Film-Tech Forum ARCHIVE: simple stupid mag sound question

This is topic simple stupid mag sound question in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=008952

Posted by Peter Conheim (Member # 4196) on 10-12-2007, 02:25 PM:

I've just installed a Philips FP-20 projector with mag sound pickup, along with a Quad Eight pre-amp. My question: what is the channel configuration for the four tracks? In other words, is it:
1-L, 2-R, 3-Center, 4-effects, or... ??

Thanks,

PC

Posted by Steve Guttag (Member # 268) on 10-12-2007, 09:52 PM:

Starting from the outboard (closest to the operator when threaded) it is Left (1), Center (2), Surround (4), Right (3). That is, the surround channel is between the picture and the perforation on the inboard side. I believe if you download the Dolby MPU-1 manual (even if you aren't using it) it gives a picture of the track configuration.

Steve

Posted by Sam D. Chavez (Member # 1841) on 10-12-2007, 10:03 PM:

I disagree and can't believe I've forgotten this. It is left, center, surround, right from inside out. 1,2,4,3.

Hmm. Maybe Steve is right. This is his favorite format of all time.

Posted by Stephen Furley (Member # 1277) on 10-13-2007, 02:40 AM:

Surround is 3 and right is 4; you can tell because the surround stripe is narrower. Some people number them from the opposite edge though, I've got a feeling the Russians did.

Steve, I've got a feeling that you've listed the tracks in the order that they come on the film, rather than the L,C,R,S order that we normally think of them, but still swapped the numbers of 3 and 4, as if you'd listed them the other way, it you see what I mean.

Yes, the MPU-1 manual does show the track configurations for both 35mm and 70mm (Todd-AO format with five screen channels) formats.

Posted by Monte L Fullmer (Member # 2797) on 10-13-2007, 04:37 AM:

Yea, I've always thought, facing the base side of the film with the magnetic striping and soundtrack to the left and with the complete physical layout as such: Left,("FOX" sprockethole) Center,(optical track), Surround,("FOX" sprokethole) and Right.

I loved running mag - just one clean, strong sound compared to basic optical, which was long before anyone heard of Dolby...

Posted by Louis Bornwasser (Member # 3063) on 10-13-2007, 08:39 AM:

Ah, yess! "Poor-man's 70mm" strikes again!!

Also my favorite format. Cheaper than 70, but with 80% of the benefits.

When I did a lot of premieres (mono) I would order a fox-hole print and have it sounded mono on all four tracks. In early platter booths, this avoided picture & track issues, not excluding the booth op's heart attack hen he found out about picture & track. Louis

Posted by Steve Guttag (Member # 268) on 10-13-2007, 09:47 AM:

No, my post was correct. Surround is always channel 4 in a 4-track system but the order on the film is 1, 2, 4, 3 due to surround getting the thinner track. A common mistake is that the thin track is not on the optical soundtrack side. It is Center, a full-width track, that covers one of the optical tracks in a mag-optical print.

Whereas CinemaScope with 4-track magnetic premiered before the modern 70mm format (ToddAO) it wasn't a poor-man's 70mm. 70mm was a rich-man's 4-track [Wink]

Posted by Mark Gulbrandsen (Member # 72) on 10-13-2007, 10:28 AM:

Steve is correct on the 4 track layout. 4 track saw much inginuity put behind it in its early years including the use of Perspecta on the surround channel in at least one feature. Lets just say thats where the EX idea came from.

Posted by Monte L Fullmer (Member # 2797) on 10-13-2007, 01:35 PM:

Remember when FOX released "Damnation Alley" back in 1976 in an unusual mag format which introduced L/R surrounds on a 35mm mag print? It had a name to it, but can't remember what it was..for it was such an oddity of a release.

They took out the conventional front L/R tracks and put them in as L/R surround information and the actual surround track became center surround....Thus, a print with discrete channel information. The house had one speaker per each channel.

This was the only film release that I know of that did this mag arrangement.

Posted by Sam D. Chavez (Member # 1841) on 10-13-2007, 03:43 PM:

I am humbled to admit Steve is right and I am wrong.

That was my initial recollection and then I checked with someone we all know who talked me into his version.

There's always a first time. [Wink]

Posted by Stephen Furley (Member # 1277) on 10-13-2007, 04:58 PM:

Sorry Steve; I mis-understood what you were saying.

quote: Mark Gulbrandsen
4 track saw much inginuity put behind it in its early years including the use of Perspecta on the surround channel in at least one feature.

Mark, I assume you are talking about 'Around the World in 80 Days'; That's the only film that I've ever heard of doing this. If you know of any others I'd be very interested to hear about it.

The use of Perspecta on the surround of the 4-track prints is fairly well known, and I've seen evidence which while not absolutely conclusive, strongly suggests that it was also used with the infamous 34mm print of this title which ran in London. However, there seems to be general agreement that this was not used on the 6-track Todd-AO version. Do you have any idea why this was?

A couple of years ago there were rumors that a 4-track print with Perspecta surrounds existed, and that a screening of it was a possibility, but I've heard nothing since.

Posted by Bernard Tonks (Member # 809) on 10-13-2007, 05:58 PM:

CINESTAGE 34mm.

"Around the World in 80 Days" originally opened in London, England in 1957.

Cinestage.

Todd-AO.

Posted by Mark Lensenmayer (Member # 134) on 10-13-2007, 06:22 PM:

Damnation Alley was in Sound 360.

