[sdiy] Eurorack Grounding Question

[Roman Sowa]

My opinion about mindless automatic groundfill put everywhere is similar 
to what many others think about 100% blind recapping. With ground fill 
you have no control over return currents or ground currents whatever you 
call them. Sometimes I see ground fill made on PCBs in such pointless 
ways that captain Picard is facepalming in front of me even without 
closing my eyes.

In short, make separate groundfills for areas where you woudn't like to 
mix the signal, like mic preamp and stage light driver nearby. And link 
them only at the ground star point (which is not always possible, as in 
eurorack the ground star point is far away outside the module). But if 
you really need to have one, connect it to the "shield" ground that was 
talked over already in this subject. Obviously such groundfill should 
not link to any of the "real" signal ground traces anywhere

Ad.2 - DAC is analog component and should be treated as opamps and other 
sensitive audio circuit.

Roman

W dniu 2020-12-31 o 09:01, Steven Cook via Synth-diy pisze:
> Thank you for these answers. I think I'll go with Tony's recommendation. 
> The reason I have input jacks connected to the digital ground is simply 
> that they are connected to the microcontroller (via transistors and 
> reverse voltage protection diodes), so I assumed that the jacks should 
> be also - I'll change that.
> 
> I have a couple of follow-up questions:
> 
> 1. If I have a ground fill on the PCBs, which ground should it be 
> connected to?
> 
> 2. Which ground should the DAC be connected to?
> 
> ------ Original Message ------
> From: "Steven Cook via Synth-diy" <synth-diy at synth-diy.org>
> To: Synth-diy at synth-diy.org
> Sent: 29/12/2020 09:30:46
> Subject: [sdiy] Eurorack Grounding Question
> 
>> Hi, I'm designing a Eurorack module which uses a microcontroller. The 
>> PCB has separate analogue and digital grounds joined at the power 
>> input header, but I've realised since designing it that both grounds 
>> will also be shorted together by the front panel as there are input 
>> jacks connected to the digital ground and output jacks connected to 
>> the analogue ground. I assume this would create an ground loop. Would 
>> I be better off not bothering with separate grounds?
>>
>> Regards,
>>
>> Steven Cook
>>
>>
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