Elmo GS1200 wow

[Paul Adsett]

In my experience, Elmo machines are susceptible to WOW. It seems to be associated with the small diameter of the brass sound capstan and variations in the wind-up tension on the rear spool. Both my GS 1200'S will exhibit wow on certain sections of certain films, other films being seemingly wow free. This is one reason I like Eumigs. I have never heard wow on any Eumig projector, be it series 800 or series 900. If you look at the Eumigs, the sound capstan diameter is much bigger than the Elmo's and the rubber roller is much larger and is really sprung down hard, very effectively clamping the film and preventing slippage. I think the Elmo's are really susceptible to variations in the coefficient of friction of the film, which of course is really influenced by film lubrication products.
But IMO the equally important root cause of WOW on the Elmo is tugging or tension variation by the take up spool. If you are running film on the Elmo and you hear wow, just put your hand on the take up reel and stop it for a few seconds and you will find that the wow is totally gone. Also look at the black spring loaded tensioning piece right below the sound capstan. If you see this moving up and down then you have wow, it should be rock steady or at least moving up and down very slowly. Yesterday I was running a film on my version 1 GS1200 and the wow was very bad, with the black tensioner moving up and down like crazy. So I removed the take up motor and cleaned and lubricated all the little gears and also a drop of oil into the shaft of the ratchet. I also cleaned and lubricated all the pulleys and the cogged belt in the take up arm. Result - no wow and the tensioner is now rock steady.
If you have a bad motor, or one with heavily worn brushes, this can of course induce significant torque variations into the take up reel. The solution is then to either replace the motor, or take it apart and clean it and maybe install new brushes. This is a tricky operation though, as the brushes are easily broken, as I found out a couple of weeks ago when I was doing this.
One other thing that helps reduce wow is to use the large 1200ft Elmo reel. The higher rotary inertia of this metal reel smooth's out tension variation (acting like a flywheel), so it is good practice to use this as your take up reel all the time, even when projecting short 200 ft films.

[Graham Ritchie]

Interesting point about the take up reel Paul, I use the Elmo 1200ft for everything, regarding the motor brushes, I used a couple of cotton buds, the plastic type with the ends cut, to carefully compress the brushes against the springs until the motor cover in on enough so when I release the brushes they spring down onto the commutator itself. It is tricky to do and a lot of care required.

[Lee Mannering]

Back in el day when I projected at the amateur film festivals many of the films contained cement splices from the old hands. The Elmo's would wow away happily at every single join at 18fps with the more experienced film makers looking back at you in the audience then after the show saying 'my film didn't do that at home' Grrr. Other keen film makers using the GS used to often chat over the sound issue and I eventually started filming at 24fps which helped the sound a little, plus switching away from CIR joins using the near invisible Wurker 2 frame splices. From a film makers point on view far from ideal and I favored the Norisound 320 in the 80's with a good Schneider lens in for shows out and about back then with its rear sprung gate etc and certainly a film makers projector.

Will have a go and the lube up Paul as one of my Elmo machines really does not like Poly film although it has bee a REEL work horse over the years since 1983. Going to replace the recording cap for can do that at the same time and will report back.