How to test an Amplifier?

how to test an amplifier ?

An Amplifier can improve your listening experience whether it is inside your car or with a home stereo system. Amplifiers increase the audio signal from input sources and lead to an excellent output from the speakers. However, what brings confusion is ‘How to test an Amplifier.’ Not many individuals are well-versed in such technical sound equipment, and that’s how they often end up with some or other trouble.

But to overcome any such possibilities, here we have a detailed guide explaining ‘How to test an Amplifier’?

But before getting into details, let’s quickly learn ‘What is an Amplifier?

In the simplest words, an Amplifier is an electronic device that increases the power of a signal. Commonly known as an amp, this device can increase the Voltage, power, and current of a signal altogether for a better sound experience. Amplifiers are wireless communicators that can be used at both professional and personal levels.

There are two types of Amplifiers: Weak Signal amplifiers and Power Amplifiers.

Testing an Amplifier- All that you need to know

For those who know, testing an Amplifier will always prove an easy task. However, for those who don’t, it can be tricky and confusing, sometimes even dangerous. Since it is an electric item, any wrong step will undoubtedly lead to damage, even ones that can’t be undone. Therefore, before you begin testing, always make sure you know the right method. If not, consider asking a technician to teach and perform the needful for you for that particular time.

Meanwhile, we, too, have a quick guide explaining the process of testing an Amplifier. Please have a look:

  1. Firstly, attach power and ground wires which should be red and black in color, respectively. Upon connecting, both the wires will have 12-volt electricity flowing in along with a strong ground which helps the Amplifier to work.
  2. Next, touch the Amplifier’s electricity wire with the car’s battery-positive post. Similarly, touch the ground wire with the car’s battery negative post. The Amplifier has a strong connection device when the load turns on.
  3. Further, consider linking the Amplifier with a mic. Followed by attaching RCA cables of the audio system or the speaker wires with the speakers in Jacks. Simultaneously, link the Amplifier to the Amplifier’s output voltage. You may now be able to hear clear sound coming out of the speaker. However, if the Amplifier is on but there’s no sound or vibration, the device is possibly damaged.
  4. Next, consider checking all the accessible fuses. Now use one fuse in the Amplifier, possibly the one installed in the amp chassis.
  5. Now, the Amplifier must switch on. However, if it doesn’t, especially when electricity and ground are properly connected, consider checking the fuse once again. There are some possibilities that the circuit is burned from the inside.
  6. However, if the Amplifier connection is all right, then consider checking whether the power wire has an inline fuse or not. The fuse should be round, in a black or transparent plastic shell with metals on both sides and a wire in the center. The short wire is present in two parts which helps the Amplifier to power on. If the fuse is weak or rusted, better repair it or get it changed.

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How to test an Amplifier using a Multimeter?

Testing an Amplifier using a Multimeter isn’t an easy but very professional way. Though before doing so, it is important to configure the Multimeter. The process isn’t complicated, and it involves finding out the right wires and sockets just to get started. For configuring the Multimeter:

  1. To begin with, get the black probe into the common socket. It should be labeled as COM. Here put the red wire into a socket with label A. You can also use the socket with the highest amperage.
  2. Next, turn the Multimeter’s central dial to the appropriate setting according to the socket.

Steps for testing an Amplifier using a Multimeter:

  1. Firstly, disconnect the speaker wires from the output terminals of the Amplifier. Simultaneously, disable or disconnect if there are any electronic crossovers connected directly with the output terminals of the Amplifier. This is a very crucial step that ensures that nothing will interfere while you test.
  2. Next, set the Multimeter to AC since it is originally powered by DC voltage. This alteration is important since setting to AC can help test the outputs. Ensuring that the Multimeter produces proper results sets AC voltage between a range of 10 to 100.

TIP: On a multimeter, the AC voltage is typically represented as VAC, so do not get confused.

  1. Further, consider placing multimeter probes on the amplifier output terminals. Make sure you place the negative multimeter probe on the negative terminal and the positive multimeter probe on the positive terminal.

NOTE: Connect positive and negative probes to the bridged output terminals in case the Amplifier is operated on Mono mode.

  1. Now apply a test frequency by inserting a CD. Or, for added ease, you can even play a tune from any input source presently nearby. Ensure that the tune is of appropriate frequency depending upon the types of speakers you are using.

NOTE: For the subwoofer, play a tune of 50Hz at “0dB”. Whereas for midrange or tweeter amplifiers, the tune you play should be of 1kHz at “0dB”.

  1. Next, it is time to evaluate the results. Since now you have tested the frequency and learned the reading your Multimeter produced, the further process is tricky.
  2. Here’s a quick calculative section; make sure you look keenly over it.
  3. Amplifiers produce watt output ranging between 50 to 200 watts.
  4. Here, all you need to do is convert your Voltage to watts and then make the comparison. And to do so, use the formula ‘E²/R.’ Here E represents Voltage, and R represents resistance.

Note: For finding resistance, look at the manual or the body of the Amplifier.

Here’s a rough example of the calculation:

Assume you are making use of subwoofers with 10 Ohm resistance and getting a voltage reading of 30. Now in the subwoofer, 10 Ohm resistance means a parallel 5 Ohm resistance load on the Amplifier.

So considering that here Watt equals (30*30)/5, which results in 180. Now the Amplifier’s recommended watt output should be close to 180 Watts. If yes, then the device is working fine. Though if not, then it needs professional interference.


That was all for the topic ‘How to test an Amplifier’? The process, though straightforward, can still confuse a lot of people. However, instead of following the wrong method, it is better to ask any professional for help.

At any moment when you feel confused, take your Amplifier to a store, and they will test it for a nominal fee.

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