rec.arts.movies.production.sound

Hi Jim,
You are doing the right things as far as tracking down your noise
sources and setting things up so the weakest link is at the beginning
of the sound chain. Basically, if the Countryman mic is adding 12 to
17 dB of noise to your setup, nothing else in the chain is going to
make any difference. The microphone is as much as 50 times noisier (17
dB) than the rest of your sound chain. Any improvement in the
receiver- mixer signal to noise, for instance, is going to give you
unmeasurable improvements.

On the other hand, you have the ideal signal chain as mentioned above;
the weakest link is at the beginning. Nothing that you do downstream
is going to make the signal to noise ratio worse (within reason).
Given a particular mic all you can do is increase the signal at the
mic, ., get it closer to the performer and reduce the noise, .,
quiet the room.

The reason the noise drops when you unplug the mic is obvious. The
radical drop in noise when you turn off the transmitter is somewhat an
illusion. When the transmitter is off, the receiver output is
disconnected and the relay shorts the XLR outputs to ground. It's hard
to beat a short for quiet. Substituting mics just shows that the
Countryman is typical for noise and/or the room noise may be the major
culprit here.
Best Regards,
Larry Fisher
Lectrosonics

On Tue, 25 Sep 2007 13:03:26 -0700, clmjhb@ wrote:

[snip]

>I made a recording and then measured the dB results in Pro Tools.
>With the mic just recording the sound of a very quiet room, I got -43
>dB in Pro Tools. With the B3 unplugged from the transmitter, I got
>-55 dB (conclusion: the B3 is adding some noise, that low-level
>ssshhhh-type hiss in the background). With the transmitter turned
>off, I got -84 dB (conclusion: the transmitter is adding some noise,
>but the receiver seems to be absolutely quiet when it is not getting a
>signal).
[snip]

>I also tried these settings with a Sanken CUB boundary mic, and it was
>a little quieter than the B3.
>
[snip]

>Jim