Hi all,
I'm in the midst of designing my first pcb-based tube amp. I'm not going with a ground plane, rather I'm simply adapting my usual multi-star / bus approach to a pcb.
However, I have read that a grounded copper pour can provide some shielding and help prevent crosstalk in nearby traces. Is there any benefit, or perhaps more importantly, any drawback to adding a ground pour on one or both layers of the pcb, but connecting it to the chassis?
In other words, although I'm using a traditional scheme with separate ground traces, I'm considering adding a ground pour to the pcb to serve simply as shielding. This pour would NOT be a ground plane as it would carry no signals and not be connected to the circuit. It would simply serve as an extension of the chassis, connected through the plated screw holes of the pcb.
Any reason not to do this? Is there any potential benefit or drawbacks?
I'm in the midst of designing my first pcb-based tube amp. I'm not going with a ground plane, rather I'm simply adapting my usual multi-star / bus approach to a pcb.
However, I have read that a grounded copper pour can provide some shielding and help prevent crosstalk in nearby traces. Is there any benefit, or perhaps more importantly, any drawback to adding a ground pour on one or both layers of the pcb, but connecting it to the chassis?
In other words, although I'm using a traditional scheme with separate ground traces, I'm considering adding a ground pour to the pcb to serve simply as shielding. This pour would NOT be a ground plane as it would carry no signals and not be connected to the circuit. It would simply serve as an extension of the chassis, connected through the plated screw holes of the pcb.
Any reason not to do this? Is there any potential benefit or drawbacks?
I think the way you intend to connect the pour is a sensible one and I have done similar with good results.
There is one thing to watch out for: depending on the topology, you may introduce additional (parasitic) capacitance to nodes in the circuit, which may impact performance. Keep it away especially from high impedance nodes in tube circuits.
In a worst case it could lead to premature freq response roll-off and even instability. Try to avoid stray capacitance at high-impedance nodes.
Other than that, its a good idea.
Jan
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