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» Film-Tech Forum   » Operations   » Film Handlers' Forum   » 70MM Magnetic Surround Channels (Page 1)

 
This topic comprises 2 pages: 1  2 
 
Author Topic: 70MM Magnetic Surround Channels
Aron Toplitsky
Film Handler

Posts: 93
From: Gardena, CA, USA
Registered: May 2012


 - posted 03-10-2017 08:09 PM      Profile for Aron Toplitsky   Email Aron Toplitsky   Send New Private Message       Edit/Delete Post 
Is it just me or did it seem like the surrounds were mixed louder for 70MM blow ups in the 80s? For years I've felt like digital sound for the average film and the DTS tracks for the more recent 70MM presentations, lacked a surround presence.

Is it possible the nature of the magnetic soundtrack gave a better surround presentation? Thoughts anyone?

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Terry Monohan
Master Film Handler

Posts: 260
From: San Francisco CA USA
Registered: May 2014


 - posted 03-11-2017 12:26 AM      Profile for Terry Monohan   Email Terry Monohan   Send New Private Message       Edit/Delete Post 
Yes I liked the old mag surround sound, It was on at a good level and had a little high end hiss to it very crisp at times. Most of the digital cinemas today the people in charge of the no projectionist booths have turned the surrounds way down as the old people complain they are on to heavy.Then they have the nerve to tell me that is the way the producers mixed the sound. What is strange seems like some chains have the previews turned up or they were mixed that way and when the main feature comes on all the speakers stage and surrounds are sort of flat and don't have the punch the previews did. I miss 70mm mag stereo sound. It was so powerful It blew out many of the surround speaker cones when they played 'Top Gun' at the old Cinerama Theatre in San Diego CA many years ago.

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Mark Gulbrandsen
Resident Trollmaster

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From: Bountiful, Utah
Registered: Jun 99


 - posted 03-11-2017 08:44 AM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
I think it all just depends on what the re-recording mixers and Director wanted to achieve. It's really their choice.

Mark

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 11986
From: Annapolis, MD
Registered: Dec 1999


 - posted 03-11-2017 12:30 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Here's the scoop. Most people with home theatres like the surround louder than intended. I deal with it all of the time. Additionally, in the 80s, it is quite possible that the theatre you went to may have turn the surrounds up a bit (happened all of the time). I've ever hear the line "I paid for them, I want to hear them).

For most of the 80s and prior, surrounds were just mono. They may have seemed louder since ALL were playing if any of them were. In fact, the legacy of the mono surround channel plagues the professional CINEMA market to this day, despite DCPs as being defined as a 5.1 soundtrack, minimum.

When stereo surrounds came out in the late 70s, they had to deal with cinemas (and movies) that had a mix of mono and stereo surrounds. So those cinema processors with stereo surrounds had their surrounds turned down 3dB per side. To which you think "Aha! I knew they turned them down in modern times!" Wrong, when Ls/Rs are playing together (e.g. mono surround material), they acoustically sum together to bring the level back up the 3dB that was removed. So, if you had a mono surround source and played it in a 5.1 theatre or 4.1 theatre, the surround level as measured is identical. When Surround EX came out in 99 (blech), same problem. The surround level had to remain the same regardless of auditorium it played in so if you played the same movie in a 4.1, 5.1 or 6.1 theatre, the measured surround level remains the same. Now, inferior EX decoders (which is an odd statement since EX was an inferior format, in my opinion) would get the levels wrong and emphasize the rear surrounds instead of have them be uniform with the rest of the array. Remember, in that same room, regardless if optical (mono surrounds), digital (stereo surrounds), or EX (sort of 3-channel surrounds), the levels should not go up/down based on what mode you had the processor in.

Now with 7.1, we cut the channel into quarters but the same rules apply Ls/BSl should play at the same level as just Ls in a 5.1 theatre. Thus, if you had all four 7.1 surround channels playing the same content as a mono surround theatre, the surround level should be identical.

