I am building a tube preamplifier (phono, line stages) with four tubes per channel. Each stage is a separate "block" with star grounding to the reservoir capacitor of the common PSU.
The stages are interconnected with thin teflon coaxial cables. My question is: which end of the coax shield should be grounded to the ground of the actual stage? The source, the next stage, or both? I suspect grounding both end of the shield would cause a ground loop, and otherwise it is not necessary.
The stages are interconnected with thin teflon coaxial cables. My question is: which end of the coax shield should be grounded to the ground of the actual stage? The source, the next stage, or both? I suspect grounding both end of the shield would cause a ground loop, and otherwise it is not necessary.
The endless question. In practice it can depend. On factors and variables you dont know untill it is completely built. You can AC couple the shield in one end if DC currents flow due to voltage difference between gnds. Shields only protect against magnetic fields if they are gnd at both ends. Else the shield only works against capacitive coupled noise. But with only one end to gnd it will have a high frequency resonance which may or may not be a problem. For hifi mostly not a problem.
But internally you really should not have such potential differences between gnds. ?
Anyways. Best to try and see. I'd start with both ends to gnd.
But internally you really should not have such potential differences between gnds. ?
Anyways. Best to try and see. I'd start with both ends to gnd.