Re: dolby sr?

From: Michelle Puetz (email suppressed)
Date: Thu Aug 17 2006 - 08:42:08 PDT

Hi Brittany,

It sounds to me like the optical guy at Magno is giving you a line. I
don't know that I can speak to the specifics of 16mm optical tracks /
dolby mixing & noise reduction, but I have worked professionally as a
projectionist for several years and maybe can help. Even though Dolby
claims that you can play back SR mixes through systems that are not
Dolby-equipped (systems that run source out to amplification and
speakers, instead of source out to Dolby processor, amplification,
speakers), I have found that doing so results in exactly what you
describe below.

I regularly project Dolby SR tracks on 35mm prints, and in theaters that
are equipped to handle both digital sound formats and analog formats,
the sound runs out of projectors, through a Dolby processor and
amplification system to speakers. It has always been my experience that
unless you play back in the appropriate format, your sound mix will be
muddy, flattened, and completely out of range. Again, this is all for
35mm, so I'm not sure if this is applicable to your situation - BUT,
when you play back a 35mm film that has been mixed Dolby SR in mono, it
sounds like what you are describing - muddy, mixed incorrectly, low-end
fall out.

Dolby SR (stands for spectral recording) was developed in the 80's to
provide greater range in sound mixes: to aid in noise-reduction, and to
allow low frequencies to be louder with less distortion and wider
frequency response. I know that this is difference for 16mm, but in
35mm optical tracks, in the area where the conventional 35mm mono track
is, the two optical tracks carry information for L/R stereo, in addition
to a center and surround channels. I think that this is what really
accounts for it's inability to be played back with no distortion without
a processor that can read Dolby SR. That said, Dolby claims that "35mm
optical soundtracks treated with Dolby SR not only sounded superb in
cinemas equipped with new Dolby SR processors, but also played back
satisfactorily in all cinemas". I don't find this to be the case.

I think that what you are dealing with is a Dolby noise-reduction mix,
right? In dealing with Dolby noise-reduction mixes, it has been my
experience that you need to play them back on a system that is equipped
to process a Dolby mix/signal. Even though Dolby claims the opposite,
this has been my experience. I can't actually believe that a 16mm track
would be mixed this way - is this really common?!??!?!?!?! I have
worked in theaters with equipment ranging from table-top 16mm running
through a home system to very high-end art house cinema theaters
equipped with brand-new technology, and I have only ever seen 16mm sound
running source out - processor (mono) - amplification - speakers. I
really think that you should call them back and ask for a standard mono
mix with no noise-reduction/Dolby mix. Where did you project the film?
Perhaps you could try to project it in a theater like HFA or the MFA
Boston to check to see what it would sound like in a theater that is
balanced for industry standard sound mixes and that plays 35mm via a
Dolby processor. This would be the real test - but then, the question
is, if it sounds good in those sorts of theatrical settings (which, I
really doubt will make a difference) and bad in smaller, 16mm only
analog sound systems - which setting do you think you'll be screening it
in more? They should really run an optical track with no noise
reduction so you can judge the difference yourself.

Good luck - I can't wait to see your new film!

Brittany Gravely wrote:

> hello,
> listening to my newly printed optical track, my sound masterer was
> bothered by a slight muddiness in parts. the optical guy at magno
> said it could be due to dolby sr noise reduction that is now
> "industry standard" and they run all of their optical tracks through
> it. he said if you're not projecting it in a theatre with that dolby
> option, it may sound occasionally bassier & possibly noisier on the
> high end, but it is supposed to result in a better dynamic range and
> less noise in optimal conditions.
> does anyone have any opinions, additional information on this? does
> everyone out there get this on their 16mm optical tracks? or does
> anyone not for any reason?
> thanks,
> brittany gravely
> __________________________________________________________________
> For info on FrameWorks, contact Pip Chodorov at <email suppressed>.

For info on FrameWorks, contact Pip Chodorov at <email suppressed>.