What I find absurd is with DCPs, we had the opportunity to make a clean break from the mono-surround legacy. Furthermore, we had the opportunity to also get rid of the sound processor being responsible for level matching (which most techs don't seem to pay attention to). In my opinion, the people recording the movie should lay the track down without any compensation in the processor. Thus, while a 7.1 system would need to adjust its levels for a 5.1 movie, a 5.1 system playing a 5.1 movie (the new standard) should have played everything without any compensations. That is, in a typical processor where reference is 85dBc (at -20dBFS, "7", "0dB) it should have been that the surrounds were set to 85dBc like the stage channels. Instead, we had to bow to the legacy of pre-compensating of 82dBc/side so they would sum to 85dBc if played in unison. For the brief period where there was an overlap of film and digital, we have forever forced the industry to cater to a dead format (mono surrounds).

Again, I get the low-surround level complaint a fair bit but in truth, they are playing at the level the people that recorded it intended. I've done enough studio screenings to know.

Another factor, if you have crappy stage channels that are hard on the ears, you will tend to turn your fader down and with that, the surrounds. I've found that with better speakers/acoustics, the volume levels can play higher without discomfort and the surrounds have a much better presence.

Lastly, in the 80s, surrounds were typically not EQed or were minimally EQed so you may have had some extra bright sounding speakers that made themselves better known. I for one, subscribe to the belief that surrounds should not have the same ISO2969 rolloff due to their proximity to the listener and roll them much less, which does tend to give them more presence.

Remember too, in the 80s, you had the effects of a wide range of decoding equipment affecting your interpretation of the soundtrack. With DCPs, you are listening to PCM tracks with minimal processing. It should be, in most every respect, be a more faithful version of the original track.

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Bobby Henderson
"Ask me about Trajan."

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From: Lawton, OK, USA
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 - posted 03-11-2017 02:54 PM      Profile for Bobby Henderson   Email Bobby Henderson   Send New Private Message       Edit/Delete Post 
Another really big difference with 70mm magnetic surround:
Such audio tracks were almost always played in standard sloped auditoriums with far lower ceilings and far less cubic air space to manipulate.

Modern theaters are almost always configured with stadium seating. Such rooms have an entirely different audio character than the mildly sloped auditoriums that started disappearing 20+ years ago. It takes a substantially more powerful sound system to deliver tight, punchy, startling dynamics and sub-bass powerful enough to rumble the air in your chest. Most theater chains aren't willing to spend the money on speakers and amplifiers needed to do that. The surround speakers in stadium seated theaters are typically the same tiny cabinets installed in old mild sloped theaters. The problem is the ceiling is a whole lot taller and the room shape is very different and very uneven. If you want to hear the surrounds at all you have to sit way back in highest rear-most rows of the auditorium. This is especially true for ceiling mounted surrounds for use with new formats like Dolby Atmos.

I think movie theater chains need to re-think how they design stadium seated auditoriums. For the longest time I've thought they should have a far milder slope, just steep enough to let you see over the heads of people in the next row, rather than have their heads on levels lower than your knee caps. The ceilings wouldn't need to be so damned high. It would probably be easier and cheaper to configure effective surround systems for such rooms. And next gen formats like Atmos would be far more effective in their surround coverage.

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Stephan Shelley
Jedi Master Film Handler

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From: castro valley, CA, usa
Registered: Nov 2014


 - posted 03-11-2017 03:58 PM      Profile for Stephan Shelley   Email Stephan Shelley   Send New Private Message       Edit/Delete Post 
Not so sure about that. A lot of theatres that showed 70mm back in the day were balcony or rear stadium setup. The Coronet in SF was main floor sloped and a large lodge stadium section behind it that went up over the lobby. This was a the house setup for Todd-A-O and Around the World in 80 Days. All of these had 30-40 foot ceilings and were wide houses to accommodate 70-90 foot screens.