I saw this process in two different theatres, and it sounded very nice. They used rather large surround speakers, at least much larger than the very small ones they used in those days.

Posted by Gordon McLeod (Member # 33) on 10-13-2007, 07:57 PM:

Also Tommy used three of the mag channels with DBX and a QS matrix to have left and right surround channels

Posted by Sam D. Chavez (Member # 1841) on 10-13-2007, 08:51 PM:

The speakers I saw used were Altec 604 Coaxial speakers. The idea was to have a very directional surround unlike the Dolby surround idea.

This was the only show in this "format" to my knowledge.

Posted by Louis Bornwasser (Member # 3063) on 10-13-2007, 09:58 PM:

Sam, you are correct about only one film made in Sound 360. Fox thought this was the better film; booked into the "large house. Star Wars & Dolby was thought to be an also ran. One died; one survived! Louis

Posted by Monte L Fullmer (Member # 2797) on 10-14-2007, 02:18 AM:

quote: Gordon McLeod
Also Tommy used three of the mag channels with DBX and a QS matrix to have left and right surround channels

...wasn't that format called "Quintraphonic Sound" - with the three screen speakers and the L/R surrounds?

Another one of those one-time formats that came and went.

Yea, in that showing of "Damnation Alley" I remember those very large surrounds installed on each wall. True, it actually sounded real good (yes, it was the spring of 1977 when that movie came out for I remember seeing pre-release one-sheets of Fox's next sci-fi feature called "Star Wars' ...in that theatre that I attended this screening), but the movie was a terry campy and thinly made. Comes to mind that FOX was trying to capitalize on Universal's "Sensurround", but prob found out to convert a lot of the cinemas to this '360' format wasn't the best idea.

Posted by Frank Angel (Member # 248) on 10-14-2007, 04:32 AM:

TOMMY was billed as "Quintaphonic Sound" and it was designed by John Mosley who had worked on multichannel optical sound using a multicolor soundtrack (was it called Kinetek?). Thing about the TOMMY release -- try to find a print; they were very hard to come by, at least here in the states. Evidently whatever inventory they had of them were concentrated in the UK. We could only get a straight 4trk.

We also ran another non-standard 4trk mag print -- LADIES AND GENTLEMEN, THE ROLLING STONES. It had split surrounds, using what was normally the center channel as one of the surround sides, the normal surround track being the other side. The center channel was a sum of L&R. It worked fairly well, and in our house which does have point-source split surrounds -- two JBL double bins in either corner -- it was very impressive indeed.

The center sum was a different story -- dialogue was indistinct and you got the sense that it "wandered" depending on the seat and even how you moved your head. It would have been helped by Dolby's "smart" processing that boosts center information that is identical in L & R, so dialogue is dominat in the center. Be that as it may, the mag made it sound spectacular over what you were used to hearing over optical mono.

Given that our system uses a patchbay to route all signals, reconfiguring it for this feature was easy. Not so sure how easy it would have been in other places.

There was another maverick mag configuration that we ran into -- I don't know if it even had a name, but when Samuel Goldwin bought the rights to SOUTH PACIFIC and OKLAHOMA! in the 80s, they struck 3 trk mag prints on standard sprocket stock. This gave them room for L, C, R but no surround. It also made the heads ride ever so slightly on the sprocket holes themselves which was not a good thing for the heads, I would imagine. We only played both these titles for 4 shows each, so I wouldn't think it could damage the heads for that short time, but it probably would not be a good idea to play these prints for weeks on end. They did look excellent image-wise and the screen channels were mag and duly robust and impressive but I really did miss the surrounds.

To compensate, I took one of our recording studio Sansui QS Vario matrix decoders which we used to record and play back Quadraphonic sound in the studio and rigged that in the booth to feed that the L & R screen channels and outputed the Sansui to the L & R rear channels.

The matrix extracted out-of-phase ambience from the L & R fronts and I would manually sneak that up into the surrounds during the musical numbers in the films. L & R did have dialogue, but it was under the music and the matix totally eliminated it, so we didn't get vocals in the surrounds just music -- whatever the matrix found out-of-phase. I only brought this up very gently, just so there was a hint of it behind the audience. The exception was the very long ballet sequence in OKLAHOMA, which sounded spectacular with it playing equal volume in the surrounds. The orchestra was 360 around the audience.

For CAROUSEL, we only could get a mono print. DAMN Fox -- they PROMISED a mag print -- sent me one which indeed SAID mag on the can, but turned out to only be mono. I was so angry (we had advertised stereo) that I was determined I was going to get SOME surround, so I went into the studio with a christmas ornament -- a bundle of little glass bells on ribbons. They made a perfect sound of the glass stars that tinkle in the "heaven" sequences in the film. I recorded them {in stereo} and then during the run of the film, I had my assistant playback the stereo "bells" recording in the split surrounds. It was very effective -- just the subtle sound of the "stars" almost identical to the stars sound in the screen channel, but all around the theatre.

So what if my collegues pointed fingers and whispered and called me crazy -- it's all for the audience!

Posted by Louis Bornwasser (Member # 3063) on 10-14-2007, 11:15 AM:

As regards the "3 track" prints: the pressure on film is orders-of-magnitude greater than on tape. It is very bad for the heads, especially the older ones which are made of soft metal. The extra track needs to be there even if not sounded. Had this problem back on Tommy. Louis