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6 Steps On How To Test Amplifier Output With Multimeter

Trying to find out how to test amplifier output with multimeter can be a daunting task. Especially if you never did it before.

However, having the right tools can save you a lot of hassle, time, and money. It’s actually a pretty straightforward operation, especially if you have all the necessary tools at hand.

There are, however, a few essential key factors you need to know before you you get started.

So, how to test amplifier output with multimeter?

When is the right time to through in your towel and call a professional instead? We have the answer to your questions, so sit tight while we teach you how to test your amplifier output using a multimeter.

What is a multimeter, and what does it do?

Multimeters or multitesters are electronic devices used to measure several key components of an electrical circuit. It is an important item in any professional electrician’s toolbox as well as in a hobbyist’s arsenal.

Multimeters can be bought from any electronic store.
A multimeter measures voltage, currents, and resistance. It’s also instrumental in determining whether or not there’s a problem with your amplifier.

Here is a shortlist of common issues to look out for.

· The amplifier output is distorted.

· The amplifier doesn’t switch on.

· The amplifier switches on but has zero output.

· The amplifier switches on and off by itself.

· The amplifier enables safety or protection mode.

Things you need to test the output of the amplifier

There are three main features that you need when testing an amplifier’s output.

1. A multimeter.

2. An amplifier.

3. Some or a lot of patience depending on what device you are trying to test.

If you have a simple speaker setup or other devices you want to test, it’s pretty straightforward, but if you happen to have a large setup with at least eight speakers, then you better be well-rested and have a lot of patience in store.

Although doable, the whole process is quite time-consuming since you probably need to test each unit to find any faults. If the central unit lights up and works properly, the issue may very well be tied to any external amps.

Configuring the Multimeter

Step 1

Start by checking the nameplate of the component or device you want to test to determine its highest amp output. Before connecting the multimeter to the electrical circuit, ensure that the multimeter is rated high enough for the amps to travel through the circuit.

Almost all power sources have the estimated max amperage printed on the nameplate. You can see how many amps a multimeter can operate on the back of the gadget or in the manual.

Another way to determine what the multimeter is capable of is by checking what settings the central dial has. Do not try to test any devices with a higher current than the multimeter can handle.

Step 2

If the multimeter has a lower rating than the circuit, you should use a plug-in clamp. The plug-in clamp can increase the amp range of the multimeter. Simply attach the leads to the meter and connect the opposite ends to the electrical circuit.

It should be done the same way as you would connect the clamps to the multimeter. Position the clamp on the live or hot wire, usually black, blue, or red. It can sometimes be another color except green or white.

If you are using a clamp, note that it won’t become a part of the electrical circuit, contrary to when you only use a multimeter.

Step 3

No matter if you’re using a clamp attachment or not, the multimeter should have a black and a red probe. The multimeter has a socket labeled COM.

This is where you should insert the black probe. One end of the probe is equipped with a prong and is the end that should be inserted into the multimeter. COM is short for common, and if the socket isn’t labeled COM, there will be a negative sign instead.

If the leads are equipped with prongs, you’ll have to manually hold them in position while measuring the current. If the probe has a clamp, you can connect it directly to the electrical circuit, which will free up both your hands.

However, no matter which type of probe you use, they connect the same way to the multimeter.

Step 4

Insert the red probe in the amperage or A labeled socket. Your multimeter might have several sockets where the red probe can be inserted, but that depends on the meter and its features.

Some multimeters even have two sockets labeled A. One port is labeled A or 10A and is designed for currents up to 10 amps. The other is labeled mA, which measures milli-amps. They usually measure up to around 300 milli-amps.

If you are unsure which port to use, use the A or 10A port to make sure the multimeter doesn’t overload

Step 5

Unless your multimeter is designed exclusively for AC or DC circuits, you need to choose which electrical circuit you are testing. If you’re uncertain, you can read the nameplate on the power source. The circuit should have that information as well as the voltage.

Alternating current or AC is often used for electric motors and household appliances, while direct connection or DC is often used for engines and devices driven by batteries.

A residential environment uses AC power unless you have a transformer that converts the electricity into DC.

Step 6

Once you have established the maximum currents you want to test, use the central dial on the multimeter to turn the amperage setting to match the socket. For example, if the circuit is estimated to be 5 amps, instead of setting the dial to five amps, you should set it to 10 amps.

You can even set it to the max if you want to be on the safe side since a lower amp setting can overload the multimeter and not give you a reading. Should that happen, you have to reset the dial and do it once more.

