wrote:
> 1. "10 dB is, if I remember correct exactly how much the signal is reduce=
d
> by the portadisc if you use mono and only send the signal in one input."
>
> I USED A Y CABLE AND HAD BOTH LINE INPUTS IN USE SO I SHOULD NOT HAVE
> SUFFERED SIGNAL LOSE. I DID SOME RECORDING IN STEREO ( 2 1/2 HOURS) AND T=
HE
> GAIN WAS THE SAME BECAUSE I SENT THE SIGNAL TO BOTH INPUTS.
There is some loss for a Y cable, but it's not that much.
> 2. "Note that the NIMH batteries now come in 1800 mah capacity from a cou=
ple
> manufacturers".
>
> THAT IS GOOD NEWS. DOES THE LIFE OF THE BATTERY INCREASE IN PROPORTION TO=
THE
> MAH CAPACITY..SO THAT 1800 IS 1800/1550 (16%) LONGER LIVED THAN THE 1550?
Yep, this is just like the amp hour rating of a deep charge battery.
Except it's in milliamps instead of amps. You should get somewhere
around that percentage longer, though note I've not tested it. My usage
is not as demanding as yours.
The actual capacity is variable from battery to battery. The 1800 rating
is actually low by 30-50 mah according to the info provided. That was
probably true of the 1550's as well, however. They set the value so that
some smarty won't find a battery that does not meet it.
> 3. As we've discussed, the habit of setting the meter right up at the peg=
,
> which was necessary with tape due to it's poorer dynamic range is
> something to get away from for digital recording. With the portadisc you
> have a dynamic range better than your mic, and should set the levels
> down 10-20dB lower than you would for cassette. It will still get
> everything your mic produces.
>
> DOES THIS MEAN THAT SOMETHING RECORDED AT -30DB WILL LOOK THE SAME (AND M=
ORE
> IMPORTANTLY, SOUND THE SAME) ONCE IT IS CONVERTED TO A WAVE FILE AND THE
> AMPLITUDE INCREASED APPROPRIATELY? THERE MUST BE SOME LEVEL OF dB WHERE T=
HE
> MACHINE IS UNABLE TO PRINT THE TOTAL SONG/CALL? THIS IS AN IMPORTANT QUES=
TION
> FOR ME AS I WOULD DEARLY LOVE NOT TO USE THE SME-BA3 Hi Gain Booster.
It should. You would still have a remaining dynamic range of greater
than 60 dB. The Portadisc is rated at a dynamic range of greater than 94
dB.
The critical question is what's the dynamic range of the call and of the
mic. You can fiddle around trying to figure the numbers, but I suggest
you just try it. I normally set mine up for a max dB of -20 dB, but may
go greater if not sure of the max level I might see. The portadisc can
be set to give you a running max level readout in numeric form, useful
for examining what's happening in greater detail.
> 4. "One thing that might help is to leave the phone level knob extended.
> It's next to the power button and might fend things off a little.
>
> GOOD IDEA! I'LL TRY IT.
Also look into how and when it gets turned on. You may be able to modify
how you transport it to eliminate the problem. It's definitely not a
problem I have.
>
> 6. "If you hook only to one input, then it adds that input to the signal =
from
> the unconnectedinput and still attenuates. Try comparing the gain you get
> with your mic
> feeding a single channel of stereo vs the mono fed via a single channel."
>
> AS I SAID ABOVE, THE MICROPHONE SIGNAL WENT TO BOTH MIC/LINE INPUTS SO TH=
AT I
> SEEMED TO HAVE THE SAME GAIN WHETHER THE MACHINE WAS SET TO STEREO OR MON=
O.
> DOES THIS SOUND CORRECT?
Yes this should give you the same gain. As I noted the Y splitter will
result in a few dB loss which would be in both the mono and stereo. I
avoid even that by always recording in stereo, and if it's a mono mic
just plugging it in one channel. Software in the computer can put it on
both channels.
> 7. "Digital recording has considerable more dynamic range than cassette. =
I
> suspect the noise you are seeing is either actually there in the
> environment, or is the noise floor of your mic, most likely the latter.
> In either case the cassette did not have the dynamic range to pick it up.=
"
>
> SO DOES THIS MEAN THAT DIGITAL RECORDINGS WILL USUALLY BE "NOISIER" THAN
> CASSETTES? THE NOISE I AM TALKING ABOUT IS UNIFORMLY HIGHER THROUGH THE
> ENTIRE RANGE OF dB. ON THE SPECTRAL ANALYSIS THE ENTIRE BACKGROUND IS
> "DARKER" FOR THE MD RECORDING (EVEN WHEN THE SONG FROM THE CASSETTE AND M=
D
> ARE OF EQUAL LEVELS.
This is often a impression folks new to digital talk about. When you set
them to the same level you will see whatever the greater dynamic range
of the digital captured. So it seems nosier because the digital caught
more of the signal than the cassette did. Also the cleaner reproduction
makes the quieter sounds stand out more.
Note it's also possible that the noise is from a noisy pre or whatever.
It could also be from the external pre you are using or it's interaction
with the portadisc. The portadisc is rated at greater than 89 dB signal
to noise, and the mods done to yours are supposed to have increased
that, made it even quieter.
Fundamentally digital recordings are actually quieter and clearer as far
as unwanted noise. Tape has a bunch of noises that digital does not have.
> 8. "ATRAC does, as has been noted leave out some of the dynamic range at =
the
> highest frequencies. Most of what it leaves out we probably don't want,
> mic noise and such like. It's like it cuts the dynamic range keeping the
> louder signals and dropping the quieter ones. This occurs above 16 or 17 =
khz."
>
> THIS SEEMS TO DESCRIBE EXACTLY WHAT I AM SEEING IN THE SPECTRAL ANALYSIS.
> THIS IS A SLIGHT PROBLEM FOE THE HIGH PITCHED SINGERS..I GUESS FOR THE
> SCIENTISTS?
A scientist working in this higher frequency range should be using a
much higher sampling rate, even with no compression the sound
reproduction is not good. I'm not sure singers get that high. I'm pretty
certain that few hear that high in a way to hear the lost sound. I'm 70
dB down at those frequencies, it would have to be a sound approaching 80
dB for me to hear it even faintly. And a lot louder than that to hear it
mixed with lower frequencies.
Note what I said, the louder parts of the sound at those high
frequencies are not filtered out. I once worked out that most of the
cutoff was at a sound level 50 dB or more below the louder sounds of
that range. That means, say if the call of interest is at 80 dB then the
cutoff starts at 30 dB. In my case that would mean by the time I got the
lost sound amplified enough the main high frequency sound would be at
130 dB and very painful and damaging to what's left of my hearing. And
that's for the loudest of the lost sound.
Sonograms are nice things, but not everything you see in them is
important, even if it's not a artifact of the calculations to produce
them. A lot of what people think are harmonics in sonograms are actually
calculation artifacts. This is particularly true of loud sounds.
Walt
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