Why change a technology that has worked so well?

First, for years the one hour photo shops have used a three step process to develop color film. It currently takes about fifteen steps to make a 35mm release print. Problems associated with silver soundtracks are one of the major causes of waste in the laboratories. Eliminating the silver soundtrack will simplify the developing process, save water, and reduce the use of caustic chemicals in our laboratories.
Second, removing silver application and the associated processing chemicals from 35mm prints is an environmentally responsible thing to do. A typical 35mm print contains about 250 parts per million silver content due to the silver soundtrack. Every year millions of pounds of film is deposited into landfills or incinerated. The silver is lost and the trace amounts of caustic chemicals involved in processing the silver soundtrack are introduced into our environment.

If we do not use a silver emulsion what do we use?

For several years Eastman Kodak, Dolby Laboratories and Technicolor have been perfecting a process to produce a silverless soundtrack utilizing the cyan color dye layer. Of the three color dye layers, the cyan layer is the best candidate to replace the silver soundtrack. It has the best resolution and is compatible with readily available light sources.
Silver soundtracks block the entire spectrum of visible and infrared light. The cyan dye layer, however, will only effectively block a narrow spectrum of red light.
Tungsten bulbs emit a wide spectrum of light, predominately infrared. Only a tiny portion of the tungsten bulb output is effectively blocked or modulated by a cyan soundtrack. The rest of the light energy passes through and is modulated only by the dust and dirt on the surface of the film. In addition, tungsten bulbs have relatively short life, and have filaments that tend to exhibit uneven illumination and sag over time. Clearly, an alternative light source needed to be found.
Fortunately, LED technology has made tremendous strides during the last decade. Modern stoplights are now equipped with red LEDs and huge LED signs now display brilliant, colored images. Typical red LEDs have their maximum energy precisely where the blocking effect of the cyan layer is most effective. Red lasers are an alternative. Although they emit more intense light than LEDs, they require more complex circuitry to operate them.
It should be noted that today all the digital formats use red LEDs to read the digital data. The majority of the analog readers, however, still use the old tungsten Exciter lamps.

What happens when a cyan analog soundtrack is played on a standard projector?

First of all, if the projector is equipped with a tungsten Exciter lamp the cyan soundtrack will play back with about one quarter the normal volume. Even with your sound system cranked all the way up the sound will still be below normal. To make matters worse, the dust and dirt noise from the film will be vastly increased. All in all your sound presentation will be pretty poor. If your projector is equipped with a red reader the cyan track will sound about the same as the current silver soundtracks.

When will cyan soundtracks be here?

The recent release of City of Angels contained a number of test prints made with an intermediate silver process called High Magenta. In the next few months many more prints will be made with this process. These prints are more compatible with both tungsten and red light sources than standard silver soundtracks. When a sufficient number of theatres are converted to red readers, then we will see the emergence of silverless cyan soundtracks. This will probably occur near the end of 1999. To minimize costs theatre owners should consider converting theatre complexes to red readers during regular technical maintenance visits over the next eighteen months. In any case the new red readers are a good investment. The sound quality is better, they consume much less power, and the long life LED or laser lamp eliminates one more theatre maintenance item--the tungsten Exciter bulb.

What red analog readers are available for theatres?

1. Dolby™ Red LED analog readers
A few years ago Dolby Laboratories introduced a new reverse scan technology which significantly improved the reproduction of analog soundtracks. The long life LED light source evenly illuminates the soundtrack area and consequently reduces distortion. The reverse scan design also improves channel separation and frequency response with only a slight increase in dust and dirt noise.
Nearly all new projectors already come equipped with red LED readers. Existing projectors can also be retrofitted with these readers. Installation takes about one to three hours. The soundhead will need to be rebuilt. The Exciter lamp assembly, slit lens, and photocell must be removed. An LED lamp is installed where the photocell was and a new lens and photocell assembly is installed where the slit lens was. In addition, a preamp and new remote power supply must be installed.

2. CCD Analog Readers
Within the next few months a new reverse scan device will be available. This device uses a red LED source and sophisticated CCD reader circuitry. The CCD scans the soundtrack area, reading just the audio information while substantially ignoring dust, dirt, splices, and scratches. Virtually perfect channel separation is achieved by scanning and compensating for the side to side weave of the film. Installation of this device is expected to take one to three hours. It also involves rebuilding the soundhead. An LED lamp is mounted where the photocell was. The lens and CCD reader assembly is installed where the slit lens was and a new remote power supply must be installed.

3. Red LED Exciter Lamps
Ultra-Stereo Labs, Inc./USL, Inc. recently introduced a red LED Exciter lamp replacement. This device directly plugs into the existing Exciter lamp socket and requires no modifications or replacement of slit lens, photocell, or Exciter lamp power supply. The installation is simple and requires only a small booster amplifier to be installed at the projector. Both the amplifier and LED Exciter lamp are instantly replaceable, if necessary. Sound reproduction is superior to standard tungsten bulbs due to the very even illumination of the long life LED light. Virtually any theatre converted to stereo within the last twenty years should easily achieve wide, flat frequency response comparable to other types of red readers.

4. Red Laser Analog Readers
A few years ago, the Raytheon company developed a Laser sound reader to reproduce analog soundtracks. These are now standard on the new Ernemann projectors. They feature extended high frequency response and long life.
In addition, a Japanese company is introducing a new line of Red Laser Slit Lenses that fit most projectors. The manufacturer claims extended frequency response and long life. Existing soundheads will need to have the Exciter lamp assembly and slit lenses removed to accommodate this new lens. Existing photocells should be able to be used. Installation is expected to take 1 to 2 hours.

Summary

Cyan soundtracks are coming, there is no doubt. They promise to reduce the number of defective prints which will improve presentation. They will also be one more step in improving our environment and conserving resources for the next millennium. We all need to do our part now to make this conversion as painless and efficient as possible.