Thank you for all of the kind comments. I am pleased that so many are receiving benefit from the article. Let me respond to a few of the comments.

Alan (waltzingbear) Good point on the panel and I will clarify that in a future update. Many knowledgeable engineers (some referenced in the article) object to switching power supplies, not because they can't be done well, but rather, because they haven't been done well in a lot of consumer equipment.

Omega_Void The point of that section is to say which ground each transformer frame should be connected to so noise is not introduced into another ground. You would definitely not want to connect the transformer frame to neutral.

Dave (zdavesf) You might have an easier time printing the version of the article on my website, which is a pdf. It is at https://www.raleighaudio.com/Audio%20...connection.pdf

Hi Fi Nut Nut I Have seen that back to back diode scheme used several places. I think (although I am not sure) that this scheme is not in compliance with the standards. I am not going to second-guess the standards so I don't even mention that scheme. However, I will say that in general, I believe all ground isolation schemes to be band-aids and should not be needed in a system with properly designed grounding.

Dave

Hi,

What an excellent article. Full of valuable informations. Thanks a lot.

One thing still puzzles me. Legal or not, isolating the chassis from the earth with a 600V 35A bridge wiring up the diodes in both ways would solve many of the problems without compromise of safety and without the inherent problems of a loopbreaker. The idea is so simple but why nobody has recommended it?

@HiFiNutNut
If you are using the term "earth" to refer to the safety ground, it would be illegal to isoloate it from the chassis. The safety ground or "earth" must be bonded to the chassis close to its entrance into the chassis. This make perfect sense.

If you are using the term "earth" to refer to the signal ground reference point, then isolating it from the earthed chassis would degrade, so to speak, the shielding of the components, since it is said by the experts quoted in the article that for best shielding, the signal ground reference should be at the same potential as the shield (chassis).

Thanks Dave for outing the sources for the desirablility that the chassis and signal grounds should tied together for best shielding. I've been saying this in several posts, but didn't make any effort to dig through Morrison, Ott, etc., to get the support for this. I agree with Dave that the ground isolation is a crutch to less than ideal grounding schemes. Of course, if you are one of those that insists that shielding makes for inferior audio reproduction, ....

Well, I figured a way to modify the pictures by hosting them on my own site rather than the diyAudio site. However I hope this is not a permanent solution because if my site ever went away ....

Dave

Avoiding ground loops are important when dealing with audio line signals of 100mv against the capacity safety coupling which produces half the mains potential. One way to avoid ground loops is to use magnetic coupling as described in the splendid article. This product is using this technique for isolating USB devices - USB 2.0 Isolator - Isolated USB

The rectified mains idea is a killer. If the ground wire fails everything is at sqrt(2)*mains voltage - very dangerous. Futhermore diodes makes a lot of noise when they turn on/off - typically at 0.3-0.7 forward voltage. There will also be a voltage difference over the diode (the forward voltage). - So connecting to another device would draw real current in the data/signal wires. So thats why it is not done via a diode bridge solution.

I have developed the USB2ISO module to isolate a PC from USB devices like a USB soundcard to avoid ground loops. Works great for USB devices.