Old 35mm Sound Alignment Films - Query

[Mark Gulbrandsen]

Mark, I still have a Perspecta integrator from the Los Angeles theatre, I sold my other one to Dick Prather years ago, he restored it (re-capped and rebuilt freq traps) and I watched White Christmas in his screening room (with a density track!) it sounded great! I have a 20min VV promo reel, we played that and the sound worked great too! It was also IB Tech and had a density track!

I watched that at Dick's place too. It sounded great... Dick's father in law was an engineer at Tektronix. They took the filters out of the unit and over to Tektronix. They replaced the caps and then verified they were correct again.

[John Eickhof]

Also 400 hz was the most often used tone with wow and flutter meters

Mark, I was looking through my old Altec Service Notes about the test films, Gord is correct, 400 Hz was used for wow and flutter testing, and on the Academy Sound Test Reels of the day they used bass notes on the piano for an audible test for wow and flutter. I have 400Hz mono-optical test film as well as 4 track and full coat magnetic test film, in 35, and 16mm. Altec specs said to apply dummy load t o the amplifier or one channel at a time with the decabridge at standard fader level to check flutter.

[Steve Guttag]

SMPTE test films, both optical and magnetic for both 16mm and 35mm used 3150Hz for Flutter (which would work with Mark's meter using the "DIN" button).

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[Mark Gulbrandsen]

Hi John... Yes, I had some of that film a long long time ago. It did not specify any definite use on the film itself, just said 400 hz test film, it did not even say the level it was recorded at, but looking at the modulation on the film I imagined about 50%. However old Altec amplifier manuals spec running a 400 HZ film as a general level when balancing multiple amplifiers feeding different speakers in the same room. So, I seriously doubt it was used to measure Wow & flutter on projectors. I kinda doubt it was used for anything other than level. If Altec did use it, it would have been no where near a true W&F reading. You need a much higher frequency to properly resolve WOW & Flutter in a device. 400 HZ just isn't a high enough frequency to do that. Having personally measured wow and flutter on projectors using the SMPTE film, I can say it works great and the W &F Bridge indicates a very accurate reading based on the usual standards that were set up for measuring it. Also, Wow and flutter specs specify that frequencies are to be cut off of below 100 HZ.

When I was building copies of the R-8 sound reproducers to use in Dailies systems is where I really did a lot of measurements, they all came out within SMPTE Spec for W&F. I ended up making 8 pair more on top of the two pair that I already had. The other pair were sold to other Cinematographers and screening rooms. The picture shows Serial Film-Tech Cinema Systems Westrex R-8. Originally used for stereo and or multi-lingual playback on films that required it. This is one of the two pair of originals that I rented to shows and some times also operated. Normally the R-8 was mounted on three point pedestals with 2000' or 6000' magazines, and a top sprocket feed housing that acted like the lower sprocket in the projector.

Edit: Also, on the 400 hz note from a piano, you have many harmonics. So as far as that film went, you would have better luck with the 400 hz piano in hearing it audibly. I realize that field techs never carried real W&F bridges with them in the field, I never took mine, but that's still a pretty primitive way to be checking it.

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[John Eickhof]

Mark, yes you are correct, it's primitive but the films and info are dated from the early 30s, the 3k wow and flutter meters were introduced in the early 40s and newer from what I can tell and were designed for disc records and then magnetic tapes post war. The opt 400hz I have is 80% mod, the mag full track is at 1db reference and my 4track film is unmarked, just says 400Hz I had a w&f meter made by VARO that came with my Altec tools, its vacuum tube I would date from the early 50s. ..trust me, piano notes will point out slow wow very quickly to the ear!

[Mark Gulbrandsen]

Yes, now that's entirely possible based on the year it came out. Back then piano harmonics would have been a big aid, plus the U-base did not have a rotary stabilizer. So that was no doubt an important film to have on hand....

[Jim Cassedy]

Well, since we're discussing old sound test films, the other day I was going through my closet of
film-stuff, trying to find my Vitaphone Test disk, and I came across some of my old favorites:

The Elusive SR-D Channel ID
SRD_ID.jpg

And Its' Companion- -The SRD Sync Test
SRD_Test.jpg

I Always Liked This "Dual Purpose" Test Film. I had
bought a 1000ft Of It, Which Was Like Getting Enough
To Make 2000ft Of Test Loops.
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I Still Occasionally Need To Run 35 & 70mm Magnetic
Soundstuff, So I've Got Several Spools Of Mag Tests
MagSoundTests.jpg

I've also a 1000ft nitrate 35mm "Jiffy Test Reel" from the mid 1940's which has the
ubiquitous 'piano flutter test' section' as well as various test tones for testing sound
levels & optics, as well as clips from several movies of the day, with both VA & VD
tracks, to give a 'real world' test of dialogue. While the reel primarily was for testing
sound quality, it also had a focus chart, and a high-contrast line-and-grid chart you
could use to check or set shutter timing.

. . and no, I don't actually have a Vitaphone test disk, although I wish I did, if such a thing
ever existed. But I do have several Vitaphone disks, which I've previously posted pix of,
but there just doesn't seem to be a lot of demand for Vitaphone service techs lately.

.