8mm Forum: Sound on Disc Without Sync Pulse

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Posted by Ernie Zahn (Member # 274) on December 25, 2013, 06:30 PM:

I was thinking of doing sound sync from a separate source for projecting.

I have an Elmo 1200HD. As I understand it, this doesnt have sync pulse. For those of you who sync sound without it, is it just a matter of timing it right?

Thanks!

Happy holidays!

Posted by Winbert Hutahaean (Member # 58) on December 25, 2013, 06:37 PM:

Speed does also matter.

Some films (LD, DVD) sometimes have speed faster/lower by milli-second. Also your ST-1200 projector, how can you be sure it is locked at 24 fps? due to the motor or belt it can be 23.94 fps or 24.12 fps. When you screen a long movie this gap will be widening and it will be out-of-synch after several minutes.

For those who are not so perfectionist like me probably can accept a milli-second out-of-synch. But for me, I cannot take it.

Although I have not tried, you can try to download a virtual DJ (google for it). This is a DJ software where you can slowdown or speed up the movie being played. The generic software is actually Audacity but this does not have easy play back features.

Moreover there are now plenty DJ consoles that can be hooked up to virtual DJ so you can have a physical control to the speed (e.g there is a slide for slowing down/speeding up the sound compared with using computer keyboard on Audiacity which is very hard to use)

Both are free softwares (home use only)

cheers,

[ December 25, 2013, 08:28 PM: Message edited by: Winbert Hutahaean ]

Posted by Dominique De Bast (Member # 3798) on December 25, 2013, 07:30 PM:

Winbert, I never tried it but there is an accessory that calculates the speed of a projector.

Posted by Winbert Hutahaean (Member # 58) on December 25, 2013, 08:05 PM:

Dominique, yes some projectors have speed control, either outside (GS series) or inside on the board. But you can not get the exact desired speed. We are talking a milli-second difference.

Posted by Pasquale DAlessio (Member # 2052) on December 25, 2013, 08:16 PM:

I've tried it and it doesn't work. The film was always out of sync.

Posted by Dominique De Bast (Member # 3798) on December 26, 2013, 12:53 AM:

Winbert, I was refering to an external accessory http://www.antanbazar.com/Pieces-neuves.php

Posted by Winbert Hutahaean (Member # 58) on December 26, 2013, 04:56 AM:

Dominique, then that device I think works just like a pedro box. If this is the case, it needs a projector with synch pulse. While Ernie's initial post says that he does not have one.

Posted by Dominique De Bast (Member # 3798) on December 26, 2013, 06:02 AM:

I don't know how it works. The ad doesn't say you need a specific projector to use this accessory so I thought you could use it with any projector.

Posted by Winbert Hutahaean (Member # 58) on December 26, 2013, 06:57 AM:

The generic name for this kind of device is "pulse generator". It feeds constant pulses to the projector (or any kind of devices, such as tape recorder, camera, reel to reel, etc) so the projector will be playing according to the number of pulses received. Therefore the devices need to have synch pulse capability.

We don't need actually pay that much of money to have this thing. Our home computer can also create that pulses and feed to any devices with synch pulse.

I read that in one thread here. Maybe someone can search for us.

Posted by Alexander Vandeputte (Member # 1803) on December 26, 2013, 10:17 AM:

The item sold by Antebazar is a speed meter. It is not a sync pulse devise and you cannot use it to sync up a projector with an external source. It is used to verify projector speed when adjusting the little pot meters on the internal motorboard of the projector. Even if you succeed in adjusting the machine to run at exactly 24fps, it will always drift off depending on issues like projector load, small variations in current etc...
So the device is best used for those who revise and service projectors.

Posted by Dominique De Bast (Member # 3798) on December 26, 2013, 01:55 PM:

This is also what I understood, Alexander.

Posted by Ernie Zahn (Member # 274) on January 07, 2014, 08:42 AM:

I tried to sync the sound of a film and it would be in sync for about 10-20 seconds then consistently fall out of sync. And would drift out of sync by a full second.

I suppose I can adjust the speed on VLC with a laptop.

Though I looked at the front of my projector and saw a port that says "sync" I didnt think the 1200HDs had sync pulse. Is this something else? I'm trying not to grt y hopes up.

Posted by Oemer Yalinkilic (Member # 86) on January 07, 2014, 09:25 AM:

If I remember right, the GS1200 give the sync signal and the ST1200 recive it.

Posted by Steve Klare (Member # 12) on January 07, 2014, 09:37 AM:

I think this is a 1/F switch: a switch closure per frame.

The manual says it's used to syncronize an Elmo tape recorder through an interface box.

Since the ST-1200 doesn't have a speed regulator for its motor, the cassette player would be changing it's speed to follow the projector.

Posted by Ernie Zahn (Member # 274) on January 07, 2014, 03:11 PM:

Hmm ok. Is it possible that the projector is playing back at a floating rate? Or is it set to sepcific speed even if it's not exactly 24fps?

Posted by Steve Klare (Member # 12) on January 07, 2014, 03:28 PM:

You might say the ST-1200 is designed to specific speeds by virtue of the AC motor, which follows the frequency of the AC voltage from the socket, and then you have the various speed ratios of the belts and pulleys and those two rollers that ride on the shutter wheel.

The DC motored machines have potentiometers on a control board: they are set to 18 or 24 FPS.

What this means is with everything as new, you get 18/24 FPS from the ST-1200. Then you throw in wear and old lube and other old-age symptoms and you get stiffness and slippage.

So you get something a little less than 24FPS, which isn't really consistent either.

Without an adjustment there's not a whole lot to be done about it anyway.

Posted by Andrew Woodcock (Member # 3260) on January 07, 2014, 05:13 PM:

with all AC driven machines I have always found there are far too many variations in the speed to allow for accurate re-recording in sync for any length of time. As mentioned earlier in this post, I also use a DJ software called PCDJVJ and tailor made Hardware controller called PCDJ DAC 3 with a AG Gigaport pro soundcard to achieve perfect synchronized recordings but only ever with an accurate electronically controlled DC machine such as my Bauer T610. Using the two combined it is very easy with only a minimal amount of practice to achieve perfect sync for 30mins or 600ft of film at a time. The Bauer also produces first class stereo recordings that far exceed the quality of the originals.

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