Resilience of digital on video tape

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I'm transferring all my PCM-F1 recordings (1984-1996) to computer via a PCM
601 processor with S/PDIF output.

I'm amazed at how well these 20 year old tapes are tranferring. No
significant dropouts in the first 18 tapes. Only a hundred more to go...
I haven't gotten to the couple of tapes recorded at slow speed. I don't
have much hope for those.

I blew a whole $50 on a new VCR so I could read the VHS tapes with new
heads.

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In article <Xns96AB7934CC96Ablindhog@140.99.99.130> blind_hog@acorn.com writes:

> I'm transferring all my PCM-F1 recordings (1984-1996) to computer via a PCM
> 601 processor with S/PDIF output.
>
> I'm amazed at how well these 20 year old tapes are tranferring. No
> significant dropouts in the first 18 tapes. Only a hundred more to go...

In the past few months, I've dug out four and tried to play them. Two
played fine. Two were so full of dropouts that they were quite
unusable, at least on my VCR. These are all Beta format.




--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
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and reach me here: double-m-eleven-double-zero at yahoo

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mrivers@d-and-d.com (Mike Rivers) wrote in news:znr1123445097k@trad:

>
> In article <Xns96AB7934CC96Ablindhog@140.99.99.130>
> blind_hog@acorn.com writes:
>
>> I'm transferring all my PCM-F1 recordings (1984-1996) to computer via
>> a PCM 601 processor with S/PDIF output.
>>
>> I'm amazed at how well these 20 year old tapes are tranferring. No
>> significant dropouts in the first 18 tapes. Only a hundred more to
>> go...
>
> In the past few months, I've dug out four and tried to play them. Two
> played fine. Two were so full of dropouts that they were quite
> unusable, at least on my VCR. These are all Beta format.

I guess find a VCR with newer heads is kinda out of the question...

Archived from groups: rec.audio.pro (More info?)

Blind, just from curiosity, how are you dealing with the pre-emphasis
issue? The PCM-F1 always recorded with pre-emphasis (treble boost), so
the S/P-DIF bitstream coming out of the PCM 601 will have this
characteristic as well.

But .WAV files don't have a standard way to indicate that this emphasis
has been applied. As a result, when you burn CDs from the wave audio
files, you always need to set the pre-emphasis flag on the CD tracks in
the CD burning software, so that the pre-emphasis flag will be recorded
on the CD. Only in that way can the CD player apply the compensating
treble reduction. If you don't do something about this, all your CDs
that come from F1 sources will play back with 10 dB of boost above 4
kHz or so.

I use Golden Hawk's software for burning most audio CDs; its cue sheets
include a way to signal that a track's source material has
pre-emphasis. But pre-emphasis isn't used much any more, and I haven't
seen this feature in other recent CD burning programs. That's why I'm
asking--I'd like to know what other software supports this type of
transfer.

--best regards

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David Satz <DSatz@msn.com> wrote:
>
>I use Golden Hawk's software for burning most audio CDs; its cue sheets
>include a way to signal that a track's source material has
>pre-emphasis. But pre-emphasis isn't used much any more, and I haven't
>seen this feature in other recent CD burning programs. That's why I'm
>asking--I'd like to know what other software supports this type of
>transfer.

Another way of dealing with this, and probably the more common one today,
is to apply a de-emphasis filter in software once you've loaded the file.

I've been doing this a lot, since I have a lot of tapes I recorded with
a Tascam DA P-20, which had nondefeatable emphasis.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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"David Satz" <DSatz@msn.com> wrote in news:1123518322.687186.48960
@g43g2000cwa.googlegroups.com:

> Blind,

My apologies to all readers. I've changed ISP's and newsreaders, put up a
bogus name during the conversion, and forgot to remove it before beginning
normal conversation again.

Message from the old blind hog are from me.
--Carey Carlan

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kludge@panix.com (Scott Dorsey) wrote in
newsdac0l$imp$1@panix2.panix.com:

>>"10 dB above 4kHz or so" sounds pretty vague.
>
> EIAJ has 15 and 50 microsecond time constants as I recall. This would
> give you:
>
> =======================================================
> kHz 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
> -dB 0.0 0.0 0.0 0.1 0.1 0.1 0.2 0.2 0.3
> =======================================================
> kHz 1 2 3 4 5 6 7 8 9 10
> -dB 0.4 1.3 2.4 3.5 4.5 5.4 6.1 6.7 7.2 7.6
> =======================================================
> kHz 11 12 13 14 15 16 17 18 19 20
> -dB 8.0 8.2 8.5 8.7 8.9 9.0 9.2 9.3 9.4 9.5
> =======================================================
> (chart shamelessly stolen from Tom McCready, but there is
> a copy of this in the Tascam DA-30 review in the July 1991
> issue of Studio Sound)
> --scott

I'm listening to the digitally-transferred recordings and don't hear
anything like that kind of rise in the signal. +3.5 dB at 4K should be
pretty obvious, and, with only a -54 dB noise floor in the mic preamps, I
should be getting intense amounts of hiss. Don't hear that either.

Could the 601 be doing de-emphasis out the digital port? How could I find
out? Guess I could record a sweep or pink noise.

Archived from groups: rec.audio.pro (More info?)

(Scott Dorsey) wrote:

>>> I've been doing this a lot, since I have a lot of tapes I recorded with
>>> a Tascam DA P-20, which had nondefeatable emphasis.
>>
>>What does that curve look like?
>>
>>"10 dB above 4kHz or so" sounds pretty vague.
>
>EIAJ has 15 and 50 microsecond time constants as I recall. This would give
>you:
>
>=======================================================
>kHz 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
>-dB 0.0 0.0 0.0 0.1 0.1 0.1 0.2 0.2 0.3
>=======================================================
>kHz 1 2 3 4 5 6 7 8 9 10
>-dB 0.4 1.3 2.4 3.5 4.5 5.4 6.1 6.7 7.2 7.6
>=======================================================
>kHz 11 12 13 14 15 16 17 18 19 20
>-dB 8.0 8.2 8.5 8.7 8.9 9.0 9.2 9.3 9.4 9.5
>=======================================================
>(chart shamelessly stolen from Tom McCready, but there is
>a copy of this in the Tascam DA-30 review in the July 1991
>issue of Studio Sound)

One can calculate the theoretical pre-emphasis curve frequency
response from the following relationship:

y = 10log(A/B)

where y = dB output at a frequency of f Hz
A = 1 + (L x L)
B = 1 + (H x H)
H = (2 x pi x f x t(H))
L = (2 x pi x f x t(L))
t(H) = high freq. time-const, in sec (= 0.000015)
t(L) = low freq. time-const, in sec (= 0.000050)

For de-emphasis, reverse the sign of y.

A clunky, but exact, formula - just layer it into a spreadsheet to
cobble up a quick 'n dirty graph.

Certain software de-emphasis plugin presets, e.g. Waves, sound OK but
don't measure all that closely to the theoretical curve. I'm unaware
of any soundcard which de-emphasies an incoming s/pdif stream and
stores to 'straight' straight wav -all done in the digital domain. But
rme cards can detect pre-emphasis flags and apply de-emphasis in a DA
stage - so that you can at least monitor 'straight' while writing the
still-emphasised wav to hard disk .

Tom McCreadie

Live at The London Palindrome - ABBA