Movie Theatre - Sound System Advice

[spkrman57]

It looks like it would not be far out of my way when traveling to Toledo to visit friends.

Regards, Ron

[Oldmics]

Joe

May I ask the intended application of this vintage system?

I see where you mention that you are not going into the first run movie business and that a modern style system would not be required.You however mention the desire to get "the stage up and running"

I see the picture of the facility with marquee advertising for a band on one side and a DJ on the other side.

Will this system be required to do a multi duty situation such as any live sound reinforcement demands or a D.J.?

The requirements for such a multi use live system verses a strictly theater sound track movie reproduction system is considerably different.

Consider all of your requirements so that we can guide you along in the best fashion.

Thanks,Oldmics

[Lee in Montreal]

Seen in another theater in Wisconsin where activities mixed stage shows and movies. Another great combo of old and new technology. Altec A2 bass cabs and JBL 2360 horns.

http://img96.imageshack.us/img96/9780/img5253i.jpg

[Norwalk Theatre]

Ron - You are certainly welcome. You can't miss the place!

Lee - Appreciate the info.

Oldmics - Fair question! Our plan is to get the facility open using the stage for music, theatrical performances, and speakers. It has a huge stage! None of these should require the use of the theatre's sound system that we are discussing. The sound system is hooked to the projectors (which would only be used if we had someone who had a special desire to see a movie on the carbon-arc units), and it also has an "aux in" for just general music in the theatre space.

The theatre has large speaker boxes (added in the last 20 years or so, now empty) into which modern speakers could be added at any time for actual cinema use. This is in the plan for the future once the building's immediate needs are met (roof!)

My original question was in regards to wiring these units. Based on the (very helpful) feedback so far, it's clear that the 250 ohm RCA crossovers are now no longer useful with the Carver amp (and also due to age). If I secure 8 ohm crossovers set to 800 hz or lower, I'm still unclear as to the wiring from them through the autoformers to the 30 ohm woofers and ?? ohm horn drivers. I've yet to find a clear diagram to either wire them again or confirm if the current wiring is correct.

In summary - just want to get the units wired cleanly (you should see the rat's nest) with no upgrades currently to get things functional while bigger renovation projects get the lion's share. Any advice is appreciated, and forgive me if I'm using kindergarten terms here (because that's the level I'm at!)

Joe

[Mr. Widget]

My original question was in regards to wiring these units. Based on the (very helpful) feedback so far, it's clear that the 250 ohm RCA crossovers are now no longer useful with the Carver amp (and also due to age). If I secure 8 ohm crossovers set to 800 hz or lower, I'm still unclear as to the wiring from them through the autoformers to the 30 ohm woofers and ?? ohm horn drivers. I've yet to find a clear diagram to either wire them again or confirm if the current wiring is correct.

...and forgive me if I'm using kindergarten terms here (because that's the level I'm at!)

It doesn't quite work that way.

Since these are desirable vintage speakers and it would be a shame to damage them, I think you need to get some real help as opposed to the virtual type you can get here. You really need someone who knows about this specialized gear to check it out and make sure that everything is wired properly before you fire up the system.


Widget

[1audiohack]

I've been thinking about this all day and concur with Mr Widget.

I too suggest you secure the services of one who really knows systems like these, a professional sound system person, not just someone who is enthusiastic to tinker with it. Compression drivers are fragile when it comes to what's electrically fed to them and repair parts are likely very scarce if obtainable at all at any price. Also, some of the components there have very real value. Don't let anyone "help you out" by helping you dispose of all that "old stuff."

Consider it similar to a very valuable old car that hasn't run in many years, there are many things that should be checked out before you connect a charged battery to it much less engage the starter motor.

I've been trying to justify a trip out to check it out but I want no part of Ohio winter. :^)

[Norwalk Theatre]

Fair enough, gents. I'll scratch this portion of the rehab for now and concentrate on other items.

If anyone cares to visit, you're welcome to stop by! For some reason, it doesn't seem that we have "Ohio winters" anymore. She may choose to prove me wrong this year, though.

One last item - short of lurking here (not enough time), is there a reference you'd suggest that would allow me to start reading and learning the items I'm missing? I've got enough years of engineering under my belt to know that i'm a fast study given good material.

Thanks again, guys.

Joe

[grumpy]

Consider it similar to a very valuable old car that hasn't run in many years, there are many things that should be checked out before you connect a charged battery to it much less engage the starter motor.

Exact analogy I was thinking of... Might even be worth having some of the pieces inventoried for valuation and the economics of restoration vs replacement.

[Earl K]

Joe,


I don't know of any light reading ( on this subject ) / only the heavy stuff such as this ;

or this


Since you've decided to leave "well enough alone" for now, here's some info to ponder ( for posterity ) these ( following images ) belong to Stephane Rame .

[Fort Knox]

That "reverb box" was probobly the origonal balcony speaker
(15' over main stage)

[CONVERGENCE]

A good web site is Film Tech Forum . Ask them your question and you will get the best answer there . There'S part A and B to cinema installations. THEY WILL ASK YOU QUESTIONS ABOUT YOUR PROJECTORS AND YOUR DOLBY PROCESSOR. tHE NEW PROCESSOR COMES WITH ACTIVE CROSS OVER. ANOHER POINT IS FILM DISTRIBUTION THAT WILL END IN 2013. EVRY CINEMA MUST CONVERT TO DIGITAL PROJECTORS.

http://www.film-tech.com/ubb/gatekeeper.html

[rlsound]

Hi Joe,

I'm not familiar with the RCA's first hand but have worked in cinema for years.

100' run usually dictates 12 gauge wire or less ( 10 gauge for subs ) but I would be more inclined to install the amps closer to the speakers and run a balanced connection ( if your processor supports it ) to the amps backstage. I would think about the future if you do choose to run new wire from the booth to the speakers and go with 12 gauge. The requirements at the moment may not require it, but once you start upgrading and upping the watts, you will need the thicker cable. Belden is commonly used in cinema applications.

Like you said, I would hold off on dialing this system in until you have the funds to do it correctly. It might be a good system at the moment for intermission music, but wouldn't put much faith in it holding up to the demands of digital soundtracks. Chances are, you will destroy a rare and vintage piece of gear.

Specific questions for the experts:
1) The RCA units have the original MI-9597A Crossovers and two each of the MI-9472A Autoformers (all good condition). I would very much like some advice relative to an overall wiring diagram and specfically how to best connect to the amplifier. What taps on the autoformers are used? Any other tips to connect these units?
2) Any advice as to wire size/quality for the near 100' runs from the amp to the speakers?
3) Anything else that come to mind?