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Old 21st April 2010, 12:00 PM  
David Davenport is offline David Davenport  United States
diyAudio Member
Join Date: Jun 2004
Location: Raleigh North Carolina
Default Audio Component Grounding and Interconnection

This article focuses on audio system design for the DIY enthusiast implementing a stereo system for home use. There is a lot of information available for designing audio circuits, but precious little on interconnecting those circuits into a total audio system to achieve maximum performance....

Last edited by Variac; 2nd April 2011 at 12:07 AM.
23rd April 2010
David Davenport
diyAudio Member
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.

28th April 2010
diyAudio Member
An excellant article 10/10, a clear and consise synopsis of "grounding" issues, and references to EMC and the problems it causes. (I am a
strong supporter for banning data over powerlines etc.)
It would be interesting to take this further and discuss the various grounding schemes available for various PCB designs,
analogue, digital and mixed, and discuss thier advantages and disadvantages, and how EMC is becoming more of a problem and how it can combatted
and also avoid creating more EMC problems.
This is becoming more important IMO as more digital based electronics is becoming the norm in Audio repreduction, whether it is a SMPS, ADC/DAC, class D
etc, so things are becoming dirtier (electronicly) and PCB layout is becoming more critical, and allPCB's should be laid out from the ground up as it is the most important signal.
29th April 2010
binspaul's Avatar
diyAudio Member

What an excellent article. Full of valuable informations. Thanks a lot.
30th April 2010
juma's Avatar
diyAudio Member
Thanks for the great article

BTW, there is a picture missing at:
Figure 3.5-4, Balanced to single-ended interconnection.
30th April 2010
diyAudio Member
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?

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, ....
30th April 2010
David Davenport
diyAudio Member
Yes, there is a picture missing and a few pictures that need the be updated but I haven't found out how to edit the pictures yet.

30th April 2010
David Davenport
diyAudio Member
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 ....

6th May 2010
dave w p
diyAudio Member
Don't forget when using star earths the ideal is to use a single earth point, also avoid duplication of earthing. This is not always practical but must always be aspired to.
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29th May 2010
diyAudio Member
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.
29th September 2010
diyAudio Member
Kudos Mr. Davenport


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