Or… “Chasing Hum and Buzz and Pops and Hiss, oh my!”
Unwanted noise in your audio gear can be difficult to track down, but a better understanding of how to evaluate the noise and identifying the type of noise itself will give you a head start on finding it’s source.
First, let us define the most common unwanted audio noises. Understand that all of these sounds (except pops) will be present in all audio gear to some degree, the trick is get make them quiet enough in your system to not be annoying. And if you’re mixing “pro” and “consumer” equipment, you can run into balanced vs unbalanced wiring and vastly different signal levels, which contribute the same noises but require different solutions.
Definitions
- Hum
Hum is a constant low frequency sound. In places with a 60 Hz AC system, it sounds like (insert sound here) and in 50 Hz places it sound like (insert sounds here).
If you look at these on a scope, they look like this:
(insert pic)
Hum is typically caused by ground loops, poor/bad signal wiring shielding, or radiated emf. These can be very tricky to run down. - Buzz
Buzz is more “raspy” sounding than hum, and usually twice the frequency of your AC mains, eg 120 Hz in the USA, 100 Hz elsewhere.
In places with a 60 Hz AC system, it sounds like (insert sound here) and in 50 Hz places it sound like (insert sound here).
If you look at Buzz on a scope, it looks like this:
(insert pic)
120/100 Hz Buzz is almost always caused by power supply issues, typically bad filter caps. - Pops
Pops are random spitting noises, usually at a fairly low volume but quite objectionable due to their random nature.
(insert sound here)
Pops are usually caused by bad connections or old resistors that have moisture in them. In vintage tube equipment, it’s often the plate or cathode resistors.
For mechanical devices like speakers, microphones, and phono cartridges, pops can be caused by mechanical failure, or driving the element beyond it’s max capability. Phono cartridges can encounter static electricity issues from playing records as well.. - Hiss.
Hiss is a random full spectrum noise, similar to inter station FM radio hiss. It’s technically a white noise, which is an equal energy per frequency noise, so it sounds “tizzy” and “bright”.
All audio equipment has some hiss, and with enough gain you will hear it. With no sounds playing and the volume up enough, if you bring your ear near your speakers tweeter , you will hear hiss . (Be very careful to not accidentally play something with your ear that close, you can easily damage your hearing.)
(insert sound here)
Diagnosis
Since all these noises are routinely present in some amount, you must evaluate the noise levels in your system and listening room as to how objectionable they are. For example, high sensitivity speakers will expose a lot more of these noises than a lower sensitivity ones will. And you should still do this evaluation even if you have test equipment, as it is common to have a piece of gear that meets it’s manufacturing specs but still has noise issue in your listening environment.
Let’s look at how to do this evaluation. First turn your system on and play some music on your usual source at your typical preferred loudness level in your usual listening spot. Now pause the music, and listen for any objectionable equipment noise.
If you don’t hear any, great! Go forth and enjoy!
If you do hear objectionable equipment noise, note which ones are present and whether they are in one or both/all speakers.
Next, lower the volume, switch to your next source, and repeat your evaluation. Continue until you’ve checked all your sources. Now you have a list of any problem areas and how many channels are involved, two major clues you’ll need to track down the issues. It is common for phono and mic inputs to have more hiss, as those preamps have a lot more gain then line inputs.
Lastly, turn the volume down all the way, and listen from your normal listening position, then go up to your speaker and put your ear a few inches away from the various drivers and note what noise you hear (if any) from each of the drivers.
Lastly sit quietly for a few moments and listen closely to the room background sounds.
OK, now you are armed with some data, let’s analyze it!
( in process )
Last Updated on 2026-02-04 by Daev Roehr