Adventures In Audio

What's the difference between Earth, ground and screen?

Do you know what the difference is between Earth, ground and screen? Are they all the same, or does the way in which they are applied matter?

Audio equipment, analog and digital, works using varying voltages. A voltage is always measured between two points. It is meaningless to say that any one point in a circuit is at a certain number of volts, unless the reference point is also quoted.

For mains-powered equipment, that reference point is always Earth - capitalized because it is the planet Earth. The Earth is so big in comparison to any source of electricity - even the Hoover Dam, that all electrical currents that flow into it average out and the Earth's voltage is taken to be the ultimate zero volts reference.

So any voltage inside mains-powered equipment can be measured and quoted with reference to Earth. The chassis of the equipment will be connected to Earth to make sure it is at zero points, and the circuit will also be connected to Earth in order to supply the necessary zero volts reference to all of its elements, either through the chassis or separately.

'Ground' is often used as a synonym for Earth.

Connection to Earth is usually via the earth of the mains socket. This in turn is electrically connected to Earth, often through the plumbing system. However if this option is not available then a copper spike can be driven into the ground to provide the Earth connection. Whatever method is used, earthing or grounding can be more effective or less effective - a copper spike in dry soil or sand will not make a good connection to Earth.

A 'screen' is a metal sheath around a signal-carrying conductor. The idea is that any interference that might otherwise work its way into the conductor will be dispersed in the screen before it has chance to get through. This works a whole lot better if the screen is connected to Earth, so interference currents are swiftly and efficiently carried away.

Equipment that is mains-powered but not itself earthed at the mains connector nevertheless finds its earth through the other equipment to which it is connected. If used alone, then it is not earthed, but interference is dispersed within the metal parts of the chassis of the equipment. The same applies to battery-powered equipment.

Tuesday October 31, 2006

Like, follow, and comment on this article at Facebook, Twitter, Reddit, Instagram or the social network of your choice.

David Mellor

David Mellor

David Mellor is CEO and Course Director of Audio Masterclass. David has designed courses in audio education and training since 1986 and is the publisher and principal writer of Adventures In Audio.

Learn Pro Tools with our amazing range of video courses

Pro Tools video course catalog

Browse Pro Tools courses...

Learn Logic Pro with our amazing range of video courses

Logic Pro video course catalog

Browse Logic Pro courses...

Learn Cubase with our amazing range of video courses

Cubase video course catalog

Browse Cubase courses...

Audio Masterclass gives you all the technical knowledge and skills to bring your musical dreams to life

The Audio Masterclass Music Production and Sound Engineering Course

Get the most from your studio with the Audio Masterclass Music Production and Sound Engineering Course.

Learn more...

More from Adventures In Audio...

Your power amp is average - Here's why

Adding tube warmth with the Freqtube FT-1 - Audio demonstration

Adding tubes to a synth track with Freqport Freqtube

The tiny amp that does (nearly) everything

Can I unmix this track?

Why you need a mono amp in your system - Fosi Audio ZA3 review

Can you get great earbud bass with Soundpeats AIR4 Pro?

24 bits or 96 kHz? Which makes most difference?

16-bit vs. 24-bit - Less noise or more detail?

Are these earphones REALLY lossless? Questyle NHB12

Could this be your first oscilloscope? FNIRSI DSO-TC3

OneOdio Monitor 60 Hi-Res wired headphones full review

Watch me rebuild my studio with the FlexiSpot E7 Pro standing desk

Can a tiny box do all this? Testing the Fosi Audio SK01 headphone amp, preamp, EQ

Hi-Fi comfort OVER your ears? TRUEFREE O1 detailed review

Get the tube sound in your system with the Fosi Audio P3

Any studio you like, any listening room you like - For producers and audiophiles

Hidden Hi-Fi - The equipment you never knew you *didn't* need - Fosi Audio N3

Adding tubes to a jazz mix with Freqport Freqtube

Adding tubes to a rock master with Freqport Freqtube

Adding tubes to female vocals with Freqport Freqtube

Adding tubes to male vocals with Freqport Freqtube

Adding tubes to real drums with Freqport Freqtube

Adding tubes to a bass guitar with Freqport Freqtube