All sound systems can suffer from unwanted noise from time to time.
The source of any new noise can be fairly easy to locate and eliminate in well-installed systems. However, there are times when noise from the sound system can be difficult to find and challenging to fix.
Here are some tips that can help solve the problem of buzz and hum in church sound systems.
Buzz vs. Hum
Buzz and Hum are different.
They sound different and they have different causes.
This means that fixing them may require different solutions.
Buzz is often a higher pitched noise that can even crackle at times. (Imagine the zzzzzzz and crackle in a bad AM radio station.)
Hum tends to sound lower pitched and it will likely have a tone signature that you can actually hum along with. (Imagine a low or mid-frequency mmmmmm.)
Finding and Fixing Buzz
Electrical noise or interference are typical causes of buzz that in the audio signal.
This interference can come from bad power supplies or circuits (dirty power), lighting dimmers, fluorescent light ballasts, or nearby high voltage electrical systems.
Tip #1: Power All Audio System Components With Dedicated Circuits
This tip should correct help solve electronic noise due to power issues. These circuits should not have any non-audio related equipment plugged into them. This includes lights, appliances with motors, and anything else that is not part of the audio system.
Tip #2: Use Shielded Audio Cable
The best way to prevent buzz in the audio signal chain is to use quality shielded audio cable and then route that cable so that it is several feet away from electrical equipment that can cause noise.
Tip #3: Keep Low Voltage Audio Cables 18” to 3’ (0.5-1 meter) From Higher Voltage Cables and Equipment
This distance is especially important when cables are running parallel with each other. Insulated cables can be closer together or even touching if they are crossing at a 90˚ angle.
Tip #4: Inspect Audio Cables
It is also possible that a damaged cable or a bad shield is the culprit in allowing buzz to get into the audio system. Inspect all audio cables for proper functionality and make sure the shield is not cut or crushed.
Tip #5: Use a Power Conditioner or Separate Circuits
It may be necessary to use a quality power conditioner or even separate power circuits to eliminate interference from other electrical systems. (Consult with an experienced electrician if this is the case.)
Tip #6: Conduct a Radio Frequency Survey
Wireless microphone systems can also be a source of buzz or static if there is frequency interference or the electronics in the system are no longer performing as intended. If a simple change in the frequency/channel does not solve the problem, it may be a good idea to do a radio frequency survey to determine the source of the noise before purchasing new equipment.
Finding and Fixing Hum
Hum can be easier to find and faster to fix than buzz, and it is almost always caused by a ground loop.
There are a lot of complicated ways to describe and diagnose this problem, but the most common instance where hum happens is when two different pieces of equipment are plugged into two separate power outlets and then connected with an audio cable.
There can be a difference in “potential” between the two different power outlet’s ground connections. One outlet’s grounding conductor (the third prong on most outlets) may have more or less resistance to “earth ground” than the other.
Don’t worry if that sounds confusing. The important thing to know is that this is an electrical grounding issue and it can be fixed fairly easy.
Fun Fact: The sound of a ground loop changes depending on what country you are in. Hum in North America starts at around 60 Hz and its related harmonics (120 Hz, 240 Hz, 480 Hz, etc.). Hum in Europe starts at 50 Hz and its related harmonics (100 Hz, 200 Hz, 400 Hz, etc.). This is due to the frequency of the electrical grid and power generation system.
Tip #1: Lift the Shield Conductor on One End of the Audio Cable That is Affected
This is easy to do with a common direct box (like when a bass guitar plugs in and the instrument level signal converts to mic level). Most direct boxes (like the [amazon_textlink asin=’B0002DUQ7C’ text=’Whirlwind Director’ template=’ProductLink’ store=’churc0da-20′ marketplace=’US’ link_id=’6f3b631a-a96c-429e-9836-cd511483cddf’]) will have a ground lift switch that will lift the shield and eliminate the ground loop.
Tip #2: Use an Isolation Transformer
Another way to get rid of hum is to use something called a [amazon_textlink asin=’B003MLBEW2′ text=’1:1 isolation transformer’ template=’ProductLink’ store=’churc0da-20′ marketplace=’US’ link_id=’1f783a64-5b2f-4a29-93d3-d4ea787de6f7′]. This is NOT a signal converter (like a direct box), it simply connects in-line with the signal and allows it to pass through a basic transformer.
The transformer will let the clean audio signal pass through while it blocks the hum from crossing over to the other side.
A direct box and an isolation transformer can be very handy to help troubleshoot and provide a quick fix until you can find a more permanent solution.
Tip #3: Check the Cable Length
Cable length can also cause audio noise issues, especially with 1/4″ instrument cables.
Use shorter instrument cables and make sure they don’t wrap around or run too close to power cables. The recommended maximum distance for unbalanced (2-conductor) instrument cables is about 20’ (6 meters).
The Cheater Plug
OK, you might have guessed this was coming, but I have to say it…
Don’t use a “cheater plug” to lift the grounding conductor of a power cable.
Will it work to stop the hum in your sound system? Yes. (But it depends on what piece of gear you use it with.)
So why shouldn’t you use it?
Lifting the equipment ground from an electrical device creates an unsafe operating condition that could cause big problems if something goes wrong or if an outlet is wired incorrectly.
There have even been singers and guitar players electrically shocked on stage because of bad grounding. It’s not something you want to mess with.
It is best to use the methods discussed above to isolate the ground/shield on the audio cable.
And if that doesn’t work, use something like the [amazon_textlink asin=’B0002E4YI8′ text=’HumX adapter’ template=’ProductLink’ store=’churc0da-20′ marketplace=’US’ link_id=’95683ffb-346d-4585-ba49-51bdc49e2962′] from Ebtech to stop the noise while maintaining a safe electrical ground connection.
Have I used a cheater plug? Yes.
Do I have one in my “fix it” kit? Yes.
But I ONLY use it for troubleshooting purposes to help identify a piece of equipment that may be causing a problem.
Using a cheater plug can assist in isolating a bad power supply or equipment with a bad ground connection. Once you find that piece of gear, it should be removed from service or plugged it into a quality power conditioner or separate power circuit. Swapping out the power supply may also be an option with some equipment.
Do not use a cheater plug, even “temporarily”, for active system use. It might work to remove the hum, but it could be at the price of an unsafe and hazardous electrical system.
- Buzz is higher pitched and sounds like a zzzzzz or crackle.
- Bad power supplies, noisy electrical circuits, and lighting dimmers can create buzz.
- Buzz can be fixed by separating power and audio cables, fixing audio cable shielding, and using quality power conditioners on all audio electronics.
- Hum is often a lower pitch and has a distinct mmmmmm tone character.
- A ground loop between two different audio components can cause hum.
- Hum is easily fixed by using a ground lift switch on a direct box, inserting a 1:1 transformer, or using a grounded power adapter like the HumX.
Buzz and hum can be a real distraction in the mix, so take the time to troubleshoot and fix the issues whenever they start.