Audiophiles journey to solve RFI EMI problems![Objectively]

[gobble]

However, I was under the impression that Gobble was referring to the chassis earthing for safety reasons which still doesnt get solved with the preamp grounding in place.
cheers
Sridhar

Yes that is what I was talking about.

Good discussion. Learning a bit as we go along ...

Cheers

 

[IndianEars]

Hi Sridhar, Thanks for your post and feedback. I agree with you that in some equipment, the Signal ground ( eg the body of the female RCA ) shows 'electrical continuity' with the chassis. However, the neutral from the wall will Always be isolated electrically (no DC continuity) from the chassis.

SBFX I LOVED your example of the Car 'ground'. Excellent. Thanks :clapping:

However

So within one system--say an AV receiver--the ground path may be tied to the chassis and one of the prongs on the AC plug or the third prong an a 3-prong plug,

Would just like to re-state that the Chassis can / will Never be directly connected to either the Neutral or live.... The chassis can ONLY be directly connected to the large Ground pin of Mains Ground.

I would like to refer those interested in Grounding to Appliance classes - Wikipedia, the free encyclopedia

There are 3 Classes of Grounding:

CLASS 1 is Grounding where the Chassis is connected to the Electrical Ground.

CLASS 3 is for Very Low voltage appliance that will not normally cause a shock ( typically below 30 V DC )

What we are discussing is CLASS 2:

A Class II or double insulated electrical appliance is one which has been designed in such a way that it does not require a safety connection to electrical earth (US: ground).

The basic requirement is that no single failure can result in dangerous voltage becoming exposed so that it might cause an electric shock and that this is achieved without relying on an earthed metal casing.

 

[arj]

Here below is a good explanation of Floating Ground;

Floating Ground
Electrical circuits, however, don't necessarily have to be connected to a true earth ground; they may operate with a kind of "floating" ground. In fact, for the designer and engineer, the sense of "ground" may just become an intellectual convenience. For example, a flashlight and other battery-operated devices--even your car--work perfectly well without being connected to a true earth ground. In a car, the negative battery post and the chassis frame serve as the "ground" to complete the electrical circuits in the car, yet the entire car is insulated from the real earth by the rubber tires. In fact, the car is a good example of a self-contained electrical system tied to a common ground--the car chassis and the negative battery terminal. All the electrical devices on the car are tied to that common ground path through the metal car frame and body.

So within one system--say an AV receiver--the ground path may be tied to the chassis and one of the prongs on the AC plug or the third prong an a 3-prong plug, or it may not, in which case it could use an internal "floating" ground that's not connected to the chassis.


Regards,

Satyam Bachani.

Satyam , I just got a bit confused..in layman terms, is this how it is done ?
- Disconnect the Earth wire from the plug of all components except the preamp
-connect all the ground temrinals to the earth of the preaamp

Also, for Star wiring, is it enough to create a new distribution box which is star wired and connect all components to that ?

 

[keith_correa]

My amp power is via 2 poles and on the back panel, away from the power cord socket, there is a separate screw in type socket marked "Gnd". What Ground is this? What should it be connected to?

 

[santhosh]

My amp power is via 2 poles and on the back panel, away from the power cord socket, there is a separate screw in type socket marked "Gnd". What Ground is this? What should it be connected to?

That is usually used to ground the tonearm of a turntable to the chassis of an integrated amp or in a preamp. Alternatively one can ground their TT to the phonostage which in turn gets grounded to the preamp via RCA cables.

 

[keith_correa]

That is usually used to ground the tonearm of a turntable to the chassis of an integrated amp or in a preamp. Alternatively one can ground their TT to the phonostage which in turn gets grounded to the preamp via RCA cables.

I did not have the user manual so could not look it up. Just found a copy on the net and see that you are right. Thanks!

 

[sbfx]

Satyam , I just got a bit confused..in layman terms, is this how it is done ?
- Disconnect the Earth wire from the plug of all components except the preamp
-connect all the ground temrinals to the earth of the preaamp

Also, for Star wiring, is it enough to create a new distribution box which is star wired and connect all components to that ?

Arj, yes all you do is disconnect the earth of all other gear and just normally connect them, the earth to all other gear would be passed from the RCA cables itself from the preamp.

I reckon a new distribution box should also do the trick with star grounding!!


Regards,

Satyam Bachani.

 

[odyssey]

Arj, yes all you do is disconnect the earth of all other gear and just normally connect them, the earth to all other gear would be passed from the RCA cables itself from the preamp.

I reckon a new distribution box should also do the trick with star grounding!!


Regards,

Satyam Bachani.

Hi
Just so that everyone is clear - the earth being referred to in this post is signal ground, not the earthing in the power distribution. Its easy for someone to get confused between the difference between signal ground and the power earth at your home, perhaps we should refer to the signal ground as just 'ground' and the earthing ground as 'earthing'.
The ground loop - cause for hum is due to more than one path (loop) for the ground currents. Typically, the first thing to try is to connect all components on a single distribution strip from the same wall outlet (provided the power rating is not exceeded). If you think about it, this is also a "star" connection.
In the interest of safety, remove the chassis earthing is not recommended

cheers
Sridhar