Popping a crackling in our speakers is sure to raise concerns regardless of what we’re listening to.
What causes speakers to pop and crackle and how do we fix it? Speaker popping and crackling is caused by interrupted electrical current (audio signals) or, in other words, a loose or dirty connection. To fix crackling and popping, troubleshoot the connective wires to find the problem area and secure the connection and/or replace the cable.
In this article, we’ll talk more about popping and crackling in speakers; the likely culprits, and how to fix the issues.
What Causes Speakers To Pop And Crackle?
The main cause of speaker popping and crackling is interrupted current.
Speakers are transducers that convert electrical energy (audio signals) into mechanical wave energy (sound waves). Audio signals are electrical signals with alternating current.
To learn more about audio, sound and speakers as transducers, check out the following My New Microphone articles:
• What Is The Difference Between Sound And Audio?
• How Do Speakers & Headphones Work As Transducers?
Any interruption to this AC signal will cause popping and crackling.
Why is that?
Let’s begin by stating that speakers are designed to move linearly according to the applied audio signal. As the AC signal passes through the driver, the driver moves inward and outward to produce smooth sound waves.
At the peak of the audio signal (maximum positive voltage in a particular cycle), the driver is pushed as far outward as it will be during that cycle. At the trough, or negative peal (maximum negative voltage in a particular cycle), the driver is pulled as far inward as it will be during the cycle.
Let’s have a look at a simple sine wave signal to illustrate this point:
This sine wave represents a single-frequency audio signal. The dotted line represents no voltage.
The maximum positive voltage (forward current flow) is shown at the peak while the maximum negative voltage (backward current flow) is shown at the trough.
It also represents the movement of a speaker tasked with converting the audio signal into sound.
When the signal is at its zero point (the dotted line), the speaker will be at resting position. This is because no voltage is applied to the speaker driver, even if only for an instant while the electrical current switches direction.
At the peak, the speaker is pushed as far out as it will be during the cycle. At the trough, the speaker is pulled as far in as it will be during the cycle.
As we can imagine, the sine wave causes smooth movement in the speaker and, therefore, a smooth sound with no crackling/popping.
Now let’s look at what happens when there is current interrupt in the same signal. The resulting waveform could look something like this:
In this case, the audio signal and resulting speaker driver movement is not smooth. For a brief moment, the current is interrupted, which produces a period of no voltage.
We can infer that, for a brief moment, the speaker will be told to remain at rest position and not produce any sound.
The pop is not from the silence of the speaker but from how the speaker is told to get to its rest position.
In the diagram above, we see that the audio signal current interruption happens just after the peak. At this point, the audio signal drops off instantaneously.
The speaker driver is, therefore, tasked with being at two physical locations at the same time. In this case, it should be pushed outward and at resting position simultaneously. This is impossible.
So rather than teleporting, the driver attempts to move as fast as it can between the two locations at the current interrupt. This results in a popping or clicking sound.
What happens if the current interruptions happen very often, as is the case with faulty lead wires? Let’s have a look in a diagram below:
In this case, there are two points in time in which the audio signal is interrupted.
As we can see, there are 4 instances where the speaker is told to be in two different locations simultaneously. As we’ve mentioned before, this causes pops and clicks.
Speaker popping in close succession like this leads to what we often refer to as “speaker crackle.”
A Note On Square Waves
Another basic audio waveform in audio synthesis is the square wave. As the name suggests, it looks something like this:
A perfect square wave would actually sound terrible played back through a speaker. There would be inherent crackle in the waveform due to its sharp adjustment from maximum positive to maximum negative voltage and vice versa that happens in every cycle.
But this is just a “perfect mathematical square wave”. In practice, the square wave actually resembles something like this:
There is a steep transition between the max and min voltages that allows the speakers to oscillate linearly without having to attempt the impossibility of being in two places at once.
What About Digital Pops/Clicks?
This is also what happens in digital pops/clicks. If a digital audio signal is cut off abruptly, the signal could instantly go from some amplitude to zero amplitude.
This sudden drop in the digital signal shows up as an interruption in current when the audio is passed through a digital-to-analog converter.
The analog signal, then, effectively tells the speaker driver that it needs to be in two places simultaneously. This causes the speaker to pop/click and is very distracting.
This is why crossfading is essential in digital audio editing.
What About Vinyl Crackle?
Oh the beloved crackle of vinyl records.
This crackle is not caused by the same interruption to current as the aforementioned audio pops and crackles.
Rather, the “crackle” of vinyl is simply noise in the audio signal. The bulk of this noise is caused by static electricity and dust.
Vinyl naturally holds on to a decent amount of static electricity. Some of this static electricity is picked up as noise by the needle cartridge before it is amplified and sent to the speakers.
The bigger culprit, though, is dust and debris that finds itself in the grooves of the record. This dirt is largely attracted by the static charge of the vinyl.
To mitigate the “vinyl crackle,” I recommend investing in an anti-static vinyl brush and using it before every listening session.
AudioQuest has an excellent anti-static vinyl brush. Click here to compare its price on Amazon and other retailers.
How To Fix Popping & Crackling In Speakers
We’ve mentioned crossfading during digital audio editing and keeping your vinyl records clean but how do we stop a speaker from popping and crackling from true current interrupt?
Fix the cables!
This could be as simple as repairing or replacing an auxiliary 3.5mm TRS cable in your car or as complex as disassembling an amplifier to troubleshoot.
That being said, the issue of current interruption between the audio source and the speaker driver is nearly always linked to a loose or otherwise faulty cable and/or connection.
We can troubleshoot these issues by going along the cable to see if there are any loose connections. Wiggle the wires while playing audio at a quiet volume to find where the loose cable/connection is.
The fix could require the re-soldering of connections in the speaker, amplifier or audio source. It could also include repairing a wire or replacing a cable completely.
The trick is to troubleshoot before going ahead with any fixes.
Why do my speakers distort at high volume? Speakers distort at high volumes for two main reasons. The most common is that the audio source, itself, is distorted. However, speakers can also distort if their drivers are pushed to the extremes of their designed motion, in which case they behave non-linearly and produce distorted sound.
To learn more about why speakers distort at high volumes, check out my article Why Do Speakers Distort At High Sound/Audio Levels?
How do you fix a blown speaker? To fix blown speakers requires the replacement of one or more parts. A blown-out speaker typically has a burned or melted voice coil, which would need replacing and rewiring. Alternatively, a blown-out speaker could need its cone and/or housing replaced.