[sdiy] How to design out "usb noise"?

[cheater cheater]

On Sat, Feb 3, 2024 at 2:35 PM Mike Bryant <mbryant at futurehorizons.com> wrote:
>
> Agreed.  I've got PCBs with a RaspberryPi CM4 running at 1.8GHz, a couple of other processors running at 200MHz, switchmode regulators, USB and MIDI connectors, then a PCM5102 DAC and balanced analogue output stages and all the various sockets (some on the backside) all on a PCB 100mm * 100mm.  It's how you do the grounding that matters, very little else.
>
> In fact the prototype used 2 layers as well, but now 4 layers are so cheap at JLCPCB just go straight to that - makes life so much easier :-)

Obviously you can have audio running noiselessly on a digital board as
evidenced by the fact that all our music comes out of some digital box
nowadays. But that's for people who know what they're doing and don't
need to ask basic questions on sdiy, as evidenced by decades of shitty
motherboard audio outputs.

> ________________________________
> From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Mattias Rickardsson <mr at analogue.org>
> Sent: 03 February 2024 13:18
> To: cheater cheater <cheater00social at gmail.com>
> Cc: Synth DIY <synth-diy at synth-diy.org>
> Subject: Re: [sdiy] How to design out "usb noise"?
>
> Den lör 3 feb. 2024 12:32cheater cheater <cheater00social at gmail.com> skrev:
>
> it makes sense to put the digital stuff on a separate pcb that's at
> least 1cm away from the analog stuff. (or at least, strip off a huge
> chunk of copper between them). This to prevent capacitive coupling.
>
>
> It's the grounds that need to be galvanically isolated. Signals disturbing signals are not the issue here afaik.
>
> /mr