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While I'm probably not as expert as some on this list, my standard practice
is to do a flat transfer at 96kHz/24 bits and then carry out any noise
reduction as a separate process. This allows me to concentrate on the tape
transfer without having to worry about calibrating the noise reduction at
the same time. I could also experiment with different hardware or software
at a later date. Storage is cheap - especially when using .FLAC files as
intermediate files so nearly every step is kept.

Cheers,

James.

On Mon, 15 Jul 2019 at 06:24, Shai Drori <[log in to unmask]> wrote:

> Jamie please contact me off list.
>
> Cheers
> Shai Drori
> Expert digitization services for Audio Video
> 3K scanning for film 8mm-35mm
> Timeless Recordings Music Label
> www.audiovideofilm.com
> [log in to unmask]
> Tripadvisor level 6 contributor, level 15 restaurant expert
>
>
> On Sun, Jul 14, 2019 at 10:27 PM Abhimonyu Deb <
> [log in to unmask]> wrote:
>
> > Hi Richard,
> > As to my question, am I the only proponent of recording the raw,
> > undecoded output? It's saved my bacon more than once, and I've been
> > insisting on it for at least a decade. I was hoping that some
> > standards/best practice body recommended it. I did not think I was alone.
> > IASA-TC 03 (2017) addresses this in a very, very general and vague sense.
> > It says in chapter 7 (Optimal signal retrieval from original carriers),
> in
> > the last paragraph before "Comments":
> > As in other fields of historical research, the use of cautiously chosen
> > approximations is permissible when necessary. As a matter of principle,
> > however, all such decisions must be documented, and irreversible steps
> > should be avoided. All unnecessary subjective treatments must only be
> > applied to access copies.
> >
> > Although Dolby A is hardly subjective, it may be prone to error if not
> > played back correctly and, therefore, may fall within this clause.
> > The document also states in the previous paragraph:
> > Digital carrier-based formats may contain various types of sub-code
> > information, that is, secondary information written in parallel with the
> > primary information bitstream. Incompatibilities between recording and
> > replay devices can result in this information being retrieved incorrectly
> > or not at all. Understanding the properties of a given format or
> > collection, including any sub-code information, and defining the minimum
> > required combination of primary and secondary information prior to its
> > digitisation, is of utmost importance (see section 2).
> > Although this is about digital carriers, if we extend the logic to the
> > analog domain, shouldn't it apply to the recording of the bias frequency
> as
> > well? It's a long stretch, but I was just thinking.
> > Cheers,
> > Abhimonyu DebAudio Consultant and Digitization Specialisthttps://
> > www.linkedin.com/in/abhimonyudeb
> >
> >
> >     On Monday, 15 July, 2019, 06:25:06 am IST, Richard L. Hess <
> > [log in to unmask]> wrote:
> >
> >  Hi, Corey and Gary,
> >
> > Thanks for your kind remarks about the decoder. My colleague and friend,
> > John Dyson has done a wonderful job with the code. His acid tests have
> > been leaked Dolby recordings of 70s pop music--some of them sound so bad
> > until he decodes them...but they are tougher than the stuff I've
> > recorded and obtained from other sources.
> >
> > What has happened is the intermod that is normally generated by fast
> > gain changes on decoding is vastly reduced.
> >
> > As to my question, am I the only proponent of recording the raw,
> > undecoded output? It's saved my bacon more than once, and I've been
> > insisting on it for at least a decade. I was hoping that some
> > standards/best practice body recommended it. I did not think I was alone.
> >
> > John Chester, thanks for the info on 384 kHz sampling frequency and bias.
> >
> > Remember my effort here?
> > http://richardhess.com/notes/2008/02/02/tape-recorder-bias-frequencies/
> >
> > The only major recorders that are problematic (i.e. bias frequencies
> > above 180 kHz are:
> >
> > Ampex ATR-100 (432 kHz)
> > Sony APR-5000 and probably multitracks (400 kHz)
> > Studer A80VU (240 kHz, most late models are 150 or 153.6 kHz,
> >               the A77 is 120 kHz)
> > Otari MTR-10/12 and MTR-90 (246-250 kHz)
> >
> > Cheers,
> >
> > Richard
> >
> >
> > On 2019-07-14 7:16 p.m., Gary A. Galo wrote:
> > > Hi Richard,
> > >
> > > I echo Corey Bailey's email in congratulating you on the software-based
