For an analog active crossover, I was thinking of using this ground layout.
I would ask if it makes sense to isolate the signal ground from the power ground, or being a circuit with low currents, is a single ground plane sufficient without isolating the signal ground?
Thanks for any support.
.
I would ask if it makes sense to isolate the signal ground from the power ground, or being a circuit with low currents, is a single ground plane sufficient without isolating the signal ground?
Thanks for any support.
.
It depends on your component layout. You have to consider the complete circuits, not just the current return paths. Look at the current loops and see how the current flows from start to finish. DC current will take the path of least resistance (shortest distance) while AC will follow the path of lowest impedance.
Minimizing loop areas is also a good goal. Loops act as antennae which transmit and receive noise. A ground plane in itself is no guarantee of good noise performance.
Minimizing loop areas is also a good goal. Loops act as antennae which transmit and receive noise. A ground plane in itself is no guarantee of good noise performance.
Here is the diagram and top view.
(NE5534 ompamps are just an example, there are output coils
instead of low value output resistors but I'm not sure it will improve the sonic performance)
In the left +12V, GND, -12V PSU in the right HP out, GND, LP out
(NE5534 ompamps are just an example, there are output coils
instead of low value output resistors but I'm not sure it will improve the sonic performance)
In the left +12V, GND, -12V PSU in the right HP out, GND, LP out
I changed the layout like this, the V+ decoupling capacitor should now be a little closer to the opamp. I had to insert some jumpers.
I don't understand if the ground that comes from the input in this context (line level, active cross) makes sense to keep it separate and then rejoin it at a single point (I've seen it done on several PCBs, however of the "final amplifier" type) or it is better to have a single ground plane.
Thanks for the help
I don't understand if the ground that comes from the input in this context (line level, active cross) makes sense to keep it separate and then rejoin it at a single point (I've seen it done on several PCBs, however of the "final amplifier" type) or it is better to have a single ground plane.
Thanks for the help
Personally, there are a couple of things that I would do. First, I would add decoupling capacitors where V+ and V- enter the board.
The other thing is more general, and it's just that I would do it this way. I would have kept the V+ and V- traces to each op amp close to each other rather than as separate loops. It may not make a huge difference in this case, but it would have been my approach. This would affect the ground plane, but that would be my choice.
I'm not a PCB layout expert, so I'm also open to thoughts on my ideas. I'm trying to get better at PCB layout as well.
The other thing is more general, and it's just that I would do it this way. I would have kept the V+ and V- traces to each op amp close to each other rather than as separate loops. It may not make a huge difference in this case, but it would have been my approach. This would affect the ground plane, but that would be my choice.
I'm not a PCB layout expert, so I'm also open to thoughts on my ideas. I'm trying to get better at PCB layout as well.
Solid ground plane is fully sufficient for line-level circuits like yours (crossover, it seems).
Use as much copper as you can on both sides of the PCB as GND and generously place vias to connect all the segments together. Vias come for free, so no problems to use many dozens or even hundreds. The goal is not to have any gaps in that combined GND plane.
Then the routing can also be simplifed in that the two layers have different dominant track orientations, like top mostly vertical and bottom mostly horizontal. Notably with THT components you already have access to the signal on both sides so that part is easy.
That said, you current layout is already good enough (when GNDA becomes GND and the bottom thus becomes a solid plane with no gaps, that is).
Please do not forget, the NE5534 is'nt unity-gain-stable! Put a comp-C between pin 5 and 8 of about 22 to 33 pF. Else you create an oscillator.
See tatasheet at ON or TI
See tatasheet at ON or TI
Yes, I know, I'm not sure if I use the NE5534 or others, but if I use it, for sure I add the compensation cap, maybe soldered directly under the PCB between the two pins 🙂
