amplified signal exits. The ground terminal provides a reference point against which the voltages of the other two terminals are measured.
Amplifiers are used in a wide variety of electronic devices, from radios and TVs to computers and cell phones. In fact, just about any device that uses an electronic signal will have at least one amplifier somewhere in its circuitry.
One of the most common places you’ll find amplifiers is in audio equipment. Amplifiers are used to increase the volume of sound coming from loudspeakers. They can also be used to improve the quality of the sound by equalizing or filtering the signal.
In addition to audio applications, amplifiers are also used in many other types of electronics such as:
- Automotive systems
- Medical equipment
- Home theater systems
- Wireless communications
As you can see, amplifiers play a vital role in many different types of electronic devices. They are an essential piece of equipment for anyone working with electronics. [1], [2], [3]
What is a Multimeter?
It can also be used to test continuity and diodes. A multimeter is an essential tool for any electronics enthusiast or technician.
There are two types of multimeters: digital and analog. Digital multimeters are more common and easier to use than analog ones. They usually have a large LCD display that shows the reading in digits. Analog multimeters have a needle that swings back and forth to indicate the readings on a dial.
Digital multimeters usually have more features than analog ones. For example, they may include a built-in temperature sensor or capacitance measurement functions. However, analog multimeters are often preferred for their simplicity and ruggedness.
Most multimeters can measure DC voltage, AC voltage, DC current, and AC current. Some also have the ability to measure resistance, continuity, and diodes. [4]
Testing an Amplifier Output With a Multimeter
The output power of your amplifier is one of the most important performance metrics. It tells you how much power the amplifier can deliver to its load, and it is a key factor in determining the overall loudness of your system. There are a few different reasons why you might want to measure the output power of your amplifier:
- To make sure that the amplifier is working properly
- To compare the output power of different amplifiers
- To determine how much headroom the amplifier has
- To find out if the amplifier is clipping
Now that you know what an amplifier is and what it does, let’s take a look at how to test one with a multimeter. The process isn’t as hard as it might seem, and with a little practice, you’ll be able to do it like a pro.
Locate the amplifier
The first step is to locate the amplifier. In most cases, the amplifier will be located near the speakers. If you’re not sure where to find it, consult your vehicle’s/device’s owner’s manual. Once you’ve found the amplifier, you’ll need to identify the three terminals: input, output, and ground. We have slightly covered those already, but let’s review their main purposes again.
The input terminal of the amplifier is where you will connect your audio source. This can be either an external device such as a CD player or turntable, or it can be the output from your computer’s sound card.
The output terminal of an amplifier is where you will connect your speakers. This is where the amplified signal exits. The ground terminal provides a reference point against which the voltages of the other two terminals are measured. [2], [3], [5]
Double check the plugs and wiring diagram
Now that you’ve located the amplifier, it’s time to take a look at the plugs and wiring diagram. This will help you determine which multimeter setting to use and how to hook up the leads. If everything is in order, you’re ready to move on to the next step. [2], [5]
Disconnect the speakers
The next step is to disconnect the speakers from the amplifier. This is an obvious step to make, since you will be testing the output of the amplifier and you don’t want the speakers to be part of that equation. Once the speakers are disconnected, you can proceed to the next step.
If your amplifier has more than one set of speaker outputs, make sure to disconnect all of them before proceeding.
It’s also a good idea to disconnect any other devices that might be connected to the amplifier, such as a CD player or turntable. This will help prevent any interference from those devices during the testing process. [2], [5]
With the Signal Generator OFF
Now that the speakers are disconnected, it’s time to test the amplifier output. But before you do, there’s one more thing you need to do: turn off the signal generator.
The signal generator is what provides the input signal to the amplifier. If it’s on, it will interfere with the testing process, so make sure it’s turned off before you proceed. [5]
Disable any electronic crossovers
If your amplifier has an electronic crossover, you’ll need to disable it before proceeding. This can usually be done by setting the crossover switch to the “off” position or by disconnecting the power wire from the crossover.
Doing this will ensure that you get an accurate reading from your multimeter. If you don’t disable the electronic crossover, you may end up with a false reading. [5]
Set the multimeter to AC voltage
Now it’s time to set your multimeter to AC voltage. You’ll need to consult your multimeter’s user manual to determine how to do this. Once the multimeter is set, you can proceed to the next step. If you’re not sure how to set the multimeter, don’t hesitate to ask a friend or family member for help.
