Re: SR monitoring noise

Hi Tom,
You are dealing with a ground loop problem and low level signals, a
combination tailor made for despair and poor signal to noise ratio.
The SR is grounded in the slot to the camera as well as the camera
chassis. It is also grounded to the external pin 1 input of the
camera. The big loop is the external 5 pin to XLR cable and the
chassis of the SR. The noise generator is the camera power and/or the
SR power supplies. The reason I think this is true, is that the signal
on the 5 pin connector is identical to the signal on the multi pin
connector in the slot. Inside the SR there is a coax audio cable
running from the multi pin connector driver up to the 5 pin wart.In
fact, if you short the 5 pin signal you will lose the signal to the
multi pin adapter in the slot. In a perfect setup, there should be
zero difference in the SNR of the slot or the 5 pin wart. Mic level
signals are bad since they are always prone to interference or ground
loops. We use them because we have to, not because we want to.

You can try an experiment, if you haven't, and that is to remove the
pin 1 connection in the XLR to the camera external input. All shields
and parts will remain at ground but you will have interrupted the
external loop. This will leave only internal loops inside the camera
and may solve the noise problem if the manufacturer has been careful
about taking all the grounds back to a common point. Let us know and
we'll add the pin 1 delete to the manual and to an FAQ.


On Mon, 2 Mar 2009 09:36:30 -0800 (PST), campatom@xxxxxxxx wrote:

Thanks Scott for trying to help really .But that was not the question
I asked , I understand about the line level in and max level output of
the SR and I do appreciate your reply trying to get me the best
sounding option .I'm working on a level test and calibration between
'wireless' switch and mic level in , trying to keep the same level
output on the SR and the same gain position on the camera to be able
to go back and forth between 'wireless' for one channel and then two
channels with the mic level in . Question is : Is their more hiss when
using mic level out of the 5P ( channel two or one for that matter )
than the UniSlot channel 1 .
Thanks.
Tom
.

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