Questions about cinema sound!

The Mayfair theatre plays films in a number of different sound formats depending on the age of the film and what sound format it supports.


1930’s- 70’s


Early films mainly before the mid seventies generally only have a mono optical track on the film. So classics like Casablanca, early bond films, the Wizard of Oz where mixed Mono, which means only the centre speaker behind the screen plays the sound.

60’s – 80’s

Magnetic sound

In the 60’s when cinema scope and 70mm epic films were introduced a multi track magnetic sound format was introduced. This system was either 4 track (35mm) or 6 tracks (70mm) and sounded vastly superior to the single mono optical track. The format however was never widely     adopted  and has become obsolete.

Dolby Stereo (Dolby A)


About the mid 70’s some bigger budget films started having Stereo tracks. This optical track called “Dolby A” could support up to 5 channels, Left, Right, Centre, Sub and a Mono Surround. This format became the standard in cinema till th early 90’s

Dolby SR (Spectral Recording)


In the early 90’s Dolby came out with a new optical stereo format called Spectral Recording, or Dolby SR. This was still a 5 channel optical track with mono surrounds but it had better noise reduction and dynamic range. This is now the standard for optical tracks on 35mm film. All new films will have this track on the film.

Digital 6 track sound

During the early 90’s a number of 6 track digital sound formats came to the market. The main ones are Dolby Digital (6 tracks with split surrounds), DTS (Digital Theatre Sound, also 6 track), and SDDS a Sony digital format that could support 7.1 sound. Sony has stopped making the processors for SDDS though, so the format will become obsolete. The Mayfair now has both DTS and Dolby Digital. DTS sound runs off a CD or DVD that syncs to the 35mm film. The great thing about DTS is if the print is dirty or splicy the sound will still be perfect. The major draw back to the system is that if the distributor does not send the discs with the film you no have no digital sound (which happens a lot!) Dolby Digital works by encoding digital information that is embedded between the sprockets of the film, so no CD/DVD is needed.

Video formats?

When we run videos rather then 35mm film, it will either be 2 channel stereo (low-budget docs or independent films) or 5.1 Dolby Digital

16mm sound formats

16mm films have always been Mono

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