The AM Forum

I found this link for closed drive in movie places. Maybe there's one near you. You should go over and see if there is any old amplifiers hanging around. Some are worth big bucks. Others too far gone may be worth parts. Watch out for snakes & owners ;D ;D

http://www.pinballrebel.com/drive/ghost/ghost.htm (http://www.pinballrebel.com/drive/ghost/ghost.htm)

Thanks for the post Terry,
Having worked in the drive-in movie business for a few years its fun to see these old theaters.

Bill

I kinda figgered BILL would be in here for movie theaters and the big Arc Lamp projection equipment.........hi Bill.........We never met or talked about the past with those big machines.

Any way, we have a drive-in theater close to our town in Western Pa. and they use an FM transmitting system for the sound.

Better than the battered speakers that used to hang on the windows. Drive off and yank them out of the pole.
They probably had banks of 100 watt amps and the familiar 70volt distribution system.


Fred

Nice web site. Some of those drive-ins were huge operations. What do you think Bill....5kw of light to get the screen?? Or larger??
Did you use a product called Bonami(?) to clean the mirror in the lamp house?
Arc Lamps .....yea......DC AMPS........Huge rectumfinders

Fred, here is my restored 35mm machine in the hamshack.  It has stereo photo sound pick up (no Dolby or digital --- too many bucks). I can project standard spherical lens (flat) or Cinemascope onto a 4 X 8 foot screen.  No carbon arc, though, don't much like the ventilation required and fooling around with carbon rods, etc.  I have a 450 W xenon projection lamp that does the job (not in photo below).

I had a friend who worked in one back in the 60's.  The audio amplifier used a pair of 805's and the output transformer was about the size of 300 watt modulation transformer.

I don't know why they didn't run Part 15 transmitters on the broadcast band (AM back when drive-ins were in vogue).  The audio quality would have been much better and the cost a lot lower than those dinky little speakers on a pole for every car.  They usually sounded so awful that slopbucket audio would have been a big improvement.  Maybe they were concerned that a lot of cars didn't have radios back then.  But how many people paid any attention to the show when they went to the drive-in?

I remember the Arapaho Theater in Richardson TX. I was 14 when it was torn down and I was given the 15KV 60mA neon sign transformer.

The Circle Drive In in Waco, the image of the Bear (Baylor!) looked much better in the day.

All that I know of around here +100 miles, basically everything was stripped long before I was able to investigate.

The advent of solid state car radios, I think, made made drive-in sound over low power transmitters practical.

Bingo!

I wonder how long a 6 volt car battery could keep a vibrator-equipped hollow-state car radio operating...A 2-hour movie might be pushing it.

Plus there was the problem of gassing the people behind you when you'd leave the engine running on that full size Belchfire 8.

Even in 1970 a car radio was optional, and to many, a frivilous and dangerous driving distraction.

What does this mean?

Fred,
I was always fascinated with the whole process of presenting a motion picture. The equipment that is used to arrive at the finished product (movie the public sees on the screen) is quite complicated. The movie "projector" is actually 3 separate pieces of equipment as u know. They are:
The lamp house that provides the light...
The machine head or the actual part that handles the film and includes the lense...
And the sound head that picks up the sound from the film and also drives the rest the projector.....
The lamp house that was used in the old days used carbon rods to generate the light.....it was powered from various sources depending on the technology of the time. It started in the early days using motor generators.....then went to transformer power supply's using tungor rectifier toobs (the power supply has to by DC) and finally solid state power supply's. These carbon lamps needed something between about 50 amps and 500 amps or more at about 32 volts depending on the size of the screen. The lamps had to have drive mechanisms that would feed the carbons together and maintain the correct gap as the carbons were used. The positive carbon burned faster than the negative and the drive had to maintain the proper ratio.
Any way.....more to come on how these fantastic machines work if anyone is interested!


Bill     

I had forgot about that.  I remember when I was a kid and we got our first car that had a radio, my father would scold me for listening to the radio for more than a couple of minutes while the car was parked and the engine not running.  The first 6-volt tubes in the 30's were designed for automotive use, and their "low-drain" filaments were touted in the ads by RCA and other manufacturers.  Most a.c. sets back then used 2.5 volt filament tubes.  Those things have a long enough warm-up period that it takes the radio about as much time to start playing after you turn on the switch as it does for a computer to boot up from a cold start.

