I am getting ready to start wiring some patchbays. I realize this is a painstakingly time consuming endeavor, and I want to make sure I do it right the first time.

My questions is regarding the "sleeve" contact on the jack, or the ground. Should I lead every sleeve contact to a common point, so that all of my gear shares a common ground, or should I keep them isolated from eachother? If I do pick one common ground point, can I just jumper all of the ground terminals to eachother? How should I wire mic lines? Should all of my patchbays share one common ground?

Any tips or advice are appreciated in advance.

mike

hey mike
The best way to do this I've found is to not use the patchbay for anything but straight connection. That is connecting hot, cold, and shield of all pairs to their patch point. Leave all the ground-lifting to the connectors going to the given equipment.
As far as avoiding ground loops, a good rule to follow is lifting the shield at the input connector on all the equipment (other than mic inputs). This way, the output of the previous device will take care of grounding the shield. There would be no connection between unit A's and unit B's grounds, eliminating the possibility of a ground loop.
If for some reason your patchbay has no isolation between shield connections (like some phone patchbays), your kinda screwed, and will have to come up with a special plan.

My questions is regarding the "sleeve" contact on the jack, or the ground. Should I lead every sleeve contact to a common point, so that all of my gear shares a common ground, .... If I do pick one common ground point, can I just jumper all of the ground terminals to eachother? How should I wire mic lines? Should all of my patchbays share one common ground?

You don't want every device in your studio to linked together that way. You could have a bad piece of equipment grounding itself through other gear (big hum and possible crosstalk).

Thanks Greg
I have another question that maybe you could help me with. The patchbays that I am wiring are different than most I have seen. They are 1/4" military and have 4 rows of 26 patchpoints. They are by far the toughest and coolest looking patchbays I have ever seen, with huge handles and a fold-down front plate, little slots above each patchpoint for labeling, and big "tree" shaped soldering posts in the back for each contact. Aside from the sleek 5 space chassis and useful features, it has seven oldering "pins", or contacts per jack. 5 of them are easy to explain: Tip, Ring, Sleeve, Tip Insert for normalling and Ring Insert for normalling (or to break the normal, rather). Then there are these other two pins. They do not make contact with any of the other pins on the jack, and when you plug in your patch cable, the make contact with eachother (as opposed to the normalling pins which break the contact when a cable is plugged in). I guess you could jumper them to any of the other contacts on the jack, but I don't know why you would want to do that. Do you have any idea what these are/could be used for?

I hope the description was not confusing. Thanks
mike

probably something clever
does that help?


My guess is it might have been used for a non audio related switch, like an indicator or something.

someone out there probably knows what it does

I have always been told that if a clean ground is available you shouldn't lift the shield at all. This would also be assuming that a proper grounding system was used (star or common). In the event of an unruly piece of gear, you should lift the shield at the output (mainly due to the mic input problem Greg mentioned) and should remain consistent throughout.

Maybe I've had bad information given to me. Or it's more likely, I'm just confused. Either way, could you explain why lifting the shield on all pieces of gear would be a good thing in light of the above and why necessarily at the inputs? Thanks.
Spitface.

Maybe I've had bad information given to me. Or it's more likely, I'm just confused. Either way, could you explain why lifting the shield on all pieces of gear would be a good thing

Not every unit has the same internal grounding. Pin 1 on your mic preamp output could have a lower impedance (to Earth) than the next unit's input. You would have current flowing if the shield were connected. This would be the case even if both boxes' electrical ground (at AC connector) were the same.

and why necessarily at the inputs?

Outputs will work as well. Just keep in mind what will go to what bal and unbal. Your right, you have to be consistant.