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Michael Cornish
Film Handler

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From: Cincinnati, Ohio, USA
Registered: Sep 2011


 - posted 03-11-2017 07:50 PM      Profile for Michael Cornish   Email Michael Cornish   Send New Private Message       Edit/Delete Post 
I remember running Die Hard in 70mm at the old Kenwood twin cinemas in Cincinnati. On the days that I had usher shifts when taking trash out to the dumpster the ground would shake outside during the opening scene.It was the first time the Century JJ mag pick ups had been used since the 60's according to our chain techie.After the first weekend he had to order a new pick up with gold contacts the original one gave up the ship from sitting dormant for so many years.

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Bobby Henderson
"Ask me about Trajan."

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From: Lawton, OK, USA
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 - posted 03-11-2017 09:10 PM      Profile for Bobby Henderson   Email Bobby Henderson   Send New Private Message       Edit/Delete Post 
quote: Stephan Shelley
Not so sure about that. A lot of theatres that showed 70mm back in the day were balcony or rear stadium setup. The Coronet in SF was main floor sloped and a large lodge stadium section behind it that went up over the lobby. This was a the house setup for Todd-A-O and Around the World in 80 Days. All of these had 30-40 foot ceilings and were wide houses to accommodate 70-90 foot screens.
I'm going on my experiences from 1980's and 1990's, having visited many 70mm equipped theaters in New York City, Washington, Atlanta and Dallas. Very few of those theaters had balconies. The best sounding ones had no balconies, especially the ones with high seating counts (like Loews Astor Plaza and the Ziegfeld in NYC or Northpark #1 in Dallas).

I've never heard a stadium seated theater have dynamics that punched the chest quite like that of the Northpark theater in Dallas. IMAX-branded theaters can get plenty loud and even really punchy with bass, but the EQ often just plain sucks. And that's really where a theater like Northpark shined.

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Stephan Shelley
Jedi Master Film Handler

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From: castro valley, CA, usa
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 - posted 03-11-2017 09:50 PM      Profile for Stephan Shelley   Email Stephan Shelley   Send New Private Message       Edit/Delete Post 
Even the Northpoint in SF had an 89 foot screen sloped main floor only seated around 980 had at least 30 ft ceilings and 100 feet wide a big space.This theatre was built around the era you are talking about.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 11986
From: Annapolis, MD
Registered: Dec 1999


 - posted 03-12-2017 09:52 AM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
I find you analysis, Bobby, wrong. The surrounds have always followed the slope of the floor so regardless of slope floor or stadium riser; the distance between the surround speaker and listener is about the same. The size of the auditoriums has also always been a variable with the palaces of yesteryear being VERY wide but the early multiplexes being rather narrow. To this day, you still get a mix of situations.

While yes, as the risers approach the rear, it is possible for the rear surrounds to get VERY close to the listener, that would be a bad theatre design. Remember, speakers have a radiation pattern and they are "aimed" to cover the listening area, without regard to the room size. Surrounds tend to be primarily direct response devices and the use of many of them makes them diffuse. This is contrary to stage speakers where you want a direct response (1st arrival to be predominate) but often have to contend with the acoustics of the auditorium and strike the right balance of reverberation and 1st arrival to maintain intelligibility.

A typical stage horn has a 40-degree vertical coverage angle. In a slope floor theatre, you are going to point this further down to put that coverage on the seating area, however older theatres tend to be deeper, which raises the horn a bit. In a stadium theatre, the theatre is typically more shallow but more tall so you will have that horn pointing higher up to again, keep its coverage over the seating area. Now, ideally, in yesteryear we would have used variable intensity horns like the old Altec VIR but I don't know of anyone that did. We do use an outgrowth of that horn in some surround applications (under balcony and balcony side surrounds, the EVI-28).

