Hi,

I am starting this thread to collect information about Ground Loop and Radio Frequency Interference. Hopefully it will be helpful for those suffering either or both of these problems.

My experience re Ground Loops. My Wife and I bought a new home. In our old house there was hardly any problems with interference but in the new home I have had hum and crackle in my monitors and have had to turn their volume down quite a bit. Eventually I bought a ground loop isolator that removed essentially all the crackle and almost all the hum even with the monitors at full volume. I would guess hum is reduced about 97%. At least that is how it seems to me. I simply installed the Isolator between the audio interface and monitors.

My experience re RF interference. When I use my Guitar through my amp I suffer RF. You can generally confirm the hum is RF if the sound changes when you move around with your guitar. iIt seems to depend on the time of day or/if I have a computer turned on.

I tried ferrite beads without success and am continuing to trouble shoot the problem. It happens with my Gibsons but not with my Fenders. I am told that is due to the noise cancellation on the Strat pick-ups.

I am hoping others will chime in with their experience.

All the best,
John

RF interference form computers will certainly go away or diminish if you turn the computer off.
 
It's unusual for Fender guitars to be noisier than Gibsons unless the Fenders have humbuckers (or "silent" single coils which are really humbuckers in a single-coil case) and the Gibbons have (single-coil) P90s. Though Gibbons with humbuckers can and do still pick up some noise, as will the guitar lead and often pedals and amp as well if you are using them.
 
Wi-fi can also be a source of noise - usually showing up as a whining at around 2.4KHz and 5KHz, which are the usual bands routers and computers transmit on.
 
Getting further away from the source of noise, if you can, is the best answer to the problem. Ferrite beads tend to not do very much in the audible frequency range, and ideally need tuning to the circuit they're filtering as well.

Hi tlw,

Thanks for the reply. You must have misread my post about the guitar interference. The Fenders are fine. The Gibsons are the problem. I do turn the computer off for practice, but I need it on to record.

John

Have you tried a higher end instrument cable with better shielding?

You could check for "proper" wiring, i.e. hot, neutral and ground all properly connected through to your wall outlets. A receptacle checker like this can do it. The next thing to worry about is whether you have two different circuits (from two different circuit breakers) feeding wall outlets near your equipment. If you use both outlets, there could be unbalanced current flow, and therefore high 60HZ emissions, heard as hum from any sensitive equipment.
 
There is a different kind of house wiring error that is harder to find, but probably not common. It happens when two different circuits both feed to a distant box (say lights/switches on two different circuits) and have their neutrals joined. This can cause massive electrical noise all along both circuits through the walls, as current is no longer balanced in equal but opposite directions in the wire pairs. When this happened at my house, it was causing CRT monitors to flicker horribly unless all the lights were out. I used an EMF/ELF meter to locate the wires in the walls and find the box where they joined.
 
That same meter spotted massive noise near the outside power connection to the house. That can be pretty common, depending on how the power company's feed interacts with a local ground, making some part of the power feed unbalanced, thus emitting 60HZ EMF.

several things - as bvideo noted, check the wiring, try to use a single outlet to power everything or two outlets you verified have matching hot, neutral, ground. if you have a tube monitor versus LED etc, you'll find the monitor causes a lot of noise. if you afford a properly UPS to run everything through, then you'll get stable voltage, no noise etc.

tlw
Wi-fi can also be a source of noise - usually showing up as a whining at around 2.4KHz and 5KHz, which are the usual bands routers and computers transmit on.

Wi-fi is 2.4GHz and 5GHz. It won't even bother your dog. Not sure about the other frequencies associated with computers - USB and Ethernet should also be way beyond audible frequencies. There may be other stray RF from the components in the case that could cause problems.
 
Transformers that drive LED and other lights can be an issue. These convert mains voltage to 12V DC or similar, and generally sit near the light. I know these can cause noise in my guitar unless I'm using the humbucker pickup.
 
Cheers, Peter.

Several years ago I had an untraceable hum somewhere in my mass of wires.

Ultimately with one device I had I added a three prong to 2 prong electrical plug adapter (got rid of the ground).
It cost me I think 49 cents.

It made all the difference in the world. Suddenly my entire studio was perfectly silent.

1. Balance everything that can be balanced. Everything between your computer I/O box and speaker amplifier should be a balanced connection using high quality wire.
2. Shield everything else. If your fenders aren't making noise, then either they're well shielded or making use of noiseless pickups or probably both. When I took my chibson wes paul out of the box (don't judge me) the hum and noise was almost as loud of the guitar itself. Once I changed out the pots and dropped in a set of Seymour Duncans and lined everything with copper, the guitar sounds great and is absolutely dead silent. Even when I kick the pickups into single coil mode. Even with all my computer monitors on and the overhead lighting dimmed.

I don't hear any interference or buzzing in my monitors (maybe my Furman power conditioner helps, I don't know) but I do get quite horrendous buzzing from my Telecaster sometimes. I know they're pretty noisy at the best of times but it makes recording anything with anything more than the lightest of crunch sounds problematic. What I've found though is that there is a "sweet spot" at which I can position my guitar which virtually eliminates the hum. Unfortunately for me it happens to be facing away from my DAW with the front of the Telecaster tilted toward the floor