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Acceptable Level Ground/Earth Noise

Hi Everyone
I have a dedicated earth for my audio system.  I was digging a bore for water and lost the rod so decided to dedicate that bore for Earth.  It is about 100 feet deep an is in water.  The line runs straight to my dedicated audio room and is shared among the various audio components.  
I am running a Clearaudio DC preformence through an Avid Phallus phone stage hooked up to a ML No.  38s pre.  The cartridge is a clear audio virtuoso MM.  The ML volume level goes to 92 and the hum appears at 60. Previously when the earth was shared the hum was almost unbearable at 60 but now is significantly reduced. 
My question is that is the hum just part of the analogue experience or should it be absolutely quite? 
srafi
erik_squires
16,046 posts
 
@srafi

Your utility pole does not provide a ground, it provides a neutral. It’s up to the service entrance to provide a suitable ground. You MUST bond ALL grounds together, and bond that to the neutral coming off the pole.

Having said that, you may use as many ground rods as you’d like. :) What you cannot do is arbitrarily use one rod for one room and another for the rest.

The reason for this is that is prevents the safety ground from working correctly. If a short develops to a case, and this independent ground rod is 10 feet from the house ground rod it can be many volts different than your neutral now. 10s to hundreds. It’s worse with dry soil.

The safety ground should guarantee that the case of your electronics is 0 volts, but if it's at some other, random point, it could be quite higher than 0. That's where you loose your life. :)
jea48
4,423 posts
 

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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jea48
4,423 posts
 

@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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atmasphere's avatar
atmasphere
11,793 posts
 
I did forget to mention it gets louder when I touch the tone arm so could be something else.
Most definitely! The tone arm tube should have continuity to the chassis of your phono preamp. If it does not, hum is a likely result.
Is some level of hum part of an analogue setup or should it be absolutely quite?
Hum is not part of the analog experience. You might get hiss but hum is an indication of a problem somewhere.
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