Mic splitter ground lift kills phantom 48V... Why?

[XLR2XLR]

I was pre testing some rig and 2 single channels splitters were included.

EWI and Horizon.

The Horizon killed phantom when the ground was lifted but the EWI does not?
(The EWI has 2 ground switches, one for input and output I suspect)

Strange that one does switch phantom off and one does not, they sound very similar
to each other but this is an inportant trait to understand.

Anyone care to shed light on why one kills phantom and the other does not?

[roonsbane]

I suspect the lifts are on each output. One being the direct, the other being the transformer isolated. This is pretty standard. If you lift ground on the direct output, there goes your phantom.
Cameron

[Rick Sutton]

Phantom sends 48 volts DC down the positive and negative signal legs and the circuit is completed with the ground/shield of the mic cable. If the shield is lifted on the way back to the phantom generating source the circuit is broken and the phantom will not work. A splitter usually allows for one direct path (which has to be the path supplying the phantom) and one or more transformer isolated paths. The transformer paths cannot pass phantom as transformers block DC. The ground lift is usually used on the transformer coupled splits if there are ground potential problems (hum) with the two mixers tied together. You probably know all this!

[Remoteness]

Lifting pin one on the input or output XLR will prevent Phantom power to operate.
Refer to the above posts for the details.

IMO you should never wire a ground lift switch to the input side which is daisy chained to the direct output connector(s) -- PERIOD!

Ground lift switches should only be used for the isolated outputs.
Most splitters have a ground lift switch that can lift "pin one" of each channel XLR on all isolated outputs.

You can also design/build/buy a splitter that has two ground lift switches per channel to lift each isolated outputs separately.

Some (usually) active splitters like the BSS variety have no ground (pin one) connected on the isolated outputs.

We have all versions depending on the splitter system we're using at the time.

[XLR2XLR]

Sorry to be a slow getting back on this one.

I have read the above statements.

The EWI has 2 ground lift switches.

On the Horizon the direct output had phantom supplied (as you would expect)
So the lift seemed to lift ground on the direct output (otherwise the LDC connected would still work)

I am not sure that 48V is sent down the +/-, I thought it was the + and ground/screen
as when I recently checked phantom volts on a preamp the DC meter read nothing on the +/- pins, only against + / ground did the anticipated volts get shown (remember some US gear is wired differently than here in the UK using XLR's, so best avoid pin numbers and stick to + / - and / ground)

Anyway I have many channels of EWI split but only 1 Horizon (I am glad, I think !)
I shipped them over from the USA and paid import tax and they still blew anything away that is possible to buy here. They are very good for the money.

[Rick Sutton]

Originally Posted by XLR2XLR

Sorry to be a slow getting back on this one.

I have read the above statements.

The EWI has 2 ground lift switches.

On the Horizon the direct output had phantom supplied (as you would expect)
So the lift seemed to lift ground on the direct output (otherwise the LDC connected would still work)

I am not sure that 48V is sent down the +/-, I thought it was the + and ground/screen
as when I recently checked phantom volts on a preamp the DC meter read nothing on the +/- pins, only against + / ground did the anticipated volts get shown (remember some US gear is wired differently than here in the UK using XLR's, so best avoid pin numbers and stick to + / - and / ground)

Anyway I have many channels of EWI split but only 1 Horizon (I am glad, I think !)
I shipped them over from the USA and paid import tax and they still blew anything away that is possible to buy here. They are very good for the money.

Phantom runs positive voltage down both the + and - mic lines and the shield is used as return. It is important that it be on both signal lines, and you should be able to measure it as full voltage from + to ground and from - to ground. If not, something is wrong.

[XLR2XLR]

Ok will check that, thanks for sharing.

[Remoteness]

The bumpnesses of all bumps...

So, did you find out if you were able to measure full voltage from plus to ground and from negative to ground?

Originally Posted by XLR2XLR

Ok will check that, thanks for sharing.

[mixedupsteve]

I'd just like to clear up one thing that may cause misunderstanding. If mixer A supplies phantom and the ground is lifted at the output from the splitter to it and mixer Bs ground is not lifted then the phantom powered device will still work because it has a ground source. It doesn't matter if the path to ground is supplied by the same mixer or preamp as the +voltage.