[ProAudio] FeralA - Recordings released encoded with Dolby A

[Bill Whitlock]

Certainly no disrespect intended here but, regarding setting azimuth, how does mono summing address gap scatter?  To the best of my knowledge, unless a multi-track head is made from a single ferrite block (which most 64x duplicator heads are), gaps are not perfectly co-linear. Seems to me that peak HF output (optimum azimuth) may not occur at the same setting as an "in-phase" between tracks setting (they were often wildly different in consumer cassette players). And if you adjust for this phase condition at the edge tracks of a multi-track head, how can you be assured that tracks in between are optimized?  Has head azimuth scatter and co-linear scatter improved that much since the late 80s (when I was involved with this stuff at Capitol)?
Bill WhitlockWhitlock ConsultingVentura, CA


-----Original Message-----
From: Bob Katz via ProAudio <proaudio at bach.pgm.com>
To: proaudio <proaudio at bach.pgm.com>
Sent: Tue, Feb 11, 2020 9:21 am
Subject: Re: [ProAudio] FeralA - Recordings released encoded with Dolby A

 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 
 
 
 
 _______________________________________________ 
 ProAudio mailing list 
 ProAudio at bach.pgm.com 
 http://bach.pgm.com/mailman/listinfo/proaudio 
 
 -- 
 

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

No trees were killed in the sending of this message. However a large number
of electrons were terribly inconvenienced.
  _______________________________________________
ProAudio mailing list
ProAudio at bach.pgm.com
http://bach.pgm.com/mailman/listinfo/proaudio
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://bach.pgm.com/pipermail/proaudio/attachments/20200211/f1485b98/attachment-0001.html>