wrote:
>
> Dear Walt,
>
> Thank you so much for your message 5/31/02 2:27:37 PM.
>
> 1. Your "picture window-kitchen window" analogy was extremely helpful.
I was not sure if it would help at all. But I figure it's worth a try.
Just to complicate it a bit, I only set the desired window as between
the loudest part of the wanted call and the mic's noise level. But, for
most environments if we are using quality mics the environment's
background is noisier than the mic. For instance in the disk full of
river frog recordings I'm processing from the trip, the insects form the
steady background, and they are between -60 dB & -40 dB on the
Portadisc's meter. The river frog calls I want barely get better than
that. But come through quite strongly as the Telinga helps focus on
them. I've got to send a clip to a couple folks, so will put up a link
when I get it done as I'll probably have the clip up for a week or two.
Just in case you are interested. The dynamic range of that environment,
calls and all was very narrow, maybe only 30-40 dB.
Even when there's not insects in such numbers, there is wind. A light
breeze is enough to raise the background quite a bit. And that is often
mistaken for mic or pre noise as it tends to be a white noise sort of
hiss. If you swing a direction mic around and get different levels of
hiss from different directions, this is a likely cause.
It can be discouraging to cart a noise meter along as I often do.
> 2. "The portadisc can be set to give you a running max level readout in
> numeric form".
>
> I tried this and it does seem helpful. This measures the "head room"
> available, not the dB level..right?
It's giving you the equivalent of the max meter reading in numeric form,
and slowed down enough to read. The number is indeed the distance in
intensity to reach 0dB, where hard clipping will occur in digital. So it
is your head room. The smaller those numbers the greater risk you are
taking. How much risk to take depends also on what sort of things are
out there. If it's some nice steady sound with no real peaks, you can go
real small on headroom, but if you can have something abruptly make loud
noises, you need much more.
It's more useful as you are getting used to the machine. After a while
you will easily pick it out of the regular meter display to within a dB
or so. The problem is that very sharp transient calls don't show well on
the regular meter. The peak hold helps, but is still a bit approximate.
> 3. I wrote "I HAVE BEEN TRANSFERRING DATA FROM MY HHB TO MY HARD DRIVE VIA MY
> PANASONIC
> > 3200 DIGITAL AUDIO TAPE DECK. I HAVE USED ANALOG OUT OF THE HHB TO ANALOG IN
> > TO THE DAT. THE DAT IS CONNECTED DIRECTLY TO MY SOUNDBLASTER LIVE SOUND CARD
> > VIA COAXIAL CABLE."
>
> You replied "Some of the noise you are experiencing is probably caused by the
> route
> you are using."
>
> However, I used this same transfer process with the TCM so the relative
> "noise level" between these two recorders should be portrayed correctly on
> the spectrogram?
As I noted, the Portadisc has a coax digital out. Try it and see if
things improve if you go direct.
For the process to give the true image between the TCM and the
Portadisc, both would have to have exactly the same output voltages and
the match into your tape deck from both would have to be equal. So maybe
it's a good comparison and maybe not. Each link you introduce can add error.
>From the results you described from your split level mono recordings, it
sounds to me like the noise you are experiencing is coming in the input
of the Portadisc. I have no idea if it's environment, or something to do
with your mic setup.
Walt
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