When I was in the army we had a lot of mobile radios that used 1.5 volt tubes and 2.5 volt tubes. When someone would forget to turn off the radios before starting the jeep, the kickback from the starter took out about 1/2 dozen tubes. Did that happen in those old car radios? Most of the old car radios that I've seen use 6SK7-6V6-6H6 and the like. The vibrators would go bad quite often. The rectifiers in them were a full metal jacket type. you could pull the cover off and then you would see a tripey blue glow come from the rectifier.  I don't think they were MV's.

Don,
They first came out with radio sound for drive-ins in about 1975 or so. I think the system was from Radio System. It was a solid state transmitter crystal controlled and had a built in antenna matching network that would try and match the transmitter to the existing underground wiring used for the speakers. I had one of the first ones made that I used for my drive-in in Champlain NY.
We still had some speakers for people that either did not have radios in there car or they did not want to use their radio fearing the radio would run down the battery.
Bill

Terry,
Looks like we posted our reply's the same time!
One more thing.......the first radio systems were AM........then they came out with stereo FM transmitters. If the drive-in wanted to spend the money for stereo sound heads and dolby stereo decoders then they would have stereo in the cars if so equipped. 

Bill

This reminds me...during the Apollo 11 Moon Mission, I was projecting Romeo and Juliet at the local drive in. It was a fun but short-lived experience, as I was filling in for the vacationing regular projectionist. Some of the clientele were quite rowdy. The projection building also housed the restrooms, where the urinals and toilets would mysteriously become plugged up and overflow. One night I smelled smoke...went out into the lobby to find a movie poster burning off the wall. I remember splicing in the trailers, concession, and "3 minutes 'til showtime" ads; unpacking, loading, and rewinding the reels; turning on the power supplies and striking the carbon arcs and having to be mindful of having sufficient carbon length to finish a reel; and using either a standard or CinemaScope lens. One of the projectors had a mechanical quirk of occasionally stalling and melting a frame of the film...which would promptly initiate a cacophony of honking horns. I once had a problem with people siting on a wooden rail in front of the building and putting their hands into the projector light to cast shadows onto the screen. There was an oil can in the projection room which I used to oil the rail...problem solved. ;D

This drive in movie site has been replaced by parking lots, a grocery store, a variety store, a hardware store, restaurants and an eye clinic.  :'(

Terry

The nearest drive-in movie place here used to show X-rated flicks. New owners came in and added 2 more additional screens and did weekend carload deals. The place has been very successful.

I can hear it now --

Q: So what's showing ?

A:  EVERYTHING  !!

I remember that well. Speaking of guys being rowdy, some of the young bucks would end up in a fight usually over a girlfriend spotted with someone else in another car ;D ;D


I think we should keep comments about the X part on the down low. No point having a fine old nostalgia era posts being pulled.

I think those were the best good old days never to be seen again in this country.
Yes, drive in movies had to make way for cable TV. I'd rather have 2000 drives in theaters to one cable channel if it would bring back what was to me. the good old days

This one in the Baltimore area is still alive and well. It's like stepping back in time. It was fun going to it when we lived in that area.


http://www.bengies.com/

Terry said:

LOL  ;D  ;D  ;D

Speaking of Danville area drive ins. There was a guy by the name of David Bell who lived in Danville who was a part owner of that one. He was also a ham an somewhat a mentor to me. Did you ever hear of him Mike? He must be an Sk for decades by now.

there's one drive in still working in Milford NH too!  We've been and taken the kids.  Quite an experience... (why do we have to wait for the move to start Dad???  Just go play on the swings until it does!)

yea it looks like movie theaters have given way to the zenon lamp and are fully automated. The entire movie is on a huge turntable and it's only one projector per theater for the multi-cinema places.
We gots to go to Pittsburgh and look at an IMAX movie in 3D. And listen to about 1000 watts of audio.

I always liked to tweek the optical sound head alignment in the "old days" for the clearest sound possible. The exciter bulb was lit by an RF type voltage (I never replaced one of those) to eliminate hum.I think optical sound was good to about 7500 hz??????

Fred

Some of those theaters boast 10000-15000 watts.

Terry said:
Yep, the old Point Drive In. Does pretty brisk business in the summer. I never heard of him but I'll check one of those call-sign data bases for the area.

quote]When I was in the army we had a lot of mobile radios that used 1.5 volt tubes and 2.5 volt tubes. When someone would forget to turn off the radios before starting the jeep, the kickback from the starter took out about 1/2 dozen tubes. Did that happen in those old car radios? [/quote]

Fortunately, the car radios were off line during the start cycle in most cars.  Apparently  the 6 V octal tubes were also a little heartier than those used in the "mil specs" radios of the day.  I've had that happen to me, too, with the military radios.  It still happened at least up thru the RT-524 [VRC-12 series] but there it took out the power supply module and, if you were really unlucky, the 6 sedly 4th ethelon maintenance].power transistors that are mounted on the chassis directly [which was supposedly 4th echelon maintenance].  The "protection circuits" designed to prevent this never were installed for some reason.  Of course they were not part of the installation kit, either.

