Humming, hissing, buzzing and noise in general can quickly ruin our audio experience with speakers. Knowing the causes of and solutions to our speaker noise issues can save us a lot of grief and frustration when it comes to getting the best results out of our audio equipment.
What causes speaker hum/buzz and hiss and how do we eliminate this noise? Though some noise is inherent in the audio signal (tape hiss, amp gain, etc.), speaker hum and hiss generally come from poor wiring, ground loops or other electromagnetic interferences (AC line hum; RF interference, and USB and PC noise). To rid of the noise, we must rid of the interference.
In this article, we’ll go through each of the common causes of speaker hum and hiss and discuss the effective strategies we can implement to rid of the noise in our speakers and audio systems.
What Is Speaker Hum And Hiss?
As the names suggest, speaker hum and hiss refer to any audible hum and hiss we hear from our speakers. This noise can be very irritating and troublesome to get rid of.
Let’s list out the reasons for speaker hum and hiss to get a better understanding:
- Inherent hum/hiss in the audio signal
- Analog audio equipment
- Amplifier gain (including mic/line/speaker level mismatching)
- Poor wiring
- Ground loop
- AC line hum
- Radio frequency interference
- Computer noise
- USB noise
- Transformer noise (lamination rattle)
- Blown speakers
Let’s define each of these noise-inducing issues in greater detail along with how to troubleshoot and fix the problems to eliminate speaker hum and hiss.
Inherent Noise In The Audio Signal
Sometimes there is hiss and hum printed into the audio signal itself. Speakers are meant to reproduce audio signals and so any noise in the audio will often come out of the speaker as hiss and hum.
Solution To Noise In The Audio Signal
There’s not really an easy solution to remove inherent audio signal from a speaker other than removing the noise from the audio.
If you’re recording the audio, try to eliminate noise at the source and in the mix.
For more information on reducing noise at the recording source, check out my article titled 15 Ways To Effectively Reduce Microphone Noise.
Try finding a higher quality audio file of what you’d like to be listening to.
Noise From Analog Equipment
Analog equipment (like analog tape and vinyl and the playback systems that read audio from them) will often produce hiss and hum that will be translated to the speakers.
Though analog recordings are often cherished for their warmth and character, the inherent noise may be an issue when listening back at high volumes.
Solution To Noise From Analog Equipment
Try cleaning and/or upgrading the analog playback equipment.
Another strategy is to go digital, though digital-to-analog converters (which are required if we are to drive speakers with digital audio) may also introduce noise to the signal.
Noise From Amplifier Gain
Amplifiers will often add noise to the audio signal. This is particularly true of low-end amplifiers and preamplifiers.
To test this, turn up the amplifier or the volume of your speakers without sending any audio signal to them. You’ll likely notice that the speakers produce more hiss without any audio.
This is the amplifier at work. Any time we apply gain to a signal, we also amplify the inherent noise of that signal.
Additionally, the electronic components in audio amplifiers will add their own noise to the signal. In many high-end amps, this is no big deal. With lower-end models, this extra noise can be distracting, especially as the amp is turned up.
Solution To Noise From Amplifier Gain
To mitigate speaker noise due to amplifier gain, try setting the gain stages correctly and match the speaker(s) to an appropriate amplifier.
Oftentimes the amplifier is built into the speakers and is the only gain stage between the audio device and the speaker. In this case, turning the volume down is a good idea.
Let’s quickly discuss setting up a public address (PA) system or other audio systems that utilizes mic, instrument, line and speaker level signals. Ensuring that the various signal strengths (and impedances) are connected to inputs/outputs designed to handle their voltages/impedances. Failing to do so can lead to significant noise and distortion.
Hum & Hiss From Poor Wiring
Poor wirings and connections can lead to speaker noise and even speaker blow-out.
Crackling and popping are common side effects of poor wiring in a speaker. To learn more about this particular type of noise, check out my article What Causes Speakers To Pop And Crackle, And How To Fix It.
Audio signals are AC electrical signals and they are carried via conductive wires. When jacks/plugs are connected, the electrical signal can pass from one component to another.
To learn more about jacks and plugs, check out my articles What Is The Difference Between A Microphone Plug And Jack? and How Do Headphone Jacks And Plugs Work? (+ Wiring Diagrams).
If there is an issue with the wiring, hiss, hum, popping, crackling, and other noise can be sent to the speaker and cause significant issues in the speaker performance.