> > NR decoder. I'm sure there will be a considerable market for it.
> > >
> > > The issue of preserving the "original" data - whether analog of digital
> > - is a sticky and controversial one. When I gave my ARSC presentation on
> > transferring PCM-F1 format digital recordings for the NY ARSC chapter
> April
> > 2018, I was taken to task by one attendee for not preserving the original
> > bits. I go from the S/PDIF output of my PCM-601ESD digital processor
> > directly into a Tascam DA-3000 digital recorder. The Tascam has a
> built-in,
> > switchable sample rate converter based on the Cirrus Logic CS8422 SRC
> chip
> > (which doubles as the S/PDIF input receiver). I set the Tascam to record
> at
> > 88.2 kHz, so the CS8422 is converting 44.056 to 88.2. An "undocumented
> > feature" of the DA-3000 recorder is that the CS8422 SRC chip also does
> > 50/15 uSec de-emphasis, which take care of another issue with F1
> > recordings. Why Tascam fails to mention this anywhere in their manual or
> > product literature is beyond me, because the de-emphasis feature is
> clearly
> > stated on the front page of the CS-8422 data sheet, and it's an extremely
> > useful feature.
> > >
> > > With this method, only the inter-channel time delay and DC offset still
> > need to be addressed once the 88.2 kHz data is on your computer.
> > >
> > > My method does not save the original 44.056 kHz bits. Guilty as
> charged.
> > But, the CS8422 does a beautiful job with the SRC and the de-emphasis,
> and
> > has ultra-low jitter clock recovery to boot, so I sleep well at night. If
> > you feel the need to preserve the original bits, you could run a second,
> > raw transfer directly into your computer, if your computer will lock onto
> > 44.056 kHz. Or, you could use a digital distribution device to split the
> > 44.056 kHz data stream, sending it to both the computer, and the DA-3000
> > recorder simultaneously. But, I just don't see the need.
> > >
> > > So there is no misunderstanding, I can well understand the desire to
> > preserve the non-decoded Dolby-A analog signal in case better software
> > conversion becomes available down the road. It makes sense to do this.
> So,
> > perhaps I'm being inconsistent. These are thorny issues, and everyone
> will
> > have their own viewpoints.
> > >
> > > Best,
> > > Gary
> > >
> > > ____________________________
> > >
> > > Gary Galo
> > > Audio Engineer Emeritus
> > > The Crane School of Music
> > > SUNY at Potsdam, NY 13676
> > >
> > > "Great art presupposes the alert mind of the educated listener."
> > > Arnold Schoenberg
> > >
> > > "A true artist doesn't want to be admired, he wants to be believed."
> > > Igor Markevitch
> > >
> > > "If you design an audio system based on the premise that nothing is
> > audible,
> > > on that system nothing will be audible."
> > > G. Galo
> > >
> > > -----Original Message-----
> > > From: Association for Recorded Sound Discussion List [mailto:
> > [log in to unmask]] On Behalf Of Richard L. Hess
> > > Sent: Sunday, July 14, 2019 5:42 PM
> > > To: [log in to unmask]
> > > Subject: [EXTERNAL] [ARSCLIST] Preserving both raw and decoded files
> for
> > tapes recorded with Noise Reduction?
> > >
> > > Hi, I think many of us agree that it's necessary to preserve both the
> > > raw transfer and the decoded version of a file which has been recorded
> > > with Dolby or DBX type noise reduction.
> > >
> > > When I first thought about it, I never imagined I'd be part of a team
> > > that would produce a better decoder for Dolby A encoded tapes than
> > > Dolby, but it's happening and humbling... So, it is a good idea to save
> > > as much raw data as possible because who knows what else will come
> along.
> > >
> > > Plangent is wonderful, but a bit problematic as it is still
> inconvenient
> > > to properly archive the bias, but that's another story, and I think in
> > > the long run it would be good if we could do that.
> > >
> > > MY QUESTION is: Are there any standards or recommendations that say
> > > "keep the raw undecoded copy as well as keeping the decoded copy?
> > >
> > > It's for a paper that Federica and I are writing.
> > >
> > > Thanks!
> > >
> > > Cheers,
> > >
> > > Richard
> > >
> >
> > --
> > Richard L. Hess                  email: [log in to unmask]
> > Aurora, Ontario, Canada                            647 479 2800
> > http://www.richardhess.com/tape/contact.htm
> > Quality tape transfers -- even from hard-to-play tapes.
> >
> >
>


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