We also suggest setting the range to 10 – 100 volts. This will give you a good range to work with and will help prevent damage to your multimeter if there is a sudden spike in voltage. [2], [5]
Probe the output terminals
Now it’s time to probe the output terminals of the amplifier. To do this, you’ll need to touch the positive (red) lead of the multimeter to the positive output terminal and the negative (black) lead of the multimeter to the negative output terminal. Once you’ve done that, you can take a look at the reading on the multimeter.
In case your amplifier operates in bridge mode, you will need to touch the leads to the bridged terminals. [2], [5]
Apply a test frequency
Now that you have the multimeter hooked up, it’s time to apply a test frequency. You can start with a low frequency and then work your way up. This will help you get a feel for how the amplifier is performing and will allow you to make any necessary adjustments. We suggest you use the frequency you normally listen to music at.
Turn the signal generator back ON and slowly increase the frequency until you reach the desired level.
If you use subwoofers, you will want to set a frequency of at least 50Hz. And if you are using tweeters or full-range speakers, we recommend a frequency of around 1000Hz. [2], [5]
Check the readings on the multimeter
As you increase the frequency, you should see the readings on the multimeter change. These changes will tell you how well the amplifier is performing. Check the readings to see if they match the specifications of the amplifier. If they don’t, then you may need to make some adjustments.
If you see a sudden spike in voltage, it’s possible that the amplifier is clipping. This is an indication that the amplifier is being pushed too hard and is starting to distort the signal. If you see this, we recommend backing off on the volume or frequency until the distortion goes away.
Now it’s time for some math. To get the amplifier’s actual output voltage, you’ll need to convert the voltage reading on the multimeter to watts. To do this, you’ll need to use the following equation:
- E²/R
where:
- E is the voltage reading on the multimeter
- R is the amplifier’s resistance (measured in ohms)
You can use this equation to calculate the power output of your amplifier at any given frequency. Just make sure to plug in the correct values for each variable.
If this calculation produces a result that is different from the amplifier’s specified power output, then there may be something wrong with the amplifier. We recommend taking it to a professional for further diagnosis. [2], [5]
FAQ
How do you know if your amp is fried?
If you have an oscilloscope, you can measure the AC voltage at the amplifier output. If it is zero, or very close to zero, then the amplifier is probably fried.
How do you test amp power output?
One way to test amplifier power output is by using a multimeter. To do this, set the multimeter to read AC volts and connect the positive lead to the amp’s positive terminal and the negative lead to the amp’s negative terminal. The reading on the multimeter will tell you how much voltage is being sent through the amplifier.
Can you check a speaker output with a multimeter?
Yes, you can check a speaker output with a multimeter. By setting the multimeter to the resistance measurement mode, you can measure the A resistance of the speaker coil. This will tell you if the speaker is working or not.
What’s more, you can also measure the power output of your amplifier by using a multimeter. To do this, set the multimeter to AC volts mode and measure the voltage between the positive and negative terminals of your amplifier. Keep in mind that you should always disconnect your speakers before measuring the amplifier’s output.
How do you know when an amplifier is blown out?
You can tell if an amplifier is blown out by the sound it makes. If you notice that your amplifier is making a distorted, crackling, or popping sound, then it is likely that the amplifier is blown out.
Another way to tell if an amplifier is blown out is by looking at the fuse. If the fuse has been blown, then this means that too much current was flowing through the amplifier and caused the fuse to blow. This usually happens when there is a short circuit somewhere in the amplifier circuitry.
Useful Video: Amplifier Cutting Out? Protect Mode? No Sound? Test these!
Conclusion
Testing your amplifier output with a multimeter is not difficult, but it does require some basic understanding of how electricity works. By following the steps outlined in this guide, you should be able to get accurate readings from your amplifier and make sure that it is functioning properly. As long as the end readings match the recommended watt output for your amplifier, you can be confident that it is working as it should.
Now that you know how to test an amplifier output with a multimeter, you can use this information to troubleshoot any problems you may be having with your audio system. Just remember to follow all safety precautions and to consult your user manual before making any changes. With a little bit of patience and attention to detail, you should be able to get your audio system sounding great in no time!
References
- https://www.watelectronics.com/different-types-of-amplifiers/
- https://electrouniversity.com/how-to-test-amplifier-output-with-multimeter/
- https://www.foraudiogeeks.com/how-to-test-a-car-amplifier/
- https://www.fluke.com/en-us/learn/blog/electrical/what-is-a-digital-multimeter
- https://rftech.custhelp.com/app/answers/detail/a_id/468/~/measuring-amplifier-output-power