Ever since the wholesale transition from carbon arc lighting for film projection, to high pressure xenon projection lamps, the public has been largely deprived of the brilliant saturated color many of the film directors and their studios shot during the course of making a film.

This is due to the very high replacement cost of these xenon lamps, and their fairly short operating lifetime. The movie theater chains, in an effort to reduce the maintenance costs of the projection equipment, actually reduce the voltage applied to the lamp by typically about 25%, thereby extending it's operating lifetime. At the same time, the image reproduction quality suffers due to the reduction in luminosity.

I recall a group created several years ago by a number of well-known film directors to try to force the big corporate theatre chains (National Amusements, et al) to run the normal (unreduced) luminosity of the projection lamp, so as to show the film the way the director wanted; i.e., the correct and dramatic rendition and portrayal of the color. I don't think this went too far, as the theatre chains did not quite see it the same way as the directors did. My experience is that some of the smaller, non-corporate theatre chains that value art over profit are willing to project films in their houses at full luminosity. There is a local (and quite small) theatre in Huntington, NY that Janet and I frequent regularly to see films projected in full brilliance and with absolutely superb sound reproduction.

I don't believe any of the studios are shooting film with optical or magnetic soundtracks anymore; I think all films intended for mainstream theatre projection now have the soundtrack on a separate CD that is provided with the film itself. The CD is electronically synchronized with the film. The original talkie format released in 1927 (Al Jolson's "The Jazz Singer"), known as the Western Electric/Warner Brothers Vitaphone System, employed a 30" diameter phonograph record  mechanically coupled to and driven from the film projector so as to maintain correct sound synchronization. Optical sound-on-film recording and reproduction technology was developed by both RCA (their Photophone Sound System) and Western Electric (the Mirrophonic Sound System) in the very early 1930s, and that spelled the demise of the Vitaphone system, although a number of low-budget movie studios and theatres contrinued using the Vitaphone format through the early 1940s. It was cinema sound that was the public's first real introduction to high-fidelity sound reproduction in the early 1930s.

Talkies in the 1920s and early 1930s were the epitome of high technology, and some of the most talented and famous engineers associated with the development of modern audio recording and reproduction, such as Dr. Harry Olson of RCA, were closely involved with their development.

It was highly prescient that the "Jazz Singer" closed with Jolson uttering the famous words, "you ain't seen nothin' yet!".

Perhaps one of the greatest all-time misjudgements of the public by a businessman was made in 1926, when Louis B. Mayer of Metro-Goldwyn Mayer stated his opinion as to the future of talking films vs. the then popular silent films, when he said, "nobody wants to hear actors talk!"

73,

Bruce

Bruce I had no idea that these new-age crap theaters were reducing voltage on the bulb to extend life and we have to look at degraded pictures.

Bill KC2IFR and some others here have had the experience to present to the public a movie in all of its glory and brilliance. I'm glad that there is a movie theater around that permits you to see what the director invisioned.

What I see in these multi-suck theaters is a really terrible visual experience. Dark pics and out of focus. Loud multi-channel sound WOW......that's it!!!
We're still going for the IMAX 3D. That might be the only way to see the ultimate of everything!!!!

I see better pics at home on the Blue-Ray and HDMI plug on my Sony proj TV 57"

Fred

Bruce,
Nice post.......most accurate. Not sure about running xenon lamps at reduced voltage. I had a LOT of experience with the early xenons and found that reducing the arc voltage (thus reducing the current) would cause an unstable arc and if it didn't extinguish, it would wonder around the face of the anode causing the "sweet spot" on the screen to wonder also. No matter what folks think about the life of a xenon lamp.........its still a LOT cheaper that using consumable electrodes.........ie: carbon rods. If the xenon lamp is installed properly, cooled properly (very important), and operated at the correct voltage, it will last many hours. And as for cooling........the lamp exhaust fan should be left on for a while AFTER the arc is extinguished and the power is shut off.
Where most early failures occur is in the seal between the electrodes and the quartz envelope. If u have ever heard one if these burst, u know what Im talking about!

Bill
 

Hi Bill,

I had no idea that you were involved as a theatre projectionist!

