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Author Topic: Film sound - history and technical details Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 07-22-2004 06:12 AM                        I had pictured the Colortek system as using the whole width of the available space for just one channel, but then have one channel in each of the color layers which would be read separately using color filters. Apparently I was mistaken!  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 07-22-2004 06:54 PM                        For info, chapter and verse on Fantasound can be found in W.E. Garity & J.N.A. Hawkins, 'Fantasound', J/SMPE vol. 37 (August 1941), pp. 127-146.  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 07-30-2004 04:37 PM                     Some more questions, as I've been doing more reading and more thinking. If you get a print with an Academy mono (Format 01) track, would it be necessary to play it in Format 01, or could you use 04 or 05? Since the two tracks are identical, I don't see that there would be any issues with improper surrounds being decoded. Everything should be sent to the front speakers. The only issue I could think of would be improper noise reduction. If the track was not recorded with any NR, would there be any adverse effects if you were to play it back with NR (04 or 05)? My next question pertains to Format 03. My theater has CP55's. I read the enitre instillation manual. It says that most Dolby Stero prints were (and are) mixed with a surround channel, except for a very few of the early ones. In the troubleshooting section, it says that if you are having problems playing one of these early prints in Format 04 (if improper surronds are being decoded), to play it in 03, which will eliminate the surrounds. So what do you do if you get one of these prints and you have a CP65 or a 650?, which do not include Format 03? (The CP500 includes Format 03 as one of the formats you can choose when assigning custom formats. Form some reason, at least according to the manual, the 650 does not. Anyone know why?)  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 07-30-2004 05:21 PM                     Regarding older mono tracks in the USA; they where recorded with the "academy curve" which would effect playback quality. Mono track azimuth may not be perfect and may have undesireable on the surrounds.  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 07-30-2004 05:39 PM                        03 wasn't used very much. The only film which I know for sure was released in 03-encoded prints was Lizstomania. Vaguely related to which, I found that if you get a variable density track with less than ideal contrast (i.e. it's flat, and so there's a hell of a lot of ground noise playing it normally), playing it in 02 does an amazing job in boosting the s/n. The Dolby manuals threaten the death penalty for using 02 on anything other than a noise reduction-encoded mono VA print, but my purely subjective opinion is that in many cases, it makes density tracks sound a lot clearer.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 07-30-2004 05:51 PM                    In addition the level would be too high although obviously you could bring the fader down. Dolby prints are recorded at a slightly lower level than mono as they trade off some of the improved noise floor for more headroom (by keeping the average level lower there is more room for loud sounds like explosions etc. without clipping--the modulation on the track can only get so large). A is lower than mono. SR is lower still. If you ever did encounter a Dolby A - No Surround print (sorry if I skip over the format numbers; it's just plain silly) just play it in Dolby A and turn off the surround amp(s). (Unless of course you get a chance to audition it and find it sounds better with that bit of ambience in the surrounds).  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 07-30-2004 06:00 PM                     What is Format 02? I've never seen this described or even mentioned in any of the Dolby manuals I've read.  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 07-30-2004 07:58 PM                    Dolby Mono (A-Type) High fidelity (wide range, not Academy-curve limited) with Dolby A-Type noise reduction but not stereo. So...noise reduction on....Academy filter off...and matrix should be told to sum Lt & Rt into C. This is the original Dolby optical sound format although I believe it was more a UK and possibly Canadian thing than US. Dolby Model 364 contained a single Cat.22 A-type NR card while Model E2 contained a single Cat.64 house EQ card. The original Cat.64's also held a separate circuit which offered an adjustable HF gain like you now have on CP preamp cards...sometimes called slit loss correction. So the signal could go through that before going to the 364 for NR then back to the E2 for house EQ. These are both 1 rack unit high boxes and many found use later on as add-ons to the CP100 system. Woody Allen still uses the SR version of this format.  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 07-30-2004 08:03 PM                     So essentially it's a track with A-type NR applied, but the mix is mono, correct? How many titles used this format? Why is Format 01 included on modern processors, but 02 isn't? When playing current Woody Allen titles, should they be played in Format 05? It doesn't really matter what the mix is (mono, stereo), as long as the correct noise reduction format is applied, right?  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 07-30-2004 08:12 PM                    According to the Larry Blake book about 10 films were released in Dolby Mono. That was from a 1981 article and obviously doesn't count subsequent titles of which Allen may be the only known user but there could be others. Yes, play the current films in SR (or digital of course). The NR, level, and Academy filter OFF is the most important thing. If things are in reasonably good adjustment the matrix will steer sound to the C channel just fine. If there's a problem you can always kill the other amps.  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 08-01-2004 12:18 PM                        I don't quite understand if we are talking about a currently released title released with SR encoding, why it would be necessary to make any mention at all as to whether the print was mixed MONO or STEREO. Wouldn't it make more sense to avoid confusion in the booth by projectionists who are going to see the word MONO in the leader and go "DUH"? Seems it would make more sense to simply let it play in the standard SR stereo format. The processor in the stereo + surround mode will care not a wit if the audio mix happens to be mono. If the A-chain is correctly aligned, it should play a stereo track with mono content without incident, with the L & R summed to the center and with hardly anything coming from the left and right and nothing in the surrounds. If the system is slightly out of alignment and stuff is bleeding into the surrounds, as you said, those amps could always be turned off if needed (or better yet, call in a service tech to realign the system). You could even turn off the L & R channels if you absolutely have to, although a mono signal coming out of all 3 screen channels has never sounded objectionable, IMHO. But in a well calibrated system, this should not even be an issue. Is it really relevant to the projectionist to know if what is on the soundtrack is recorded in mono or stereo? Or am in missing something here? I just think you would be asking for trouble by saying it has to play in SR but in MONO and without the Academy curve (if it is mixed in MONO, it will de facto play back as mono); the Academy curve is would become a real issue in older processors. The CP50, and 55 don't have that format configuration readily available, correct?  |  IP: Logged Ken Lackner Phenomenal Film Handler Posts: 1907 From: Atlanta, GA, USA Registered: Sep 2001 posted 08-01-2004 01:34 PM                     So Woody Allen films are technically SR, right?  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 08-01-2004 02:24 PM                        The last one I showed (Small Time Crooks) was, and it also had Dolby digital through the centre channel only (i.e. all the others carried no signal, so you might as well turn their power amps off during the show).  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 08-02-2004 03:12 AM                        Well, why bother turning of the amps at all? Surely not to save electricity. Besides, if you are playing digital, there is no chance of errant bleed into other channels. If there is no signal recording in all but the center channel, the other channels will just be silent, no worry about bleed. On the other hand, turning off amps would be quite problematic when the trailers are run. With SR, there could be a slight bleed into the surrounds, but as I said, if your system is properly aligned, that should not be a problem -- the delay masks that.  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 08-02-2004 04:10 AM                        In my case, it was simply to cut down on the heat being kicked out by their fans in what was a very hot booth.  |  IP: Logged

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