Acceptable Level Ground/Earth Noise

Dedicated earth ground? As not connected to the main grounding system of the electrical service of your house?

If that is the case you have two earth connections that are not electrically connected together and therefore are not of equal ground potential. Not only is it dangerous it can cause 60 Hz hum.

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"From Henry W. Ott’s big new book "Electromagnetic Compatibility Engineering"

3.1.7 Grounding Myths

More myths exist relating to the field of grounding than any other area of electrical engineering. The more common of these are as follows:

1. The earth is a low-impedance path for ground current. False, the impedance of the earth is orders of magnitude greater than the impedance of a copper conductor.

2. The earth is an equipotential. False, this is clearly not true by the result of (1 above).

3. The impedance of a conductor is determined by its resistance. False, what happened to the concept of inductive reactance?

4. To operate with low noise, a circuit or system must be connected to an earth ground. False, because airplanes, satellites, cars and battery powered laptop computers all operate fine without a ground connection. As a mater of fact, an earth ground is more likely to be the cause of noise problem. More electronic system noise problems are resolved by removing (or isolating) a circuit from earth ground that by connecting it to earth ground.

5. To reduce noise, an electronic system should be connected to a separate "quiet ground" by using a separate, isolated ground rod. False, in addition to being untrue, this approach is dangerous and violates the requirements of the NEC (electrical code/rules).

6. An earth ground is unidirectional, with current only flowing into the ground. False, because current must flow in loops, any current that flows into the ground must also flow out of the ground somewhere else.

7. An isolated AC power receptacle is not grounded. False, the term "isolated" refers only to the method by which a receptacle is grounded, not if it is grounded.

8. A system designer can name ground conductors by the type of the current that they should carry (i.e., signal, power, lightning, digital, analog, quiet, noisy, etc.), and the electrons will comply and only flow in the appropriately designated conductors. Obviously false.

Henry W. Ott

• https://books.google.com/books?id=2-4WJKxzzigC&pg=PA119&lpg=

almarg said:

Jim (Jea48), thanks for posting the Henry Ott writeup. I’ve seen that before and I always get a chuckle out of it, especially no. 8. For others who may not be aware, Mr. Ott is one of the world’s leading authorities on grounding and various other aspects of electronic design that often tend to be mysterious even to trained EEs.

Hi Al,

I think Ott hit the nail on the head with #4.

4. To operate with low noise, a circuit or system must be connected to an earth ground. False, because airplanes, satellites, cars and battery powered laptop computers all operate fine without a ground connection. As a mater of fact, an earth ground is more likely to be the cause of noise problem. More electronic system noise problems are resolved by removing (or isolating) a circuit from earth ground that by connecting it to earth ground.

AL,

I agree with your post above about disconnecting all that earth grounding that srafi has added, connected, to his audio system. It does nothing for the SQ of his audio. If anything it adds noise. The only ground he should have connected to his audio system is the safety equipment ground.

srafi said:

I did forget to mention it gets louder when I touch the tone arm so could be something else.

To me that sounds like the tone arm is not grounded to the signal ground of the phono preamp. LOL, I’m almost hesitant to use the word grounded. Some take the word as meaning mother earth ground.

If the TT has a ground wire and srafi has it connected to the chassis of the phono preamp it could be the ground wire connection is open/broken. If that is the case there is a good chance it would be inside the TT. For a simple test he could connect a wire at the phono preamp chassis and then touch the other end of the wire to the tone arm or to the tone arm support tower. If the hum stops he has found his hum/buzz problem.

I would also check the cartridge phono wires to make the connections are good.

Jim

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@srafi,

I was searching for some information on your turntable. I ran across the owner manual and found this note.

2.2

To avoid hum noises it can be necessary to ground the bearing. For that please plug in the provided ground cable into the hole of the screw from the bearing at the bottom of the turntable.

It doesn't say were to connect the other end of the cable/wire. I would think it should connect to the phono preamp chassis ground lug/terminal.

Do you have this ground wire connected to the turntable? If so where do you have the other end connected?

Another question. What is the arm you are using on the table? What material is it made of? 

Clearaudio Performance DC Turntable owners manual.

http://clearaudio.de/_assets/_pdf/manuals/turntables/CA_Performance%20DC_E.pdf

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