bbystrek wrote:
>
> Walter,
>
> Am I still sort of right - that the goal would be to ideally get the
> peak within a given recording to just reach 0dB for no more than the
> one or two samples in a row? If I understand, your clearly telling
> me that that much dynamic range is completely unnecessary (and
> perhaps even not readily later reproduced). Even worse, I see from
> some previous posts that the input on the Sony DATs has historically
> been well known to "block up" when hit too hard - something the mic
> limiter circuitry will obviously do if enabled.
In digital think of clipping as a razor. It's going to shave the
waveform off flat at OdB, at best. At times it's even worse, and it will
bounce clear to the other end of the waveform. So, if you could
perfectly get just to the OdB level, it would be ok, but remember that's
one cycle of the waveform. Your level meters or indicators are always
averaging so will not indicate these peak points. But, the digital
clipping can really mess things up with even a single clipped wave.
There is no leeway, no soft landing. That's why the pad. We frequently
get no retakes.
And in natural recording, small amounts of clipping may be hard to
detect specifically listening, but will detract from the sound. We do
sometimes deliberately allow some clipping, like in the case where we
want some quiet call and there's this foreground loudmouth. But that
should always be a deliberate choice with full understanding.
You have somewhere around 20-30 dB or more extra dynamic range compared
to good analog when recording with DAT. It's even better than that with
a good minidisc, as it uses bit shifting to gain some more range. My
portadisc is rated over 120dB of dynamic range. So you don't need to
take the risk.
Digital will carry the dynamic range through the record process, but
many listening systems don't have that much range, and there is the
question if our ears do either. Depends on whether you want to damage
your hearing. If your hearing is real good, you might hear down to 0 or
-10 dB at voice frequencies, but damage at the other end is going to
limit how far you want to go. I also believe that ears just subjected to
loud sounds probably don't hear real quiet ones. Remember, that's young
and excellent ears, probably less than 1 in 10 of 17-26 year olds back
in the early 70's when I was doing hearing tests for the military.
Average person on their best frequency was probably at 5dB.
As you noted, pushing equipment with high signals is not a good idea.
You will get cleaner sound keeping some headroom.
Anyway, if you want to look for digital clipping just take any software
that will display the waveform in detail enough to reach sample by
sample visable. Look at the top and bottom of the waveform and you will
see where it's clipped off, or as sometimes happens is clipped and the
middle of that reversed to the opposite extreme. Most of the routine
sound editors we use can do this, and if you suspect a spot is clipped
it's easy to check. No special analysis software is needed as you can do
it visually. Sometimes it's clipped unequally top and bottom, a
indication you have some DC offset in your system. Some editing software
has a ability to remove this offset, and if it's there that will improve
the sound slightly. I saw this more when I was still doing analog transfers.
Walt
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