Re: dolby sr?

From: joe beres (email suppressed)
Date: Thu Aug 17 2006 - 09:21:01 PDT

I agree with Michelle here. I would request a mono mix without any
noise reduction.

I too worked a long time as a projectionist, and I may not be completely
clear on the subtleties of the Dolby NR in the mix process. My
understanding is that if you use Dolby NR in the mix, you would really
need to use it in playback as well.

In most 16mm situations, you will have one of two scenarios: 1. that you
are running your 16mm directly into into a mixer or amp or 2. that you
are running your 16mm into a Dolby (or other) Cinema sound processor.
In the first case, the sound is not being 'processed' for any noise
reduction whatsoever, and thus your track with the Dolby Noise Reduction
is not really being played back with the correct EQ curves. I would
expect a bit more muddiness and a deficit in some higher frequencies.
In the second case, the 16mm is likely being sent into one of the
processors 'non-sync' inputs, the same input you would use for a CD
Player for instance. Unless I am mistaken, any signal sent into that
port would not get processed either, thus skipping the noise reduction
card, and again reproducing the track in the same manner as the first
scenario. This is possibly untrue in case where a Cinema has one of the
more recent Dolby processor models that allow noise reduction and
processing to be applied to virtually any input. I think that this will
be found in very rare cases.

Also, I don't really know that there is an 'industry standard'
applicable to 16mm projection. I have certainly not heard of anything
in that regard, and this is the first I've heard of a lab introducing
Dolby SR standards to 16mm prints.

i hope this helps a bit. Good luck.

joe beres

Michelle Puetz wrote:
> 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
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> __________________________________________________________________
> For info on FrameWorks, contact Pip Chodorov at <email suppressed>.

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