Chassis earth and ground

[Koonw]

I'm not sure I'm catching the drift here. Maybe you are saying that in a specific example, a particular grounding scheme you adopted turned out to work well? That could certainly be true; there are so many factors at play that trying to extract general principles based on specific anecdotal examples is not necessarily easy or useful.

Chris

I didn't adopted a particular scheme in particular the 1 ohm resistor, it comes from my own practical work! Then later you find someone has done the same thing, what say you? There is no prior knowledge of the wonderful articles I referred or linked to as I already complete my work before I read them, so there nothing to be added other than through my research. Thank you. Unfortunately we don't each other well before I comment further. Maybe you can comment further what do you actually mean??

 

[AndrewT]

The basic problem trying to be addressed by all these posts is the misuse of the term "ground".

Forget about "ground".

Instead, think about the current route.
The current MUST flow around a loop. It MUST return to the SOURCE.
This requires every connection to have two wires/traces. A Flow trace from the Source to the Receiver and a Return trace from the Receiver to the Source.

The intent here should be to reduce the effects of interference on the current loop.

The best tool for us to reduce that interference is LOW LOOP AREA.
That's why I said back in post31

This pdf shows how to identify the current loops and how to arrange these loops so that they don't interfere with each other.

I never mentioned "ground". It does not need to be considered.

Get each and all connections made with low LOOP AREA, using a two wire connection for each ROUTE.
Then look at the whole amplifier and determine if there are any single wire connections that need to be added to allow voltage references to be linked together.

Resolve the current routes FIRST !

 

[AndrewT]

"I may even use the chassis as the ground bus.
But many people will disagree, there is no consensus about ground schemes and I am not going to claim that I hold the ultimate truth."

In some countries ground lift of any sort is not acceptable, so you have to design one without it. That is good you can do it. Interconnect plays an important part too. maybe all the use of ground lift is get rid of hum introduced by interconnect screen rather than the actual signal ground loop.

Protective Earth (PE) and the Chassis have nothing to do with the audio circuit.
The audio circuit will work without a chassis and without a PE.

But for our Safety we require to protect ourselves and our loved ones from the dangers of using Mains powered equipment.

Don't mix up safety requirements with audio requirements.

Get the audio working with the right arrangements for best performance.

Then build it with the required safety designed in to minimise the chassis' effect on the audio. Yes the chassis does affect the audio. I have NEVER managed to build a completed chassis enclosed power amplifier that performs better than the uncased prototype strung out along the bench.

 

[Koonw]

Protective Earth (PE) and the Chassis have nothing to do with the audio circuit.
The audio circuit will work without a chassis and without a PE.

But for our Safety we require to protect ourselves and our loved ones from the dangers of using Mains powered equipment.

Don't mix up safety requirements with audio requirements.

Get the audio working with the right arrangements for best performance.

Then build it with the required safety designed in to minimise the chassis' effect on the audio. Yes the chassis does affect the audio. I have NEVER managed to build a completed chassis enclosed power amplifier that performs better than the uncased prototype strung out along the bench.

Of course, everyone knows the difference between a battery powered and mains operated radio, in the later its the hum that bother you. Everyone is trying eliminated it since it interferes with audio video equipment. This is called interference, much like RF interference from transmitter, static from thunderstorm. Some receivers have big diode shunt the input, it has nothing to do with audio, but the equipment would just fail just without it. It also example of a safety issue nothing to doing with audio. There are so many components that dim necessary earlier have been quietly eliminated by today minimalist design who not maybe even has the minimal safety requirement including proper ground so it classified into several Classes of equipment they have no earth yet consider safe. you just can't connect to chassis of a TV with your audio equipment for example. A lot of audio issues arise when connecting earthed and no earthed audio equipment, no to say it nothing to do with each other, the audio quality already suffers without one even realized it.

"Get the audio working with the right arrangements for best performance."

I think you only know too well how easy or how difficult it is. In my view you should consider all issues at once if possible to avoid any pitfall when actually connected, if you're really serious about it, unless it never need to work together, just standalone or mobile i.e. why do you have noises when you want to hook your HP or computer audio to tube amp?? If you plan to use this way you would have already included an audio isolation transformer or purchase a sound card with similar transformer. Most people don't know what to do or simply know to well the audio quality suffer even more with lot of addition. Is Class D amp the solution? The sources input become an issue nowadays.