Maybe a 48v issue

Hi everybody,

I'm doing live sound with one of my EZ1073.

The setup is:

KMS 105 to a splitter.
The first output of the splitter is feeding my EZ1073 wich send the 48V.  The preamp is going to FOH desk.
The second output of the splitter is isolated with a transformer and is feeding the monitor desk.

Everything sound ok except a randomly short strange sound with occur on both desk (FOH and monitor).
It sound like something charging or discharging.

When i remove my preamp  and use the FOH desk as preamp everything looks ok.
When i'm listening my preamp in a  simple configuration (a condenser mic direct in the preamp) it works fine.

I've check the 48V on my preamp which looks stable and ok.

sample of this sound:
https://soundcloud.com/user276279556/sets/strange-sound

Any ideas?

Thanks

Morgan

Hi,

Nobody?

Any ideas?

Thanks.

Morgan

Did you try this setup with an another condenser microphone?

Follow the current..

where is mic getting phantom voltage and where is the pin 1 return current flowing?

you mention a transformer isolated split. Phantom voltage will not flow through a transformer iso.

Is there and weirdness with pin 1 path?

JR

Hi, thanks for the reply,

@Moamps:

I didn't try the preamp with FOH/Monitor configuration with another condenser. But the KMS 105 was used all this summer with no issues.

@JohnRoberts:

This splitter is: 1 in and 2 outs but only 1 out is transformer isolated.
My preamp is feeding the 48v on the non isolated out.

So i need to check the pin 1 return current flowing.

(I don't know what really happening in the splitter for that. Is there a common ground? I need to check that)

Thanks

Morgan