The audio system does not need any connection to "Earth" to work. Think about all the portable audio equipment you carry about. None are connected to "Earth" and they all work till some crap inside fails.
The mains powered equipment that we build needs to be safe to operate.
It's that SAFETY of mains powered equipment that must be addressed.
Rule 1.
The enclosure must be permanently and mechanically connected to the Protective Earth (PE) wire.
Rule 2.
All exposed conductive parts should be connected to the protected chassis/enclosure.
The first (PE) is easy and most Builders seem to recognise it's need and how to achieve it. But we still get a few Members that think they can design and build and test and guarantee ClassII Double Insulated equipment, without any training in those specialised areas.
It's Rule 2 that causes confusion.
It is a SAFETY rule, it has NOTHING to do with getting the audio side to work.
The purpose of Rule 2 is to protect a user from touchig a LIVE part of the equipment after an internal failure.
To work effectively one must examine one's proposed build and work out which external conductive parts could be touched. Then work out how to connect them to the protected chassis.
I find the easiest way is to make a safety connection from the Main Audio ground (MAG) to Chassis/enclosure.
That's the green wire pointing to the chassis in Mark's post17. It's way over on the right.
The mains powered equipment that we build needs to be safe to operate.
It's that SAFETY of mains powered equipment that must be addressed.
Rule 1.
The enclosure must be permanently and mechanically connected to the Protective Earth (PE) wire.
Rule 2.
All exposed conductive parts should be connected to the protected chassis/enclosure.
The first (PE) is easy and most Builders seem to recognise it's need and how to achieve it. But we still get a few Members that think they can design and build and test and guarantee ClassII Double Insulated equipment, without any training in those specialised areas.
It's Rule 2 that causes confusion.
It is a SAFETY rule, it has NOTHING to do with getting the audio side to work.
The purpose of Rule 2 is to protect a user from touchig a LIVE part of the equipment after an internal failure.
To work effectively one must examine one's proposed build and work out which external conductive parts could be touched. Then work out how to connect them to the protected chassis.
I find the easiest way is to make a safety connection from the Main Audio ground (MAG) to Chassis/enclosure.
That's the green wire pointing to the chassis in Mark's post17. It's way over on the right.
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D.Self chooses to show the Safety connection from MAG to Chassis at the signal input socket on some of his drawings.
If you choose to copy this advice then you MUST ensure that the route that FAULT Current takes to pass along the various wires can survive long enough till the mains fuse ruptures and the arc extinguishes. That is an onerous task for a signal connection.
Are you able to test your Safety connection for that FAULT current incident?
If you choose to copy this advice then you MUST ensure that the route that FAULT Current takes to pass along the various wires can survive long enough till the mains fuse ruptures and the arc extinguishes. That is an onerous task for a signal connection.
Are you able to test your Safety connection for that FAULT current incident?
Connecting the MAG to the chassis at or near the PE connection ALSO gives maximum immunity from ground loops. Is this wrong? This is why I am querying the PDF file at post 11.
Yes, I think this is wrong. You can use the chassis to connect the PE grounds together, which I think is better than having PE wires running alongside other wires/circuits, increasing ground loop problems. Best is to move the boards closer to the PE.
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A simple rule :
For RF protection, coaxial cable outer conductor must be connected to chassis.
( http://www.diyaudio.com/forums/cons...-mounting-rca-jack-chassis-3.html#post4933868 )
More info... with measurements :
http://www.diyaudio.com/forums/anal...nal-grounds-chassis-vs-pcb-5.html#post4764949 , posts #89, #90, #91, #92.
Conclusion, post #94 :
Currenty, more than two monthes later, the above measurements have not been commented at all. Very disappointing.
The location of the Safety connection from MAG to Chassis has no influence on the interference currents that flow around the audio circuits.
If there is a loop that passes interference current around an audio circuit then whether the MAG to Chassis connection is beside or on ar far away from the PE makes no difference to the existence of the LOOP.
Remember I said "It's Rule 2 that causes confusion.
It is a SAFETY rule, it has NOTHING to do with getting the audio side to work."
Moving the connection point to one, or other location, on the Chassis/enclosure makes no difference to the existence of the LOOP.
The Bonsai quote that states the PE and MAG to Chassis MUST be the same point/location is wrong. It is not a necessary condition. It does not solve a loop problem.
The signal return needs to be referenced to the speaker return. It's just a grown up opamp. The voltage reference for the input and output is treated exactly the same.
But overriding this is the requirement to use a two wire/trace pair for the signal current to pass around and use a two wire connection for the speaker current to pass around. Get those installed as a close coupled pair first, then see if a voltage reference between IN and OUT is required. Many opamp and amplifier PCBs have this reference connection on the PCB.
Those measurements and the conclusions drawn from them were commented on.
But the Member would not complete the measurment set to include the other suggested layouts.
He would ONLY publish data for the two extremes, neither of which mimic the way amplifiers are actually assembled.
Yes. But are you saying the signal return does not have to be referenced to an earthed (as in the thing we live on) chassis? Or maybe it's referenced somewhere else, I don't know, I'm asking. Or maybe I'm wrong using the term signal return?
Where ?
Have you provided measurement proving that your suggested layouts are better than those suggested by the Member and which he has experimented a lot ?
in his Thread.
No, I don't have the expertise, nor the equipment to generate those type of measurements/results.
We did not say there are better. We asked him to investigate alternatives between his two extremes.
Ok folks I've got another question.
I'm going to use a input selector with PGA2311 board.
There will be four stereo input (only one active), ofc that board will use relays for signal switching.
But lets assume that I will connect four stereo devices, so let's name them as a :
A
B
C
D
There will be only one active due to relay configuration, but even then all RCA sockets will share same, common signal ground.
Does it good? I think it's kinda strange.
I'm going to use a input selector with PGA2311 board.
There will be four stereo input (only one active), ofc that board will use relays for signal switching.
But lets assume that I will connect four stereo devices, so let's name them as a :
A
B
C
D
There will be only one active due to relay configuration, but even then all RCA sockets will share same, common signal ground.
Does it good? I think it's kinda strange.
@Scott you're very active user 🙂
But how about isolating each input ground (so there will be four grounds) using a resistor with main ground?
I hope you understand what I'm talking about.
But how about isolating each input ground (so there will be four grounds) using a resistor with main ground?
I hope you understand what I'm talking about.
I get around! Sometimes a small resistor, usually less than 10ohms is used but generally only if there is a problem with ground loops. This might help High Quality Audio Preamp
I was thinking about something like this :
PIC1 (most common option I supose) :
PIC2 (maybe some kind of alternative - just an idea) :
PIC1 (most common option I supose) :
PIC2 (maybe some kind of alternative - just an idea) :
Relays are a good idea for signal switching, some good examples of how to do that on the ESP pages I linked you to above as well. I can find them for you if you are having problems navigating the site, it is quite extensive.
I don't know what to do with the diagram you've posted above to be honest 😀.
Do you understand simple circuit diagrams like that one for switching the inputs in the link I gave you?
I don't know what to do with the diagram you've posted above to be honest 😀.
Do you understand simple circuit diagrams like that one for switching the inputs in the link I gave you?
I know how to build simple input switcher 😉
It's about that common ground for all rca sockets, even when they're not in use but with connected devices.
It's about that common ground for all rca sockets, even when they're not in use but with connected devices.
I see. It's not an issue they are connected to the input signal ground/return (whatever you want to call it) all together and not switched
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