The issue of audio performance and the safety-earth impedance.

Posted by Al Sekela (A) on September 27, 2008 at 11:33:04

In Reply to: RE: Should I re-ground? posted by jea48 on September 26, 2008 at 22:04:19:

Charles is correct that a completely ungrounded system has the chance to sound better than any system that includes an AC 'ground' (safety-earth) connection.

This is because audio equipment power supplies have finite capability to block electrical noise present on the AC power connection. The typical household AC 'ground' wiring is extensive and the actual earth connection point is typically dozens of feet away from the audio system. This means the AC 'ground' wiring carries all manner of higher-frequency electrical noise. Connecting an audio system to it allows this noise to be added to the self-induced and broadcast noise already present in any system, and the noise carried by the hot and neutral AC wires. Multiple AC 'ground' connections in an audio system result in ground loops that increase the susceptibility of the system to noise.

Given that much audio equipment is designed with an AC 'ground' connection, and that lifting this ground is dangerous, the best thing to do is to ensure the impedance from the system AC receptacles to the actual earth connection is as low as practical. This includes ensuring the earth connection has the lowest impedance the code allows.

Note that the frequency range covers all the noise frequencies that can affect the audio system, typically from DC to above 100 MHz. Heavy-gauge solid wire has some inductance of its own that decreases slowly as the diameter increases. Using heavier wire than required makes little difference in the overall impedance. The transmission line effects become important at higher frequencies. Thus, while attention to the AC earth connection and safety-earth wiring will help, it will not completely resolve the noise issues at higher frequencies.

Handy calculator for straight-wire inductance. (Open in New Window)

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Follow Ups Full Thread

Topic - Should I re-ground? - RickeyM 09:46:50 09/26/08 (19)

RE: Should I re-ground? - jea48 22:04:19 09/26/08 (13)

My new house in NM has flexible plastic pipes. - Norm 06:33:46 10/04/08 (4)

RE: My new house in NM has flexible plastic pipes. - jea48 11:47:28 10/05/08 (3)

It was built in 2002. - Norm 05:42:56 10/06/08 (2)

RE: It was built in 2002. - KLS 12:39:05 10/10/08 (1)

I doubt if it can be used as a ground. nt - Norm 12:59:32 10/14/08 (0)

RE: Should I re-ground? - Slick 11:43:06 09/28/08 (5)

Nice post.... But please reread my first post before responding to this one. - jea48 22:25:12 09/28/08 (1)

RE: Nice post.... But please reread my first post before responding to this one. - Slick 04:51:24 09/29/08 (0)

Friendly counterpoint - cdb 13:47:13 09/28/08 (2)

RE: Friendly counterpoint - Slick 04:44:35 09/29/08 (1)

RE: "...our local jurisdictions require..." - cdb 19:09:07 09/29/08 (0)

RE: 2 rod electrodes - cdb 12:04:34 09/27/08 (0)

The issue of audio performance and the safety-earth impedance. - Al Sekela 11:33:04 09/27/08 (0)

There should be one there already - Russ57 13:51:00 09/26/08 (0)

Hire a qualified electrician. - Al Sekela 11:46:28 09/26/08 (3)

RE: Hire a qualified electrician. - RickeyM 20:43:31 09/26/08 (0)

RE: Hire a qualified electrician. - sailor321 13:02:56 09/26/08 (1)

RE: Hire a qualified electrician. - Melchior 11:09:07 09/27/08 (0)

Follow Ups

The issue of audio performance and the safety-earth impedance. - Al Sekela 11:33:04 09/27/08 (0)

The issue of audio performance and the safety-earth impedance.

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