Setting your multimeter to a higher level than expected also protects against accidentally blowing any fuses should the current be more substantial than expected. If the current is notably higher than the amperage setting, the multimeter could be destroyed.

A few dials use auto-ranging, meaning you don’t have to adjust the dial manually. If your multimeter is one of them, you won’t see a dial that has amperage settings, and the multimeter will be tagged as auto-ranging, or the display will read AUTO.

Testing-How to test amplifier output with multimeter

Since each manufacturer designs their amps a little differently from each other, you need to check the manual! There should be a wiring diagram that tells you which wires are used for testing, along with the characteristics you should expect if the amp is working.

Step 1

You need to turn the circuit’s power off. If the circuit is battery-powered, disconnect the negative lead that runs from that battery; if the device has a breaker, use the switch to turn off the power and disengage the negative lead. Don’t attach the multimeter with the circuit’s power on.

You have to be cautious when dealing with electricity. Wear thick rubber gloves or other protective gear.

Don’t work on metal surfaces or near water. And never touch unprotected wires with your bare hands.

Try to have a friend or family member nearby to help you or call emergency assistance if you get electrified.

Step 2

Unplug the red cable that is attached to the power supply. To test how much current flows through an electrical circuit, you need to connect the multimeter, completing the circuit.

Start by turning the power off, then disconnect the positive cable, which is red most of the time, from the power source, which is called “breaking the circuit.” In some cases, you might need to cut the cable with clippers to make the circuit break.

If a cap is present where the device’s cable meets the cable coming from the power source, disconnect the cap and separate the wires from one another. The cables can also be attached by clips that can be detached.

You don’t have to disconnect the black wire since it is negative in a DC circuit, while in AC circuits, it’s the live wire.

Step 3

If needed, strip the rubber from the wire’s ends. Twist a small part of the wire around the prongs on the multimeter, or expose enough wire so the alligator prongs can securely be clamped on.

Should the wire have insulated rubber all the way, cut the wire insulation about 2.5 cm from the end. To do this, take your wire clippers and press them until you cut the insulation rubber.

Then pull the clippers away from you, removing the insulation. Should you, by mistake, cut into the wire, cut off that section, and do it again. The end that’s not connected to the power source needs to be stripped. Same with the wire that comes from the unit you are testing.

Step 4

Grab the end of the red wire that you just stripped, twist it around the multimeters probe, or fasten the clips to the wire depending on what probe you are using. No matter what, you need to ensure that the wire is securely attached to get a precise reading.

Technically, it won’t make a difference if the positive probe is attached to the wire coming from the device or the power source. The circuit just needs to be completed by the multimeter. If you find it easier to attach the wires the other way around, that’s fine.

Connect the positive wire first; this helps prevent a shortage if the negative wire should touch the ground. If you’re not using the amperage clamp while measuring the circuit and your reading shows a negative number, it means the leads are put on backward. So, you’ll need to reverse them to fix it.

Step 5

Next, you need to locate the positive wire from the electrical device you’re testing and connect it to the black probe on the multimeter. If you cut the circuit by unhooking the cables on a battery-powered device, power will automatically be restored once you connect the black probe to the cable.

If you used a switch or a breaker, you need to turn the power back on.

If you are testing amplifiers in a car. Don’t ignite the vehicle, and do not turn on any lights, fans, or anything else, as the multimeter could become overloaded.

Step 6

Once the multimeter is connected, you should immediately see a reading on the display, which is the amp or current measurement. Even though this preliminary reading can be accurate, to get an even more precise reading,

let the probes stay connected for at least one minute to ensure that the current is stable.

If your reading is lower than the acute amperage setting, it might read lower than 0.3 A. If this happens and the sensitive setting on your multimeter can handle up to 300 mA, unhook the multimeter and insert the red probe in the mA port and test again.

Always keep your selected current range in consideration while reading the number. If you chose ten amps, it might only show 0.01 amps on one setting while indicating a 10 amp reading on another if the multimeter is set to a higher milliamp radius.


Although the process of testing the output of an amplifier with a multimeter is pretty straightforward, it’s incredibly time-consuming, especially if you are testing a large speaker setup. This guide was put together to help you configure the multimeter and teach you how to test your devices.

And if you follow it step-by-step, you will soon learn to master the process, even if you’ve never done it before.

You must be extremely careful when handling electricity and always try to have someone nearby. Multimeters come in many varieties, from auto-range to manual settings.

If you don’t already have a multimeter, you can pick one up from any electrical store. You also need to be patient when testing the amplifier’s output, no matter the device.

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