signal earthing/ground scheme

[ruffrecords]

Hi Ian,

I am using your Phantom circuit together with the jensen standard mic input scheme , i.e. with the 220Uf cap and a 220R resistor at the switch.
http://www.jensen-transformers.com/as/as016.pdf

I have a dedicated toroid supplying the PSU board which has linked 2x25v windings for 50v into the board.

I am not deriving my phantom power from the main TX secondary.

all my XLR pin 1's are now connected straight to chassis.  I didn't realise at first but the insulated Neutrik combo jacks have a really neat way of doing this via a couple of sharp pointed ground connectors which dig into the faceplate when you tighten the socket in place.

Cheers
Pete

OK, your system is in good shape, so you should follow the advice under Avoiding Hum #1 and use the second method of connecting 0V phantom power direct to the XLR pins 1. Also follow the advice on wiring up the phantom on/off switch.

Cheers

Ian

 

[PeteC]

Great

many thanks Ian
I will follow your advice.
Rgds
PeteC

 

[tubegeek]

Two documents in Rane's Pro Audio reference library (http://www.rane.com/library.html) might be interesting:

Grounding and Shielding Audio Devices: http://www.rane.com/note151.html
Pin 1 Revisited: http://www.rane.com/note165.html

Rane redesigned their entire product line years ago in order to adopt best practices regarding shielding and grounding, and they have several more articles that take the subject even further if you are interested.