Layer stack-up consideration for two-Layer PCB

I’m working on a two-layer PCB layout for an analog audio application. The board is relatively large (around 18cm x 12cm) and uses through-hole components. The design requires a dual power supply. Given these considerations, which of the following layer assignments would be the most suitable for routing signals, power, and ground?

Options:

  1. Top layer: Ground plane and power supply tracks; Bottom layer: Signals

  2. Top layer: Signals; Bottom layer: Ground plane and power supply tracks

  3. Top layer: Ground plane; Bottom layer: Signals and power supply tracks

  4. Top layer: Signals and power supply tracks; Bottom layer: Ground plane

I’m looking for insights on the best practice for separating analog signals, power, and ground in a dual-supply audio circuit, considering factors like noise coupling, return paths, and ease of routing. Your advice will help me make an informed decision on the layer stack-up for this design.

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Why does it matter?

I think the general rule is that it is better to route (break up into traces, rather than having a full plane) power than ground, so that would suggest 3 or 4, but … If you ever need to cross tracks over each other, you’ll have to either use a “0-ohm resistor” or other wire … or send stuff to the “wrong” side.

With through-hole devices, you’re not even breaking one side up more than the other.

Maybe some components would be happier with their body by a ground plane? Maybe the ground plane on the other side will provide some shielding?

If you experiment and it turns out to matter, please do report back.

I believe through-hole designs and 2-layer boards are perfectly valid options in many situations.

For most cases, I recommend using a ground plane and a signal/power plane. This approach is well-established and reliable, and there’s no strong reason to avoid it. The placement of the signals on either side isn’t critically important.

You might need to create some jumpers in the ground plane, but this shouldn’t pose any issues as long as you avoid making large cuts.

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