Input/output jacks: ground to case?

[Bucksears]

I've found that the input/output jacks are connecting with the inside of the case thereby connecting the case and jack ground tabs. Is it better to separate the jacks from the case or to include the case as the ground? Basically, I wire up one of the jacks' ground tab to the board, then connect the grounding to other off-board components to those tabs as well.
Is this a bad idea in terms of noise or are others doing it this way too?

Thanks,
Buck

[GibsonGM]

Hi Buck,

There are a couple of schools of thought on that one.  Look up "star grounding".  In that scheme, you isolate the jacks with nylon washers (etc), and all grounds go to 1 point on the chassis/enclosure.  There's high opinion of this, since it avoids ground loops, and many believe star gnd to be the quietest setup.  Drawback - you lose the ability to switch at the input jack, bc the battery/PS ground goes to the case rather than the sleeve of the input jack, so you have to have an on/off power switch.  Personally, I think the benefits are minimal - the tube amp I just built uses 3 grounds, and is just as quiet as if done with star gnd (I tried both).

OTOH, it's generally OK to ground everything in a stompbox to the input jack ("switching trick").  I have always used this method - I don't connect a ground to the output jack, avoiding that loop, so of course I don't isolate any of the jacks.  The enclosure itself grounds the output jack - it is also an RF shield for the whole circuit.   Looking at the Tonepad "Offboard Wiring" PDF that's floating around shows this method, which I believe to be "the best way".
 
High gain circuits are usually (always?) going to have thermal noise and hiss...really, really good grounding is typically reserved for 'quiet' boxes, like chorus, EQ, etc, and even then there is a 'noise floor' due to your amp, cable runs, pickups, etc.

[cpnyc23]

In case anyone is looking for it, the above mentioned Tone Pad "Off Board Wiring" pdf can be found at

http://tonepad.com/getFileInfo.asp?id=76

-chris

[mac]

I use the output jack as the gnd point because I solder the pull down resistor across the input jack. Jacks are not isolated.  I've compared with the input jack method and I had the same result. But my builds are just a few.

mac