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 Post subject: Re: Elmo ST-800
PostPosted: Thu Oct 06, 2011 2:00 pm 
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You're lucky you can do some work yourself. I can almost change the lamp in mine.
:D
The Elfs are great workhorses. I've never had much trouble with either of mine though I've not used them much recently.

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 Post subject: Re: Elmo ST-800
PostPosted: Thu Oct 06, 2011 6:41 pm 
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Location: South Wales, UK
Yes Mike, my background was in electrical engineering, my friend is a dab hand at electronics and mechanics so between us we've done OK so far.
Two of the three ELFs we own between us have 2- bladed shutters so combined with the 250w lamps the light output is very good. We also found a 25mm lens for £40 a few years back.
Some time ago a little circuit diagram was posted on the 8mm Forum which made it possible to connect an external amplifier to the ELF via its speaker outlet - works a treat.
Sorry Dan, we seem to have hi-jacked the thread :oops:


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 Post subject: Re: Elmo ST-800
PostPosted: Thu Oct 06, 2011 6:53 pm 
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Sorry Dan, we seem to have hi-jacked the thread :oops:


Not at all! Thanks for the indepth info on the GS-800. A new review for the ELF sounds like it might be at hand.

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 Post subject: Re: Elmo ST-800
PostPosted: Sat Oct 15, 2011 1:26 pm 
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It was not the wear on the chute causing the popping noise, as you have called it. At the other 8mm forum this problem is called sound chatter. It is a well known fact that with Super 8 sound films this problem exists. It can never really be totally eliminated only lessened. The problem is that the sound track is advanced only 18 frames ahead of the picture, which is far too short a distance to really smooth out the pulsations from the pulldown claw, which creates this noise. On regular 8 sound film the sound is advanced 56 frames, which causes no problems at all because all pulsations from pulldown have died out long before reaching the sound heads. This is the biggest known problem with Super 8 magnetic sound projectors and most people never even notice it unless they isolate the projector from the speaker. As has been pointed out to me by experts there is no way of eliminating this problem without modifications to the projector. The projectors that do not show this fault are the expenisve machines that have a roller in front of the sound heads which smooths out the film....that is the only sure solution to the problem. The capstan and pinch rollers only purpose is to insure even speed just like on a tape recorder. Had the pinch roller and the capstan been placed before the sound heads things would have been much different but this is not the case due to the too short distance of only 18 frames! Some projectors exhibit this more than others but they all do it to some degree or other, especially when you pop on a pair of headphones! Some people have claimed that lubing the film and film path just before a show really helps this problem. Without modification there is no way to ever totally eliminate this problem because it always comes back to a more or less degree sooner or later. You may want to pop over to the other 8mm forum and do a search on "sound chatter" to fully understand the problem.


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 Post subject: Re: Elmo ST-800
PostPosted: Wed Oct 19, 2011 9:00 am 
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Oh, I know about the "chatter" discussion on the 8mm Forum: one of the major threads on the subject there is actually about this very machine! It just ends a while before the machine melted down and I rebuilt it. I "pop" over there quite often and recently passed 2,000 posts.

http://8mmforum.film-tech.com/cgi-bin/u ... 1;t=002888


At the time I was in the middle of doing those experiments I mentioned and I found the problem to be so pronounced I thought I could never have a remote speaker settup because the chatter would just be nastier sounding if isolated from the machine's noise. However, changing the guide lessened the problem below the point of even being noticeable when the speakers are very loud.

Maybe it's poor logic for me to imply the wear on the guide caused the chatter (...assuming I did). Problems often result from contributing factors: the speed of the ship, the place on the hull that hit the iceberg, the brittleness of the steel, the insufficient lifeboat space, the coldness of the water: change any one and the result could be vastly different. In this case I'm really saying that even though we are stuck with the 18 frame separation and the greater vibration at the end of that short lower loop, the wear on the guide greatly reduced the machine's ability to suppress the chatter.

It's probably also true to say I haven't solved the problem completely: odds are if you hung an oscilloscope on the audio signal you'd see little spikes at a roughly 24 Hz. rep rate, but oscilloscopes don't listen to movies, human ears do, and my human ears aren't hearing chatter anymore!


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