I am in a process of installing a SSL AWS900 console on which there's an specific thicker ground screw on the rear.
My doudbt is: the console manual says"All analogue inputs and outputs can be conected via patchbay. It is recommended tha the cable shield is conected at the console end and disconected at the patchrow to avoid ground loops. The shield conection of all jacks should be link together and then linked to a comom star point on the patchbay. This star point can be returned to the chassis stud on the rear of the AWS 900+". Is it true, how does it work, can you explain it better to me?
Cable shield at console and disconected at patch?
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Hi,
from what I read, this star grounding functions as follows:
Cable shields are grounded to the desks star point, then patchbay jack shields and chassis are grounded to a central patchbay starpoint that will be connected to the desks main starpoint as well.
This is quite a good solution that should avoid the groundloop that can apply if both sides of the cable / multicore are connected to shield.
(Desk-cable shield-patchbay-Mains ground - Desk... - GROUNDLOOP)
Note, that you actually CAN connect shield on both sides on special occasion without hassle IF transformers are involved or potential difference is minimal - e.g. short cabling ways, very good mains earthing etc..
I doubt it makes a difference which side of the cable is disconnected from shield actually, but in case of doubt (if you are not aware of proper shielding/grounding/earthing in the patchbay!) the desk should nearly always be trusted as a good grounded starpoint.
(If the desk has a problem with grounding generally, this should be resolved first anyway!)
Therefore they recommend the way they did it.
Please note - this recommendation is no way overdozed!
Shield disconnection on one side can be considered a good (if not best) practice against ground loop buzz hum and noises in general.
I consider this not as a gimmick but as essential...
Kind regards,
Martin
from what I read, this star grounding functions as follows:
Cable shields are grounded to the desks star point, then patchbay jack shields and chassis are grounded to a central patchbay starpoint that will be connected to the desks main starpoint as well.
This is quite a good solution that should avoid the groundloop that can apply if both sides of the cable / multicore are connected to shield.
(Desk-cable shield-patchbay-Mains ground - Desk... - GROUNDLOOP)
Note, that you actually CAN connect shield on both sides on special occasion without hassle IF transformers are involved or potential difference is minimal - e.g. short cabling ways, very good mains earthing etc..
I doubt it makes a difference which side of the cable is disconnected from shield actually, but in case of doubt (if you are not aware of proper shielding/grounding/earthing in the patchbay!) the desk should nearly always be trusted as a good grounded starpoint.
(If the desk has a problem with grounding generally, this should be resolved first anyway!)
Therefore they recommend the way they did it.
Please note - this recommendation is no way overdozed!
Shield disconnection on one side can be considered a good (if not best) practice against ground loop buzz hum and noises in general.
I consider this not as a gimmick but as essential...
Kind regards,
Martin