Informative articles on Grounding
- Wikipedia
In my 20+ years as Tweek Geek, I have had my fair share of experience with different grounding boxes from many manufacturers. While I have heard improvements wrought by some, I have wondered if this is the high end audio looking for a problem to mystify, complicate and make expensive solutions for.
The truth is maybe, but Audio is a funny, fussy thing. What works great for me and my system, may not benefit you or your system at all. The device I am giving the plans away for will help you determine if you might indeed benefit from a grounding box. It may also totally take care of the issue of ground noise on your system. In the end it will give you knowledge about the type of noise infiltrating your audio system, and help you going forward on how to proceed in the quest for eliminating noise in your system.
Grounding. Necessary & Often Noisy
In audio, grounding is used for safety and for audio signal noise reduction. It is a very important type of noise to attenuate. Everything in your house is dumping noise onto the ground lines, even our beloved audio components may be producing noise. That, along with the noise coming in from outside the house presents a pretty strong case for reigning this noise in.
If you are a typical US homeowner, our home AC grid is grounded, usually by a long copper rod placed several feet deep in the earth, with a ground wire from our breaker box connecting to it. The earth itself is great at absorbing the energy, well sometimes. It can actually fluctuate due to moisture levels in the soil. When it's moist, grounding is more effective, when the soil is dry, not so much. The quality of this house ground is definitely an afterthought in most cases, and could benefit from some intentional fortification.
An audio grounding box is meant to supplement the existing house ground, or perhaps provide a separate ground path for audio signals (as opposed to audio power). A grounding box is usually filled with minerals and elements with a central conductor or series of conductors inside the box running through the material. The conductor or conductors are connected to a binding post or some type of connector on the outside of the box. A specially made, usually highly conductive "Grounding cable" is connected from a component's signal or chassis ground (never both together) to the binding post on the box. The intention is to create a low resistance path for ground noise and static electricity to flow through and be absorbed by the absorbing elements inside the ground box.
Both the house ground and the grounding box provide a low resistance path to the ground plane, where the noise is drawn away and absorbed, or converted to heat. The proximity of the ground box may provide an additional advantage over the ground rod outside your home.
They work, sometimes. And sometimes they don't do much. It really depends on your home's electrical grid, the level of noise on the ground leg of the AC, and the quality of grounding that your house has. You see, everyone's AC is different. Your AC in New York City is different in terms of noise, distortion and harmonics that ride the AC lines than my AC in Austin Texas. What works for you may not work for me.
So before spending a few grand on a box, why not pony up 50 or 100 dollars, order up a few parts and make 5 or 10 of these filters to see just how much you may benefit from a filtered ground?
The DIY Ground Filter
This method of attenuation of ground noise (and the focus of my post today) is through using a large, doughnut shaped ferrite, but only on the ground. Ferrites are a type of frequency dependent resistor. At certain frequencies, their resitance increases, attenuating noise in the frequency bands that they are resistive in. They are fantastic at doing their job, but for some reason can really suck the life out of the music if over used. We get around the negative sonic aspects of the ferrite by using it ONLY ON GROUND. Not incoming hot or neutral AC, not signal conductors.
So with one of my ground filters, you can, for $10 put together a ground filter that plugs into any AC socket and will drain away noise within a certain bandwidth well outside of the audio range. This somehow effects the sound in the audible range greatly, IF you have a ground noise issue to begin with. I encourage you to build 5 or so of these. place one adjacent to the outlet that your power conditioner is plugged into. Place them around your listening room, or place them around large appliances that may be polluting the electrical ground.
First, the list of ingredients:
- male 3-prong electrical plug - $3.75
- Grounding wire 12 awg I prefer solid core wire because it holds it's shape - .36 per foot
- Ferrite to wind the wire around - $5
Assembly
- cut about 36" of wire, and start wrapping one end around the Ferrite "doughnut". The interesting thing here is that by wrapping the wire around the ferrite, you increase the level of attenuation by 6dB per turn. It's pretty powerful.
- Once you have all but about 3" of the wire wrapped around the ferrite, stop, and strip about 1/2" off of the end of the excess wire.
- Connect the stripped end of the wire to the GROUND terminal of the male AC connector
- Close up the body of the connector and you are done. You can use electrical tape to wrap around the entire contraption if you would like, just to keep things tidy.
- Plug in to the wall and listen for any changes.
Of course the best place to put such a filter is as close to your audio components as possible, so start there. if you have a power conditioner, then the outlet adjacent to where that is plugged in should be beneficial. Spreading out from there, try covering the open receptacles (or one filter per duplex) within the room, then try placing on outlets adjacent to power strips and appliances in your home.
These devices will absorb ground noise within the bandwidth of the ferrite. In this case from 1 to 100mHz.
Now audiophile grounding boxes may work with different frequencies, but they are essentially doing the same thing. Getting rid of noise. You may find these filters placed strategically throughout your home may be very effective, negating the need for an audiophile ground box. They may not do anything, especially if you don't have much of a ground noise issue on your home circuit. But at least you can find out without spending thousands of dollars first.