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Posted by Sam Hunter (Member # 1119) on 09-16-2002, 11:19 PM:
What do you use to align the optics in a soundhead?
Is it an RP40 test film?
Who has one if it is?
Thanks!------------------
Samual Hunter Sr.
KC5ZSL
Posted by Manny Knowles (Member # 1171) on 09-16-2002, 11:22 PM:
This is commonly referred to as an "A-Chain Alignment."Minimum test film requirements for analog:
Dolby Tone (Cat 69T)
Dolby Pink Noise (Cat 69P)
Crosstalk*
Buzz Track
There are others, too, but these are the ones that ALWAYS get mentioned in manuals and they are the only ones I use.
You will also need an oscilloscope and a real-time analyzer (RTA). At first glance, the procedure may seem like one great big mystery: lots of test films and gadgets. But -- like a lot of things -- it's not a terribly complicated if you understand what's going on.
A friendly tip: Let a professional do it, or learn from a pro. I don't think it's the sort of thing where you want to be reading instructions "as you go."
Just curious: What kind of sound head and processor?
~Manny.
*Footnote: I'm told that with my LED reverse-scan units, I don't need to use the crosstalk anymore. I still use it "for old time's sake" but when it runs out (I have about 100 feet) I probably won't re-order.
Posted by Sam Hunter (Member # 1119) on 09-16-2002, 11:29 PM:
A chain, got it.
For right now I will be using mono, stereo later, and anything else, quite a while.
I will need a Buzz track alignment and 7Khz tone for focusing adjustments.
RCA 9030, with Kelmar Mono pickup and standard lamps.------------------
Samual Hunter Sr.
KC5ZSL
Posted by Manny Knowles (Member # 1171) on 09-16-2002, 11:32 PM:
I think you still need to use Pink Noise film (and the RTA) to get the focus correct.
Posted by Rick Long (Member # 213) on 09-16-2002, 11:41 PM:
RTA's for mono focus? We didn't need no steenking RTA's!7KHz or even better, 9Khz is great for getting focus on mono systems. It takes a little practice, (9KHz threaded and running) twisting the lens as well as moving it back and forth to get the best focus and azimuth, as read with an a.c. meter at the output of the amplifier (most-sensitive scale). Highest output means good focus and azimuth. A warning tho, this is a "high Q" adjustment. At one point you will see the meter suddenly go high and back to low again. You should never be happy until you are sure you have the highest output level possible. This also ranks #4 on the list of reasons sound men drink.
Another method: Without the projector running, and a buisness card nestled in the sound drum where your temporarily removed solar cell used to be, thread 9KHz film. Exciter on, look at the image. Now move the film with your finger slightly. You should see several "cyles" of track on the image on the card, moving as you touch the film. Now adjust the lens until the lens is so well focussed that you no longer see movement, but simply black/white flashes. This means you are in focus.
Posted by Sam Hunter (Member # 1119) on 09-16-2002, 11:53 PM:
I was referencing to the soundhead manual that calls for a buzz track (lateral alignment) and a 7-9Khz test loop for optical alignment.
So now I need to find them.
Any ideas? I found out that RP40 is for the picture head alignment, focusing and such things.
------------------
Samual Hunter Sr.
KC5ZSL
Posted by Rick Long (Member # 213) on 09-17-2002, 12:06 AM:
Your local theatre supply organization should be able to supply these test films. You will not need much, although I suggest about a 10 to 12 foot loop, capable of running through the projector as well as the soundhead, approximating actual running conditions. Remember emulsion side goes towards the lamphouse.
Posted by John Anastasio (Member # 607) on 09-17-2002, 06:12 AM:
You may see the meter peak at several different azimuth settings. There are "secondary" peaks on either side of the proper azimuth. Go for the absolutely highest one. It's very much the same procedure used to align magnetic tape head azimuth. If you've got a scope, focus for the highest output and sharpest waveform. You'll hear the difference as well. The buzz will take on a really "edgy" quality to it.
Posted by John Anastasio (Member # 607) on 09-17-2002, 06:13 AM:
Oops..didnt' mean to use the word "buzz" there. The buzz track is for lateral alignment....but when it's focused properly, it really "buzzes".
Posted by John Pytlak (Member # 331) on 09-17-2002, 07:35 AM:
Unfortunately, the Buzz Track is the only 35mm optical sound test film that SMPTE still carries. The SMPTE has been unable to find a lab willing to resurrect the old equipment used to make the other films at a reasonable price, so they are all "out of stock": 
http://smpte.org/smpte_store/test_materials/ ------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion
Posted by Steve Guttag (Member # 268) on 09-17-2002, 07:35 AM:
As for mono, yup, 7 and 9KHz are the focus tools. Go back and forth between focus and lateral position (buzz track)...you can't finalize the lateral position until your focus is perfect (that will have the slit at its widest).For reverse scan, I agree on the dumping of crosstalk (cat. 97) but it should be replaced with Cat. 566 (illumination film) to ensure the film is aligned to the LED.
Steve
------------------
"Old projectionists never die, they just changeover!"
Posted by Don Sneed (Member # 955) on 09-17-2002, 08:16 AM:
7K & 9K test film, I have been told that is no longer made, or I can't get any....so I use pink noise & a RTA to align the optics for mono, for stereo all test film Manny listed...I still have many mono theatres but no one have 7 & 9K test film anymore, Pink noise (69P) & a RTA works fine....