Recording old cassette's into PC. 88/96k + 24bit - is it o..

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On Fri, 08 Apr 2005 21:38:19 +0100, WhoRu <who@ru> wrote:

>OK well then it seems the best option is to record all the cassettes
>in at 44k 16 bit with no processing of any kind (no dither)

There's an error here.

>I had considered whether to record in at 24bit, dithering down to save
>at 16bit via ultramax purely to use the full potential of my A/D's so
>possibly getting a better end result than purely using the A/D's at 16
>bit. But to be honest all you ever read is that dither MIST be the
>last thing you do. This seems to mean that 24bit--dither-->16bit will
>be worse than direct 16 bit with no dither?

*All* word length reductions must be dithered (to avoid yada yada).
This includes any analog to digital conversion. This whole thread
has been based on the assumption (good one too) that any real tape
will make enough noise so as to be much bigger than even a 16 bit
converter's LSB quantization errors.

IOW, the tape's noise will (possibly/ probably) dither the conversion
pretty well no matter what. But still:

You should still dither any word length reduction, including A/D
conversion. It's The Cowboy Way. And years later, you won't be
staying up late at night wishing, and wondering...

Good fortune,

Chris Hornbeck
6x9=42

 

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On Fri, 08 Apr 2005 21:38:19 +0100, WhoRu <who@ru> wrote:
---------------8<-----------------------------
>
>Anyway I'll tweak the azimuth before each tape and will begin grabbing
>them, (unless anyone has any last comments to make?)

Yes, I forgot to mention that it could be necessary to demagnetize
your cassette tape deck heads by a hand demagnetizer. The procedures
are discussed at various places at the Internet. This in some
circumstances could have a "wow" effect. This, plus cleaned heads and
tape path, properly adjusted azimuth for every cassette and its side
as well as matching noise reduction setting (whatever the tape has
been recorded with, if any) will ensure you optimal reproduction from
the analog part. And then you could choose bit depth, sampling rate
and so on (some editor programs have an option to work and save
temporarily files 32 bit, it can add to "internal" precision during
work no matter what bit depth you're working with. It also adds to
working payload though).

Edi Zubovic, Crikvenica, Croatia

 

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On Sat, 09 Apr 2005 06:34:52 GMT, "Paul Stamler"
<pstamlerhell@pobox.com> wrote:

>>Personally, since you're planning to run these through Wavelab, I'd suggest
>storing the files in 32-bit float, so it can have the format it likes. I

I don't see the point of storing files at 32 bit, that doubles the
file size for no gain whatsoever, from what I've ascertained.
Obviously when I later come to remaster it wavelab will start with a
16bit file and internally as it runs through plugins do so at 32 bit
float regardless and dither back down to 16 bits at the end after
processing. Whather the source is 16 or 32 bit will make no difference
to wavelab, 32 bit would just mean extra dynamic range resolution that
won't exist on a cassette - correct?

Part of my confusion about dither was everything you read says to
dither down only as the last stage, BUT in this case I am preparing
raw copies of audio cassettes that it seems will not benefit from
going above 16bit/44k, then dither is OK I presume, though possibly
unneccessary as the inherant noise of a cassette will mean the high
bits are in a state of flux anyway. The main thrust of the thread was
to determine if anything greater than 16/44k was overkill which it
seems it is. I certainly dont wish to create larger files
unnecessarily, especially as when I tested flac on a 24 bit file it
made no difference but on a 16bit reduced it by about 30%, that's if I
decide to use it.

Bottom line is as it seems 16/44k is more than adequate to capture the
freq response of a cassette, there is no point using any higher.
Regarding dither there is no problem recording at 24 bit if I wish
with a dither down to 16 bit on the output and saving at 16 bit (on
the fly as I can do in wavelab).

 

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On Sat, 09 Apr 2005 09:31:15 +0200, Edi Zubovic <edi.zubovic[rem
this].@ri.htnet.hr> wrote:

>the analog part. And then you could choose bit depth, sampling rate
>and so on (some editor programs have an option to work and save
>temporarily files 32 bit, it can add to "internal" precision during
>work no matter what bit depth you're working with. It also adds to
>working payload though).
>
the chip in my pc is easily powerfull enough to run the 4 or 5 plugins
I need at 32bit res in real time when remastering, so there will be no
temporary files and no payload. I just dont want to being with higher
res files than I need as there may be 100+ tapes to do and don't want
to bunr more dvd's than necessary. Some people seem to say "no harm
storing at 24 bit" but if there is no gain then there is no point.
Arny says the res of a tape is 8-10 bits so... Also as I am recording
in via my dbx386 (dbx4 = no fear of clipping) and boosting the input
to -8 to -2 db range its pretty hot so is already using all the bits.
Wavelab bit meter shows the first 2 bits permanantly on anyway even
when there's no signal.

 

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"WhoRu" <who@ru> wrote ...
> the chip in my pc is easily powerfull enough to run the
> 4 or 5 plugins I need at 32bit res in real time when
> remastering, so there will be no temporary files and
> no payload. I just dont want to being with higher res
> files than I need as there may be 100+ tapes to do and
> don't want to bunr more dvd's than necessary. Some
> people seem to say "no arm storing at 24 bit" but if
> there is no gain then there is no point. Arny says the
> res of a tape is 8-10 bits so... Also as I am recording
> in via my dbx386 (dbx4 = no fear of clipping) and
> boosting the input to -8 to -2 db range its pretty hot so
> is already using all the bits. Wavelab bit meter shows
> the first 2 bits permanantly on anyway even when
> there's no signal.

I'd have to agree with Arny. You would be really lucky to
get 16 bits worth of dynamic range our of your old cassettes.
Storing 32 (or even 24) is just silly and wasteful, particularly
if you have "100+ tapes". 88K or 96K sampling rate also
seems optimistic at best. Stick with 44K x 16bit and get
on with your life.