Wiring issues can be a result of any of the following:
- Improperly wired jacks/plugs
- Mismatched or loose jacks/plugs
- Loose or damaged cables
- Loose solder connections
Troubleshooting & Fixing Hum & Hiss From Poor Wiring
To troubleshoot a wiring issue in an audio system, try wiggling the cables around while listening for speaker noise. Do this at a low listening level to avoid hearing and/or speaker damage.
The issue could be a connecting cable, which can be easily replaced or repaired.
Other times, the issue could be within the speaker, which may require dismantling the speaker and re-soldering a connection or replacing a wire.
The issue could also be a plug or jack connecting in the signal chain. This is often the case when the fit of the jack/plug is loose. It’s often best to replace the connector or try a different cable to solve this issue.
That being said, there are many instances when there is no apparent wiring issues but hum, hiss and other noise is still a nuisance in the speaker(s). Let’s now move on to the more difficult-to-diagnose noise issues with speakers.
Ground Loop Noise
Ground loop noise is, unfortunately, a common issue in audio systems particularly in older buildings. It is also known as 50 or 60 cycle hum depending on the country’s AC power mains frequency.
A ground loop happens when various pieces of audio equipment are plugged into different AC outlets. When these pieces of audio equipment are then connected together electrical via signal wires and cables, there is potential for a ground loop.
In the audio system, all AC power mains plugs should have the same ground potential. If the two (or more) AC plugs have different ground potentials, then a ground loop will occur.
Let’s imagine two power outlets (A and B) that have different ground potentials.
Let’s also imagine a piece of audio equipment (a computer) is plugged into outlet A and another piece of audio equipment (amplifier) is plugged into outlet B. These pieces of equipment are then connected together via an audio cable.
The shield of the audio cable is typically connected to the grounded chassis of both the computer and amplifier and effectively closes a loop between outlets A and B. Because outlets A and B have different ground potentials, a ground loop is formed.
The ground loop acts as an antenna to pick up the stray magnetic fields of the power mains (at 50 or 60 Hz). These magnetic fields induce a current in the loop via electromagnetic induction which manifests itself as the dreaded 50 or 60 cycle hum in our speakers.
Troubleshooting & Fixing Ground Loop Noise
Ground loops are easily identified by a trained ear. Simply listen for the 50 or 60 Hz hum in the speakers.
If we do hear this noise and we can see that our audio equipment is plugged into multiple sockets, it is likely that a ground loop is present.
In order to eliminate the dreaded ground loop hum from our speaker(s), we must break the loop. This can be done in several ways.
The easiest method of eliminating ground loop hum is to connect all the audio equipment to a single AC outlet.
This can be done with a power strip (ideally a heavy-duty strip with surge protection). It can also be accomplished with a more reliable power conditioner.
The Furman SS6B (link to compare prices on Amazon and other online retailers) is a great power bar with surge protection. It has 6 outlets.
The Furman M8DX (link to compare prices on Amazon and other online retailers) is an affordable rack-mountable power conditioner with 9 outlets.
Though removing the ground may seem like a good idea to remove ground hum, I strongly advise against this practice. Sure, it may eliminate ground hum but the potential shock hazards that come along with it are not worth the risk.
If plugging all your audio equipment into a single outlet is impractical, there are hum eliminators on the market. These devices act to break the ground loop safely.
Ebtech has multiple quality hum eliminators to choose from. Check out their plug-style Hum X on Amazon.
AC Line Hum
Any electrical device with a motor will produce electromagnetic interference that can show up as hum and noise in our speakers. Household appliances like blenders, coffee grinders and hair dryers are common examples.
Of course, these devices, when turned on, produce noticeable noise as well that will interfere with our listening pleasure. It’s worth noting that the EMI they emit will produce noise within the audio signal as well.
Light dimmers and fluorescent lights also emit this EMI in the audible range.
Troubleshooting AC Line Hum
AC line hum will sound similar to a ground loop. Oftentimes solving the ground loop will eliminate the AC line hum as well but not always.
The simplest way to eliminate AC line hum is to eliminate the devices that produce this noise/interference. This isn’t always easy, though.
Online UPSs (uninterruptible power supplies), isolation transformers and power conditioners can effectively knock out any interference from AC device interference and should be used is AC line hum is an issue.
Though there are plenty of audiophile-grade power conditioners and UPSs on the market, I’d recommend saving your money and opting for a more reasonably-priced model.
The CyberPower CP1350PFCLCD (link to compare prices on Amazon and other online retailers) is one such affordable consumer-grade UPS option that will help in project studios.
Radio Frequency Interference
Radio frequency interference (RFI) is a specific type of electromagnetic interference that happens in the radio frequency band.
I’ve had RFI induce nearby radio station audio into a microphone signal before. However, this is not the most common type of RFI.
