Transformer isolated guitar splitter. Ground loop.

[Buffalo Tom]

I'm trying to build a passive guitar splitter with JENSEN JT-11P-1 as shown below. Im wiring red to input tip, brown and white to input sleeve. The input jack sleeve is connected to box/ground. Then I have yellow to output tip, orange and black to output sleeve. The output jack is isolated from the box. The transformer case is attached to box/ground. So I believe I've done everything correct but I'm getting a ground loop when using two amps. Why???. I have no other equipment then two amps, guitar and the splitter box.

[antonis]

Shouldn't Brown, White & Green be a single wire fron IN Sleeve to Box..??

[njkmonty]

this is how i wire mine..

whats the black wire for on yours?

[Buffalo Tom]

this is how i wire mine..

whats the black wire for on yours?

I think this is the correct function for each wire.

RED    PRIMARY +
BRN   PRIMARY -

YEL   SECONDARY +
ORG   SECONDARY -

WHI   CASE
BLACK ELECTROSTATIC SHIELD

[Buffalo Tom]

Can someone see what I'm doing wrong? How do I add a ground lift switch? Just connect ISO output sleeve to box ground? But adding a ground lift switch, I guess defeats the purpose of the ground isolation on the transformer... Any help much appreciated.

[njkmonty]

is this what you want to do?

[Fender3D]

Get your DMM and check if grounds are actually unconnected...

I'd connect white and black to GND and left the iso-output with just 2 wires (Y and O) to trafo.

@njk
the diagram you posted actually won't isolate out-b and out-a, since their GNDs are connected... BTW I think that GND lift switch is useless

[njkmonty]

i can see that,  i posted that mainly for the ground lift part !

[anotherjim]

Amplifiers can hum anyway. Are you sure the input connections are the cause? If the AC power supply line has a bad ground, the additional leakage current with an extra amp' on the supply could be lifting the supply ground and making it less effective.

As Fender3D said, do make sure the transformer output ground is really isolated from the others by measuring.