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Terry Monohan
Master Film Handler

Posts: 260
From: San Francisco CA USA
Registered: May 2014


 - posted 03-12-2017 01:49 PM      Profile for Terry Monohan   Email Terry Monohan   Send New Private Message       Edit/Delete Post 
Thanks Steve for your notes about surround sound. If any of you live in SF Bay Area check out the stereo split surround level in large theatre #1 at Oakland's Grand Lake Theatre for the 70mmn film showing 'Kong'. Stephan,your projection work was spot on, the 70mm blow up film looked so hot last night, not a scratch or piece of dirt on the print. The best part of this new Kong 70mm film was the sound mix at your cinema in Oakland and how It sounded in the large downstairs auditorium. Sounded like I heard 4 different channels coming out of the surrounds at a decent level. The sound mixers did a great job on 'Kong' and best of all Stephan had the surround speakers turned up at a good level that It wrapped the whole movie palace into the story coming from the screen. Go see 'Kong' and listen to some of the best surround stereo split mix you will ever find in a movie in the last 10 years. 5.1 /7.1 or more this new movie had all the surround speaker sounds working for music and jungle sounds plus many other stereo effects,the movie was not that bad either. The new red LED lights in the cinema added to the feel of the film, glad they stayed on at a low level all during the movie as most theatres turn all the effect auditorium lights off when the movie is on and you sit in the dark. Stephan can these effect lights be changed from time to time to lets say Blue or Green? Thanks again for a fun night out at a first class movie theatre and to see two sets of curtains that work brought joy to all my movie friends.

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Aron Toplitsky
Film Handler

Posts: 93
From: Gardena, CA, USA
Registered: May 2012


 - posted 03-22-2017 11:19 PM      Profile for Aron Toplitsky   Email Aron Toplitsky   Send New Private Message       Edit/Delete Post 
Thank you all for responding. Some very interesting responses.

Just when I complain about not hearing surrounds these days, I saw Skull Island this past Sunday and the surrounds were very active. I agree with Terry, it had some of the best split surround in years. I saw it in 70MM at the Arclight Hollywood and unfortunately the print had a scratch running along the left part of the frame for the entire movie. I was also a bit underwhelmed and disappointed by the LFE. It was active during some scenes, but not many. I still had a good time at the movies, the film was a lot better than expected.

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Martin Brooks
Jedi Master Film Handler

Posts: 775
From: Forest Hills, NY, USA
Registered: May 2002


 - posted 04-17-2017 08:13 PM      Profile for Martin Brooks   Author's Homepage   Email Martin Brooks   Send New Private Message       Edit/Delete Post 
quote: Bobby Henderson
The best sounding ones had no balconies, especially the ones with high seating counts (like Loews Astor Plaza and the Ziegfeld in NYC
And those theaters were far larger than today's theaters and had more volume to fill. The Ziegfeld (1150 seats) didn't have a balcony, but it did have stadium style seating in the rear.
 -

And it had very tall ceilings, probably one of the reasons it never had Atmos installed. The Astor Plaza (1530 seats) was a basement theater, so it did have lower ceilings and a moderate slope, but it was also very large.

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Mark Ogden
Jedi Master Film Handler

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From: Little Falls, N.J.
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 - posted 04-17-2017 09:21 PM      Profile for Mark Ogden   Email Mark Ogden   Send New Private Message       Edit/Delete Post 
Inside, the Ziegfeld was a beautiful theater. Putting in Atmos with all that crap hanging from the walls and ceiling would have been sacrilege. The room sounded just fine as it was.

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Paul Linfesty
Phenomenal Film Handler

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From: Bakersfield, CA, USA
Registered: Nov 1999


 - posted 04-17-2017 10:29 PM      Profile for Paul Linfesty   Email Paul Linfesty   Send New Private Message       Edit/Delete Post 
Ironically, the Ziegfeld's original surround speaker array was flush-mounted into the ceiling, a popular speaker location for many theatres of that era.

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