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<p><font face="Arial">Hi Richard,</font></p>
<p><font face="Arial">Of the mastering houses that I worked with
during the 1970's (& I worked with several), I never saw or
heard of a reference document regarding noise reduction. Both
Scott Dorsey & Bob Olhsson referred to using Dolby A as an
effect. Back in the day, I generally avoided noise reduction
when recording to multitrack tape. I could hear the difference
or, at least, I thought I could. That said, I used to routinely
encode travel cassettes & then play them un-decoded in the
car because the extra HF would help cut through the road noise.</font></p>
<p><font face="Arial">Regards,</font></p>
<p><font face="Arial">Corey</font><br>
</p>
<pre class="moz-signature" cols="72">Corey Bailey Audio Engineering
<a class="moz-txt-link-abbreviated" href="http://www.baileyzone.net">www.baileyzone.net</a></pre>
<div class="moz-cite-prefix">On 2/9/2020 9:32 AM, Richard L. Hess
via ProAudio wrote:<br>
</div>
<blockquote type="cite"
cite="mid:a9a56dad-11e1-d84d-4bbe-efb9b1e0ba73@richardhess.com">My
colleague in the software decoder for recordings made with Dolby A
noise reduction has been very interested in commercial releases
that appear encoded.
<br>
<br>
He has spent a good deal of time researching this. Thankfully,
he's spared me most of the listening, but he's getting very good
support from some online audiophiles, including one, I think, who
writes for The Absolute Sound or something like that. I can hear
the difference in the samples he sent me.
<br>
<br>
The premise is that many albums were released without proper Dolby
A decoding.
<br>
<br>
I've been told this is the case for a few albums, including at
least one recent re-release which was mixed undecoded from the
Dolby A multitrack.
<br>
<br>
What makes this more interesting is that he's finding a handful of
EQ curves need to be applied to the recording prior to decoding.
<br>
<br>
He has also found that many/most of these decode better as
Sum/Difference (or MS).
<br>
<br>
He thinks that there might have been a reference document in the
mastering industry--it is that consistent.
<br>
<br>
Does anyone know anything about this, or is it just happenstance?
<br>
<br>
We don't think it's a common failure mode of old decoders--but it
appears intentional.
<br>
<br>
I know this sounds crazy, but there seems to be experimental
support for this and the consistency of it is interesting.
<br>
<br>
Does anyone know of any processes that were used in mastering back
in the 70s that might create this. We don't think it's the Aphex
Aural Exciter--that is a different kind of annoyance for my
colleague. He has done some experimenting on a De-Exciter.
<br>
<br>
Example artists are Linda Ronstadt, Olivia Newton John, and to
some extent Abba.
<br>
<br>
One of the reasons I've not attempted to shut down his FeralA
experiments is that it has led to better finessing of the
parameters and better decoding of real Dolby A recordings.
<br>
<br>
Thanks!
<br>
<br>
Cheers,
<br>
<br>
Richard
<br>
<br>
</blockquote>
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