Elmo ST-1200HD Sound Issue #1 - Adam

[Adam Deierling]

I have an Elmo ST-1200HD that puts off a horrible highpicted sound out of the balance track. Any ideas? Could it be the power amp? The machine has been in storage for many years and looks like its hardly ever been used.

[Tony Kelly]

hi adam i have a similar problem with mine except no sound at all, i was told by someone on ebay its the power amp and there is one or two for sale on ebay, i only assume yours is similar problem
ill find link to power amp, but you need some knowledge on soldering however the same guy told me he could do it for me for £65 all in i think.

[Steve Klare]

I've had this problem with my ST-1200HD from two different causes.

Number 1 is pretty easy: some audio switch or other had built up oxides and needed to be cleaned. I usually was able to work them a bunch of times and the squeal went away.

Number 2 is a lot harder. Some amplifier IC has gone bad and become unstable. Since it is only one channel, my guess is it's not the main power-amp IC but one of the pre-amp ICs that feeds it. This is what happened to mine. This IC is obsolete, but maybe 5 years ago I was able to buy several on E-bay so I could replace all four of them. (It's like a taillight bulb: when one goes, the others will soon follow...)

What was nasty about thus is I troubleshot it by guessing and had no idea if I was right until I did all the work! If I powered-up and it still squealed it would have been back to the old drawing-board after about two months!

I fellow collector was kind enough to send me the schematic for the sound board and I marked it up with the part numbers for the ICs before sending it to the Film-Tech warehouse:

ST-1200HD Sound Schematic

I really hope you wind up getting switch oxides instead of bad ICs: -a little repetitive switch work and/or maybe some contact cleaner is a lot less traumatic than replacing these ICs.

[Adam Deierling]

I tried your suggestion, cleaned the switches and pots. That seemed to clean things up tremendously! Thanks for the advice!

Now, any advice for getting richer sound out of this thing? My GS sounds very crisp but this st1200HD sounds muffled in comparison. Very heavy in the low ends. Perhaps thats just normal?

[Steve Klare]

That's great news, Adam! You don't want to go there if you can avoid it!

I often use my ST-1200HD for reels with music: they are capable of beautiful sound, but there can be...challenges.

ST-1200S are prone to running at low frame rates because of the friction wheel transmission on the shutter surface. When there is slippage in there the frame rates tend to fall off and this can effect the pitch of the audio. I've noticed with mine here and there (for example) female voices sound like they could use a decent shot of estrogen!

You could try running the same film on the ST and then the GS, stopwatch the times between the same two events on screen and compare the times to measure the difference in transport rates.

The motor speed is fairly well regulated because it follows the line frequency of the AC power. (-literally close enough you can set a clock by it!)

Where you lose FPS is in the stiffness of the rest of the transport mechanism. You often see a pronounced difference in speed as the mechanism runs a couple of minutes, as if the lube is softening up.

You could try changing the lube, especially where the worm is concerned:

My Great Worm-Glop Weekend!

I had something else on this same machine: the stiffness of the transport was enough when I first got it that the belt slipped on the motor pulley. It actually wore the sheave down and made the effective diameter smaller, and therefore slowed down the FPS even more! If you get a squeak the first couple of seconds after you shift into "Forward", this is happening to you.

[Adam Deierling]

The projectors running at the correct speed. I think its just the difference between the ST and GS models. Guess thats life...lol

Another issue I have is a noticeable hiss coming from the sound output. I notice it through the projector's speaker and when plugged into an external amp. Any thoughts on that one?

[Steve Lee]

Hi Adam,
Have you tried cleaning the soundhead, any build up of oxide on the magnetic heads will cause a significant dropout to the top end of the frequency, making audio sound muffled.
You will be surprised how much debris comes off of the soundtrack everytime it passes over the heads.
Just a thought.
Steve

[Steve Klare]

That is true, and while you are at it you can also de-magnetize the head very easily (-once you find a de-magnetizer, of course!)

-just please remember to do it with the machine unplugged. The demagnetizer puts out a low frequency alternating magnetic field and it'll make a pretty loud, rude noise if you are amplifying the voltage from the head!

Of course, this far down the road you can run into heads that are just plain worn-out. The Elmo heads seem to hold up long term, but nothing is forever.

[Rob Young]

Adam, in my time using both the GS and HD, the trusty Elmo ST1200HD has always given the best bass output via the moni outputs into an eq unit and then to an amp.

Spit mono or stereo, although stereo takes a lot of eq. to balance.

I mean floor shaking bass from my ST. Never got that same from a GS, ever.

Never managed that from the 4 GS projectors I have used, or any other super 8 projector.

Clarity? Well, yes the Beaulieu is best and "wow" free, and probably the most tolerant of the many magnetic stripes.

I gave up on the GS because of the maintenance issues, and I think it's a product of it's time.

Richest sound I've ever heard is from my ElmoST1200HD, if you accept some "wow"...which I don't.

Clearest and most stable sound, Beauliue 708El

[Adam Deierling]

The projector is basically new old stock. Bought from a guy who ran it a few times but basically stored in a closet. It was spotless. Regardless I still gave it a deep cleaning to be sure any dust or debris was removed. I also demagnetized the heads. I think its just the added warmth and low levels that i am not sued to.

What sort of EQ unit would you recommend?

[Rob Young]

I use an old 7 band "Realistic" from Tandy / Radio Shack on my Elmo, circa 1985!

I wanted to add a new eq unit to my Beaulieu a couple of years ago and it is actually quite difficult to find a modern day equivalent.

There are plenty on eBay, Technics were always good, but people do seem to want high prices for what are very old units.

The problem is that you need a stereo model to alter right and left tracks individually, although most modern units seem to control both tracks at the the same time.

I bought one of these;

Behringer | Product | FBQ800

They cost about £80.00 and although quite a flimsy build are very good indeed. I use it on my mono Beaulieu. A solution if you want to buy new would, I guess, be to buy two and use each one for each left / right channel, as although it has stereo input / output, as I said, it controls both together which is not what you want when trying to balance a super 8 stereo print (unless it is one of your own recordings with a much better tonal balance across both tracks).

The Behringer also has a handy db level boost which I find useful, especially if using with the moni outputs from the Elmo, which are below line level and thus very low output. I've never used the aux output, although others here I know do so maybe they can add more.

This Behringer also uses phono connections, which the older units tend to as well, whereas a lot of new eq units are designed for instruments and use balanced XLR connections.

Hope that's in some way helpful?

PS. Just had a quick look on eBay. This kind of thing would be good;

Rotel Graphic 10 Bands equaliser 1980 Models Great Sound. Full Working | eBay

[Adam Deierling]

Is it normal for these St1200HDs to have a hiss our of the speaker and line outs? Even at low volumes?

[Douglas Meltzer]

Since Adam is the OP of this thread, I have moved the posts concerning Robert Dreyer's ST-1200 to a new thread to avoid competing postings.

[Rob Young]

"Is it normal for these St1200HDs to have a hiss out of the speaker and line outs? Even at low volumes?"

I would say yes. And a degree of hum too.

I use the two rear moni outputs and completely kill the 16kHz range with the eq. All this does is remove hiss and has no audible effect on the soundtrack.

[Adam Deierling]

Thats a good idea, I will try that!