Isolation jacks

[shooter]

I want to add a pseudo line out that is isolated, any problem using  a stereo jack with tip = signal, ring = signal grd and just leave sleeve unused?

thx   

[terminalgs]

I want to add a pseudo line out that is isolated, any problem using  a stereo jack with tip = signal, ring = signal grd and just leave sleeve unused?

Seems okay, so long as nothing bad would happen should someone someday plug in a regular mono plug...  Plus it means you always need that special cable...


Why not use an isolated mono jack? 

[jojokeo]

I want to add a pseudo line out that is isolated, any problem using  a stereo jack with tip = signal, ring = signal grd and just leave sleeve unused?

thx

Not following you, you want it to be like a ground lift? You will need to address the ground situation.

[shooter]

Ya, after I posted I thought about "that cable", musicians seem to have a hard time keeping paperwork from previous works done.  thanks anyway.

[terminalgs]

Ya, after I posted I thought about "that cable", musicians seem to have a hard time keeping paperwork from previous works done.  thanks anyway.

regardless,  an isolated jack,, beit a switchcraft style with isolation washers or a cliff-style isolated jack lets you isolate the sleeve from the chassis.

[PRR]

> ring = signal grd

So what are you "isolated" *from* ?

The signal ground is already on the cable, un-isolated.

I think all you done is ensure that mono plugs WILL hum. A tip/ring plug can extract signal but it still has to deal with any inter-chassis (or amp to mixer) ground differences.

[shooter]

The whole reason/thought was to eliminate a potential ground loop with pieces I have on hand.  I'm taking a pre-out into a yet to be built pa chassis that has it's own PS. 

[HotBluePlates]

The signal ground is already on the cable, un-isolated.

The whole reason/thought was to eliminate a potential ground loop with pieces I have on hand.  I'm taking a pre-out into a yet to be built pa chassis that has it's own PS. 

What PRR was saying is that your preamp probably already has signal-ground connections to the chassis, inside the preamp. Using an isolated jack doesn't change that, and both pieces of gear still get their chasses connected together by the 3rd wire of your power cords (which of itself is a GOOD THING for safety).

A real ground-lift arrangement on yet-to-be-built equipment would wire all grounds together with no connection to the chassis (though 3rd power cord wire gets attached so the breaker trips if high voltage contacts the chassis). Then insert one of several circuits to connect between the wired ground & chassis, with a SPST switch to short that arrangement and directly connect ground to chassis when you don't need the lift.

It may take a lot of thinking to make sure no component or wiring method is a sneak-path to the chassis, apart from that ground lift switch.

I've used exactly what I'm describing in amps before. When you use the equipment by itself, you'll need to be able to connect the circuit ground to the chassis to avoid buzz.

Alternatively, for already-built gear you could use an isolation transformer and an insulated jack.

[tubeswell]

The whole reason/thought was to eliminate a potential ground loop with pieces I have on hand...

The whole point about this amp building thing is that you always need to buy more stuff that you don't have on hand. :-)

[shooter]

ding ding ding circle gets the square:) !   I'm making a pedal shopping list soon so add 1 isolation jack, maybe 2!