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Tying it all together - Low Noise Internal System Grounding
Tying it all together - Low Noise Internal System Grounding
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Old 21st August 2011, 02:14 PM   #1
Zero Cool is offline Zero Cool  United States
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Default Tying it all together - Low Noise Internal System Grounding

I was once told, in life as well as electronics All things must return to ground! I guess that is true!

Grounding in electronics is something I have always struggled with. The concept of "all grounds should return to a central low impedance point" makes sense in theory. but in practice that seems to be a little harder to understand. especially when trying to avoid ground loops.

Looking at how other manufacturers do it, it seems there are a million ways to do it right and wrong!

and then factor in analog AND digital in one chassis and things get messy real real fast!

I have put together a simplified drawing of the DAC project I am working on. and i hope to have some open frank discussions about how all these grounds should be tied together for lowest noise. and I'm hoping that through these discussions that others will find some of the information beneficial when it comes time to wire up there own projects! I mean that IS the reason we are all here correct??

So lets take a look at my example project drawing. here we have a whole bunch of this and that, that all needs to be tied together somehow.

Starting at the top and working down we first have the bipolar power supply for the analog buffer stage. Now if this was a preamp and this was all there was to it i would simply tie the power supply to chassis ground through a 10ohm resistor and be done with it. However...

Next we add a whole bunch of digital stuff!

Four power supplies to feed the two DAC boards. each board has its own power input for the Analog and Digital side of the DAC chips.

Then we add a Micro controller, in this case an Arduino board that will control power and input selection etc etc.

and we have a 5 Volt supply that will control all of the 5v digital stuff such as the I2S switch board, CS8416 4:1 Mux board and the USB Receiver device.

and lastly we have a 12volt supply that will feed all the misc system control stuff like relays and LED's etc etc.

So how do we tie all of that together and return back to chassis ground for the lowest possible noise floor??

Are there parts of this that SHOULDN'T be tied back to chassis?

Should each supply be tied together through some low value resistor? say 1ohm between each supply? or??

Please help me to understand how system grounding as such should be done on through a whole systems approach??

Zc
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Old 22nd August 2011, 04:03 AM   #2
Zero Cool is offline Zero Cool  United States
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No takers??
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Old 22nd August 2011, 06:03 AM   #3
Pano is offline Pano  United States
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Tying it all together - Low Noise Internal System Grounding
You did read this, right?
Audio Component Grounding and Interconnection
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Old 22nd August 2011, 12:20 PM   #4
Zero Cool is offline Zero Cool  United States
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No but I have now! and i guess it addresses some issues. but I don't think it goes into detail enough about the differences between digital grounds and analog grounds. but i quickly skimmed over the article. I will read it more in depth this evening.


Zc
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Old 23rd August 2011, 07:46 AM   #5
metalsculptor is offline metalsculptor  Australia
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Digital grounds are kept separate to analogue grounds except at the the point of interconnection. This is to keep the voltage spikes caused by the fast rise time charging pulses that are part of digital systems out of the analogue system. Good design practice also keeps the lines carrying these fast rise time signals away from the signal carrying lines.

Instrumentation literature covers this in detail, look up some of the application notes from burr brown (texas intruments) and analog devices
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