I have always been fascinated by the whole cinema process, from the shooting of the film and recording of the sound, to the playback in the theatre. Most folks have literally no idea as to the complexity of this process, particularly in the days of optical sound-on-film recording and reproduction. A wonderful reference as to this entire process is the "Audio Cyclopedia" by Howard Tremaine. BTW, in my opinion, any real enthusiast and student of audio should have this book.

In my case, this interest goes back to 8th grade, when a classmate of mine informed me that his dad was a projectionist at the local movie palace in Northport, NY, where I grew up. He and his father invited me down to the theatre one night, and I vividly recall the graciousness his father displayed, showing me in detail the Simplex projectors, the brilliance of the carbon arc in the lamphouse, when to start the other projector running on cue, as the previous reel of film was completed; you get the picture. Later, he took me backstage, where I saw for the first time the enormous Altec-Lansing Voice of the Theatre loudspeakers behind the screen. There were three of them; left, center, and right. These were not the smaller A-7 Voice of the Theatres (of which I have a pair) that most of us are familiar with, but the huge A-4 system that stood probably 12 feet in height and 10 feet in width, including the multicellular horns and compression drivers for high frequency projection and dispersion control.

So how does the sound (especially the high frequencies) from the loudspeakers pass through the theatre screen relatively unattenuated? The screen is actually a porous material, and this porosity also provides the benefit of the screen not moving due to air currents from the air conditioning or heating system, etc.

My friend's dad also told me that the projectionist's union was one of the most difficult unions to enter, at least at that time, which was around 1967. It was pretty much a father-to-son job as I recall.

This being the case, my friend (who I still keep in touch with to this day) did enter the projectionists union after he graduated from college, and ran films on a part-time basis to supplement his income for years. I used to visit him in the local multiplex, where he would be solely responsible for running the projection equipment in 10 theatres within the multiplex simultaneously! With the modern equipment, such as the Castle table, etc., this now became possible.

A few years ago, he quit the business. His son had zero interest in entering the projectionist field and became an electrical engineer instead. Probably a smart move.

73,

Bruce

Bruce,
I started out as a projectionist in a bar at Killington Vt. Long story! I wound up as the head projectionist for a chain of theaters in Rutland Vt. and I had a small business repairing projection and sound equipment in mom and pop theaters in upstate NY and new England. I worked on mostly old equipment, from Western Electric sound equipment (yup......the old stuff) to Simplex, Century, and Ballantyne projectors. More on that stuff later.
BTW.......check out this site.........this is the future. There is one cinema in Albany using this system.
http://www.bigscreen.com/about/help.php?id=36 (http://www.bigscreen.com/about/help.php?id=36)

Bill

More stuff!
Someone on this thread mentioned the power supply for the exciter lamp that supplies  the light for the sound heads. The only supplies I have ever seen were ether DC or AC. The AC supplies were used for drive ins because the car speakers had no bass response therefor the AC hum was not a problem. Indoor theaters used a very stiff DC voltage to power the exciter lamp. Before the advent of optical stereo, the frequency response of the average theater sound system only went out to maybe 8KC if u were lucky. I used a 7KC loop to adjust the focus of the exciter lamp on the film soundtrack.
When they came out with "Cinema Scope".......they also introduced stereo that used magnetic tracks on either side of the 35 MM film. This required the installation of mag sound heads that were mounted just below the feed reel  on the top of the projector in a unit called the "pent house".
As for the many different amplifiers used in theaters and drive ins.........there were many and most were built like tanks. Power levels were from about 15 watts for the old Western Electric amps to 500 watts or more for large drive ins.
The drive ins used a 70 volt distribution system  for the car speakers.

Bill       

I understand the motion picture releases these days are color timed (balanced) for xenon illumination.  Yeh, carbon was neat stuff, but xenon enabled less attention to the projection process saving exhibitors lots of bucks.  With xenon, films could be "plattered" alowing them to be run on a single machine eliminating change-overs. Thus the popcorn-jocks could run the films and quality projection went into the toilet.

Oh well.  Anyway, I have a 450 W Christie xenon lamp on my home 35mm system and it's not at all that bad.   Carbon, in a home environment, would require ventilation to the great outdoors.  A small xenon doesn't produce much ozone, and is safe to exhaust indoors...and helps warm things up on cold winter nights while the xyl abd I are enjoying flicks on the big screen.

One left over here, The Sunset Drive-in on US19 north.
Grafton D.I. just shut down a couple of years ago.   So the county had 5 , now 1.

In other news,

Jeeze, my OM used to complain about heaters in cars being a luxury.   The paint was worn out on the drivers side too where he laid his arm in the summer with the window down all the time.   Everybody in the sales biz was deaf in the left ear.  Remember those wire back seat thingies that you used to sit on for air circulation in the summer?   

