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Old 28th November 2012, 10:30 PM   #1
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Default Are ground planes in audio pcbs legit?

I haven't looked at many audio amplifier pcbs but it seems almost none of them use ground planes. Are they typically a bad idea in audio amplifiers? It would definitely make routing a lot easier with them.
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Old 28th November 2012, 10:31 PM   #2
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Also, what about line level pcbs (active filters, etc).
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Old 28th November 2012, 11:50 PM   #3
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There is nothing wrong with using ground-planes in audio circuits (in a way the metal chassis is one), but you must take care that you seperare (physically and electrically) your digital from analogue circuitry
I rarely use ground/supply planes unless I work with high gain and/or high frequency stuff. E
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Old 29th November 2012, 12:06 AM   #4
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Quote:
Originally Posted by mickeymoose View Post
There is nothing wrong with using ground-planes in audio circuits (in a way the metal chassis is one), but you must take care that you seperare (physically and electrically) your digital from analogue circuitry
I rarely use ground/supply planes unless I work with high gain and/or high frequency stuff. E
I'm talking pure analog audio amps and line level filters, no dacs. And this will potentially be without a metal chassis, just ground pcb plane.
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Old 29th November 2012, 12:10 AM   #5
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To achive the lowest distortion, noise and hum, audio amplifiers general use carefully designed PCB trace routing, to eliminate loops and contaminating currents (such as output stage currents in the 0V rail passing through 0V rail for the input stage).
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Old 29th November 2012, 12:21 AM   #6
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The biggest problems are caused by poor grounding and ground loops.
My first audio mixer hummed like mad coz I just laid the pcb out as it came.
The pulses of current into the smoothing capacitors were also getting into the audio ground. I completely separated the power supply and audio grounds and the hum completely disappeared.
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Old 29th November 2012, 12:26 AM   #7
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Originally Posted by glennb View Post
To achive the lowest distortion, noise and hum, audio amplifiers general use carefully designed PCB trace routing, to eliminate loops and contaminating currents (such as output stage currents in the 0V rail passing through 0V rail for the input stage).
I understand that, but that doesn't really help answer my question. Is it impossible to achieve low noise and hum with a ground plane?
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Old 29th November 2012, 12:28 AM   #8
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Originally Posted by nigelwright7557 View Post
The biggest problems are caused by poor grounding and ground loops.
My first audio mixer hummed like mad coz I just laid the pcb out as it came.
The pulses of current into the smoothing capacitors were also getting into the audio ground. I completely separated the power supply and audio grounds and the hum completely disappeared.
My power supply is on a completely different board than my amp and other circuitry.
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Old 29th November 2012, 12:36 AM   #9
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Originally Posted by Fusion916 View Post
I understand that, but that doesn't really help answer my question. Is it impossible to achieve low noise and hum with a ground plane?
Depending how you connect your ground line to the ground plane you could make it worse.

I would lay out the pcb as per my previous post then use separate power plane for power and audio ground and star ground them in one place.
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Old 29th November 2012, 12:42 AM   #10
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I believe your question was anwered. You do not need a ground-plane, just good design technique to get clean amplification. E
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