As an aside, I used the Shure A15RF (link to compare prices on Amazon and B&H Photo/Video) to eliminate this RFI.
Many of our wireless devices (even Bluetooth devices) use RF carrier signals to transmit data wirelessly. All of these RF signals in our environment can cause noise in our audio systems which shows up in our speaker(s).
Troubleshooting & Fixing Radio Frequency Interference
RFI often shows up when data is transmitted wirelessly. Listen for faint buzzing and hissing when wireless devices are operating near your audio system.
RF filters can be put in-line if RF is overly problematic. The aforementioned EMI-blocking strategies may also do the trick to eliminate RFI.
Another effective strategy is to simply keep unnecessary wireless devices away from your audio system and speakers.
The internal sound cards and motherboards of computers (including smartphones and tablets) can be rather noise. They are susceptible to electromagnetic interference that cannot be eliminated within their structures. Noise can also be introduced in the digital-to-analog converters used at the computer outputs.
Troubleshooting & Fixing Computer Noise
If you’re using a computer to output audio, there is likely hum, hiss or other noise in the audio.
Upgrading the sound card or installing a PCI or PCIe card may help to reduce or even eliminate this noise.
Using high-quality external audio interfaces may fix the issue of computer noise as well. These interfaces often connect via USB, Thunderbolt, or other digital connections.
USB connections are not completely immune to noise, though, and may introduce their own hum and hiss to the speaker.
This is due to stray current leaking into the shielding of the USB cable.
Troubleshooting & Fixing USB Noise
There are three methods for removing USB cable noise.
The first is to use a ferrite noise suppressor sleeve (also known as a ferrite choke). Some USB cable comes with a built-in ferrite choke.
Ferrite chokes can also be bought as clip-on units. Ensure the ferrite choke you purchase will fit on the cable you intend to choke.
For example, the USB-A to USB-B cable that connects my computer to my audio interface is 4 mm (5/32″) in diameter so these Uxcell ferrite chokes (link to check the price on Amazon) would be a great fit.
The second method involves the use of a USB noise filter. These devices split the shield connection and dissipate the unwanted noisy current.
The AudioQuest Jitterbug (link to compare prices on Amazon and B&H Photo/Video) is a great example of a USB noise filter.
The third method is to use a ground shunt. This involves running any wire that’s less resistive than the USB shield alongside the USB cable from the audio device (computer) to the audio interface.
Mechanically-induced hum can be caused by the transformers in the power mains and power supplies of various components in the audio system. Speaker amplifiers may suffer from this and introduce noise to the speaker.
Transformers due to lamination rattle which refers to a DC voltage on the line. No transformer is immune from lamination rattle, though poorly constructed transformers are much more susceptible to lamination rattle noise.
Troubleshooting & Fixing Transformer Noise
If transformer noise is an issue, we may notice that the amount of the noise changes over time since it is dependent on the quality of the AC line voltage.
Listen for noise that is not indicative of a ground loop or RF interference. If the noise changes over time, it could be transformer noise.
If the transformer noise is a persistent issue, putting an AC power regulator between the power mains an the audio systems can help rid of any pesky DC on the power and, therefore, transformer noise from the speakers.
Blown-out speakers may also hiss and hum. Depending on the severity of the blow-out, the speaker may stop working entirely.
Blow-out is an all-encompassing term for a damaged speaker. The most common ways in which speakers blow out include the burning or melting of the voice coil and deterioration/damage to the suspension and speaker cone.
Troubleshooting & Fixing Blown Speakers
Troubleshooting blown speakers involves listening for noise and distortion; limited frequency response; and other non-linearities in the sound of the speaker. We must then investigate the damage that has been done to the speaker.
Oftentimes it’s more cost-effective and simpler to replace the entire speaker. This is the case with many inexpensive and passive speakers.
Other times it’s better to re-cone the speaker, effectively replacing the moving parts of the driver (voice coil, cone, suspension, etc.). This can be done with replacement parts from the speaker manufacturer and a re-coning kit for your specific speaker.
For more information about speaker blow-out, check out my article Loudspeaker Blow-Out: Why It Happens & How To Avoid/Fix It.
What does a blown speaker sound like? A blown-out speaker will often sound distorted or noisy even at low levels. If the blow-out is particularly bad, the speaker won’t even be able to produce sound.
How do you fix speaker distortion? Speaker distortion can happen for a multitude of reasons. The primary reason is that the amp is overloaded. Try turning down the volume so not to overload the amp or the speaker. The there is inherent distortion in the audio signal, play different audio. If the speaker is blown-out, repair it.