Which GNDS option do you like better?

[BluegrassDan]

Which do you think is better?

Option 1: Separate preamp channel PCBs, with GNDS connected by wire.
Option 2: Both channels on a single PCB, with GNDS connected by small pour section
Option 3: (Not shown). GNDS pour on the WHOLE THING!

Mostly interested from a layout/noise perspective. There are various pros and cons to both scenarios in other regards.






Thanks in advance!

 

[merlin]

Option 1 & 2 are both good. Just depends if it is convenient for you to have two smaller, identical PCBs made, or one big one.

 

[abbey road d enfer]

Option 3 is not recommended, because of the risks of contamination between stages.
More generally, ground pours must be organized in a way that prevents ground currents to interact. A ground pour that connects indiscriminately output and input stage is not good; moreover a ground pour that connects indiscriminately PSU ground and circuit grounds is a receipe for disaster.
A ground pour must be designed to emulate the wires that one would use to interconnect.

When laying out a stereo/dual unit, remember that they will be connected at the PSU. Think of what happens when the connections to the outside world are sharing a common ground.

 

[JohnRoberts]

+1 to Abbey's comments. Try to visualize the current flows.

I find it helps to think of local signal grounds as 0V nodes. There can and will be multiple 0V nodes within a design.

JR

 

[john12ax7]

For multi channel units separate duplicate pcbs is often the easiest effective solution. Don't make one big pcb unless you have a good reason to.

 

[JohnRoberts]

For multi channel units separate duplicate pcbs is often the easiest effective solution. Don't make one big pcb unless you have a good reason to.

Depending on the complexity of the product using multiple small boards is easier on the PCB layout artist, but all those separate PCB need to be connected to common power supplies involving multiple connections and points of failure/mis-assembly. Using a single PCB reduces manufacturing cost.

Of course for one-off DIY projects buying multiple small boards is typically cheaper than sourcing only one large PCB.

JR

 

[ccaudle]

all those separate PCB need to be connected

And mounted. Having single channel PCBs takes up a lot more physical space since now you have screw holes on each PCB, possibly larger gap between channels, etc.

Separate preamp channel PCBs, with GNDS connected by wire.

There is an option you did not show, which is power and gnd wires twisted together for each channel, and only join at the external power supply entrance.

 

[JohnRoberts]

I have used both approaches depending on the complexity of the SKU.

In large consoles we use separate channel PCBs for each strip. Small (value) mixers routinely use a single PCB (Peavey even had pots and jacks tooled up special to work together on single level PCBs).

I did one 4 track cassette deck using separate per channel boards that plugged into a front panel mother board, with the channel boards tilted at roughly a 45' angle, for better access to per channel trims, for alignment. The tape deck had lots going on under the hood.

JR