Cup holders? h... you were lucky to have an ash tray.  Coffee, cig, standing up kid (or girl), steering wheel, shift knob, sales hand-outs and pen all quite handy for your typical jaded, cool and dextrous driver.

Jeff,
No doubt carbon is a thing of the past. Xenon is far superior to carbon for all the reasons u listed and more.
35 MM at your house??
What do u use for the projector(s) and where do u get the prints?

Bill

Bill, yes have 35mm at home.  I use a Brenkert BX-40 on a Simplex SH-1000 soundhead with stereo solar cell pick up.  Trailers are easy to find, features somewhat of a different story.  Here's a couple of sites for you:

http://www.35mmforum.com/

http://www.film-tech.com/

OK Jeff,
That Brenkert BX-40 is a fine machine. Brenkert equipment was expensive for its time and was built like a tank. I think Brenkert went under because of its price.....not its quality.
Thanks for the links.....Ill check 'em out.

Bill

I was trying to "quote" Bill on the exciter lamps but it's a long post and the usual jumping up and down happens. I guess for AMFONE I'll have to run FireFox.

I thought I interpreted what I saw in a Bell & Howell 16mm projector as an oscillator circuit to drive the bulb. It would be a much easier task to lite the bulb with a high freq A.C. signal than trying to lite up with a pure D.C. voltage. The built-in amp in that projector would roar when the protective cover was removed from the exciter lamp housing. That was during my military days in sunny South Viet Nam. I ran the projector in the "club" and picked up the movies from some military depot in town. We even had a cinema-scope lens for that puppy. We would put up extra sheets for those movies.....WOW!!
But you are on track Bill. I did a search and found the requirements for a Century sound head and they lit the bulb with 9Volts @ 4A.

Fred

Very interesting thread!  I've been  a 16mm collector for years, and have  at least 4 16MM projectors and an Elmo TRV16G telecine machine.    As well, I took cinematography in college, and understand film-making well.

You just can't beat a projected film. There is a difference in quality, atmosphere and perception that can't be described!

Any film collectors would well be advise to check out http://16mmfilmtalk.com/ . It's a film collector's forum.   eBay is  a good source for 16MM prints.  Or, I could provide non-eBay sources.  A lot of those sources also  sell 35MM prints.

Jeff......
The film-tech site is GREAT.
Thanks for the info........

Bill

OK Bill, go ahead and sign up on the Film-Tech website.  They'll be glad to have you and then you will be able to post questions, etc.  

Brenkert designed the BX40/80 series starting just before WW-2.  The BX-80 had counter-rotating double disolving rear shutters and the BX-40 had a single rear shutter.  They came out with the BX-60 shortly after the war and it was a little more light weight with the main casting in aluminum, but it was still a rock solid machine.  Brenkert Light Projection Company was in Detroit. RCA bought out Brenkert in the early 50's to compliment their (RCA photophone) soundhead business.   But RCA didn't put much investment into the motion picture business causing it to go out in the mid-50's.

Of note, "Gone With the Wind" (or as the film buffs say: GWTW) premiered in Atlanta on Brenkert projectors.  Brenkert also made an excellent motion picture projection arc lamp, there are examples of both their projectors and lamps still in use in theaters today.

Jeff,
I stand corrected........the company I was thinking about was Motiograph.......great stuff.
I saw more Brenkert lamp houses than I saw projectors......
Some times getting old sucks!
We have to talk more about the "old" stuff........
Bill

Hi Jeff,

That is incredible; having a operational 35 MM cinema projection system in a home environment! I have read about amateur enthusiasts and collectors of this film format, but the thought of the sheer size of the equipment (and the need for a large projection screen) in a residence is impressive to me.

What do you use for loudspeakers and amplification in this system?

In retrospect, it's really no different from those of us who run converted broadcast transmitters in their amateur stations, etc.

73,

Bruce

Bruce, its a pretty modest set up here in the shack.  The screen is approx 4 X 8 feet and the projection throw is about 15 feet.  So I use some short focal length lenses.  Nothing fancy for audio, just a small preamplifier off the solar cell followed by my vintage McIntosh MC-40 amplifiers and a pair of old Marantz tower speakers. 

Like any of this stuff "it's the journey, not the destination" if you know what I mean.  But it's nice to operate the machinery and see the large images.  Your not gonna find first run stuff to project, but trailers and odd reels are fun to look at.

BTW I have a Gates BC TX (BC-1G) in the corner.  HI!