[ProAudio] FeralA - Recordings released encoded with Dolby A

Tue Feb 11 10:41:18 EST 2020

How can you tell if it was tilt of the head or delay caused by 
non-colinear head gaps that's causing the issue?

Bob

On 2/11/20 1:00 PM, James Perrett via ProAudio wrote:
> With regard to setting the azimuth by summing to mono and adjusting 
> for maximum hf - I've heard people say that there could be a problem 
> if the head gaps on each track are not in line with each other. I've 
> not experienced this myself as I've found that setting the azimuth 
> with a 15kHz tone using just one channel matches the mono sum method 
> well on the machines that I use but I guess some manufacturers made 
> their heads more precisely than others. Have others experienced head 
> gaps being out of line with each other?
>
> On Tue, 11 Feb 2020 at 17:21, Bob Katz via ProAudio 
> <proaudio at bach.pgm.com <mailto:proaudio at bach.pgm.com>> wrote:
>
>     Here are three responses to three different subjects that have
>     expanded from the original topic!
>
>     I. There are so many ways that test tones at the head of a tape
>     could be different from the audio on the tape. In the old days in
>     some studios I saw some visiting engineers lay down test tones
>     after the fact, on a different machine than was used for the
>     mixdown, as if that would help the situation.
>
>     We transfer engineers have developed a spidey sense and often
>     check and recheck the content to ensure it has not changed from
>     cut to cut. On most machines, before making the transfer for a new
>     cut, you can put your finger on the side of the tape to tilt it
>     slightly, while listening in mono to ensure the azimuth has not
>     drifted, and then transfer the new cut.
>
>     II. As for Bob O's comment against the practice of doing elevated
>     dolby level, I agree there was a standard for 185, but as people
>     started to use elevated levels as high as 6 dB over 185, I was
>     seriously concerned about running out of headroom in the Dolby
>     gear if standard dolby level was used, and so as a practice, I see
>     less harm in using an elevated dolby level than to overload the
>     Dolby processor with too hot audio. I always recorded dolby tone
>     as well as 1 kHz @  VU. The Dolby 361 meters, as Richard
>     mentioned, were notoriously inaccurate, I would put a sharpie mark
>     on the real dolby level on the meter, for what it was worth. There
>     was a Dolby tester that could be used for accuracy of the dolby
>     tone or I believe a test point that could be checked.
>
>     III. Dear John:
>
>     So you set azimuth by looking at the bias. Are you looking at two
>     channels of bias? And how is this superior to the tried and true
>     method of mono-summing the left and right audio channel and
>     adjusting for maximum high frequency response, also checking by
>     inverting the polarity of one and going for a minimum as a cross
>     check?
>
>
>     Best wishes,
>
>
>
>     Bob
>
>     On 2/9/20 4:32 PM, John Chester via ProAudio wrote:
>>     On 2/9/20 3:56 PM, Richard L. Hess via ProAudio wrote:
>>
>>>     Also, a funny story, the tones at the head of that master tape
>>>     caused Alan a bit of a challenge...the azimuth of the tone
>>>     didn't match the azimuth of the audio!
>>
>>
>>     Been there, seen that.  An assembled album master may contain
>>     cuts that were recorded on different machines, and sometimes even
>>     in different studios.  This becomes really obvious when I'm doing
>>     Plangent transfers.  I can see when the bias frequency and
>>     flutter profile change, and I set azimuth on each cut by looking
>>     at the bias.  I have seen a master where the head tones were
>>     recorded on a different machine which didn't match *any* of the
>>     music.
>>
>>     When the album master is Dolby encoded, and several different
>>     machines were used for mixing, I can't believe that the Dolby
>>     setup on all of those different machines perfectly matches the
>>     head tones.  Fortunately the tape with the head tones recorded on
>>     a completely different machine wasn't Dolby.....
>>
>>     -- John Chester
>>
>>
>>
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>     -- 
>
>     If you want good sound on your album, come to Bob Katz
>     407-831-0233 DIGITAL DOMAIN MASTERING STUDIO Author: *Mastering
>     Audio* Digital Domain Website <https://www.digido.com/> No trees
>     were killed in the sending of this message. However a large number
>     of electrons were terribly inconvenienced.
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>
>
> -- 
> **********************************************************************
> *       James Perrett
> *       JRP Music Services, Hampshire, U.K.
> *       Audio Mastering, Restoration, Recording and Consultancy
> *       Phone +44 (0) 777 600 6107
> * e-mail james at jrpmusic.net <mailto:james at jrpmusic.net>
> * http://www.jrpmusic.net
> **********************************************************************
>
>
>
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-- 

If you want good sound on your album, come to Bob Katz 407-831-0233 
DIGITAL DOMAIN MASTERING STUDIO Author: *Mastering Audio* Digital Domain 
Website <https://www.digido.com/> No trees were killed in the sending of 
this message. However a large number of electrons were terribly 
inconvenienced.

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