Wiring Problem (3PDT, LED, Input Grounded)

[Khas Evets]

I've just wired a booster using the GGG method here:

http://tinypic.com/2lxhly

The only difference in mine is that the 3PDT switches the positive side of the LED and the battery is connected through the DC jack, drawn in blue here:

http://tinypic.com/2lxjxt

I also star grounded to the input sleeve rather than the board.

So when...
1) DC jack is plugged in
2) The output jack is connected to the amp
3) The input jack is not plugged in

The LED still lights up when switched on. If I remove the cord from the amp it goes off. I'm assuming that the DC jack and amp are completing the ground side of the circuit, but it seems strange. I'm concerned about ground loops.

Is this normal?

[niftydog]

the output jack and amp are providing a current path for the LED. This in itself is not necessarily the cause of ground loops. Either design could potentially cause a ground loop.

My ground loop rule of thumb;

if a single device has two or more ground paths it has ground loop potential.

Usually the two grounds are via the power supply and either (or both) the input and/or output jacks.

Anywho...

to stop this, wire the earthy side of the LED to the input jacks ring connection and not the boards ground point. This will ensure that the LED will only work when the ring and sleeve connections are shorted together (ie; plug inserted in socket.)

[MartyMart]

Nifty, is this normal practice ?  here's why....
All my builds that have batt/9v socket will "power up" with batt and jack inserted, or with 9v adapter and NO jack inserted, ie: LED will light up in
this case when the 3DPDT switch is pushed -- its never bothered me.... and I always seem to have "quiet" noiseless builds.
I also have a few commercial pedals that will do this from 9v PSU power.
So this is a possible future "ground" problem... ??

Thanks,
Marty.

[niftydog]

Yes I often see what you describe, but it seemed that the OP may not have wanted that "feature" so I described a way of altering it.

any audio device with more than one ground point has potential for playing a part in a ground loop hum situation. Hence why I continually recommend The Spyder power supply.