mshilarious wrote:
> Typically, pin 1 is tied directly to the preamp case at the input connector.
That would be the best practice by far for RF immunity, but many portable preamps and recorders (especially, but not exclusively, made in the Far East) seem not to follow it. I've seen an awful lot of gear that has its input and output connectors soldered directly to the main printed circuit board; those connectors then fit through holes in the case. If the equipment has a metal case and there's any connection between it and the circuit board's ground, often that connection is made through mounting parts such as screws or posts that touch ground traces on the PCB.
Basically, it's an invitation for induced shield currents (buzzy hum) to come right on in and get amplified, so it's way more important than what your cables are or aren't made of (that last statement won't help me win any popularity contests in this section of the forum, I realize).
--best regards