Insulated, Isolated Grounds At Home

NOV/DEC 2002 TIP

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Insulated, Isolated Grounds at Home

Archived Article 2 for Recording Magazine Reader's Tip 5

From The Recording Engineer's Quarterly Archives

BY ROBERT DENNIS

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All studios, big or small can have problems with buzzes and hums. These types of problems can quickly make the product put out by the studio unprofessional or even unusable.

Step 1 of Debuzzing & Unhumming is to establish a good ground. A professional studio would call in an electrician to install insolated and isolated ground plugs. This would assure that the ground pins used in the studio were at or very close to "0 volts" with no stray hum.

The cost to the professional studio could be anywhere between $150 and $500 depending on circumstances. At home you can install an insolated and isolated ground for your project studio that is as good as the electrician's, but for an out-of-pocket cost between $10 and $20.

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Why You Need A Good Ground

In theory, any of the outlets in a building are supposed to have "0" volts on their ground pins. NOT SO. Most outlets have a small voltage (1/2 to 1 volt). This is a high "line level" in audio. the same level as the audio signal you want. As a project studio grows in capability, this poor ground starts introducing hum into the equipment.

The smaller project studios may not need a better ground now, but could well need one in the future.

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Making A Insulated/Isolated Ground adapter

A piece of equipment can work with a broken ground wire but become an "antenna" for hum & buzz.

A grounding adapter is sold in many hardware stores for about a dollar. It is designed to provide a ground to a 2 wire outlet by attaching a grounding pit to the faceplate screw at the outlet If the unit had instructions, it would say to attach the green wire coming out of the adapter to the faceplate screw on the outlet.

If We are going to modify this adapter so that the ground wire of the adapter attaches to a long wire that is properly grounded.

The ground wire is long enough to reach the nearest cold-water pipe. If the wire is less than 25 feet use a #12 green electrician's wire. The local builder's supply outlet will sell this by the foot. If the run is much more than 25 feet you should use a #10 wire.

You splice one end of the wire to the small ground wire of the adapter. You can twist these wires together and solder + tape them. You can also simply crimp them.

You will also buy from the builder's supply store a grounding clamp for pipes. This will be attached to the other end of the wire.

Even if you have a grounded outlet - use the adapter to give you an fully-insulated and isolated ground system

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