I got this answer from Film-Tech.com about the stereo speakers:
a lot of drive-ins were designed and built for cinemascope, the field was wired for three channels (left center and right, no surround channel was used ) A standard penthouse was installed and three channel amplification. Eprad made a nice three speaker unit that you placed on the dashboard of your car and it supplied the three channel sound. Drive-ins wanting to save money used standard mag penthouses but blended the three stage channels into the one mono channel. Some indoors did the same thing to save money and still be able to play the mag only soundtracks on the early scope pix. I have a simplex penthouse with a factory ‘4-CH / Mix’ switch built in. As well as a blue colored Eprad 3 speaker unit in my collection.
This opened as the Lotus theatre on December 25th, 1920 and reopened as Towne on November 16th, 1931. renovated and reopened on December 28th, 1954. Three grand opening ads can be found in the photo section
This reopened as The Movies on September 5th, 1968. Grand opening ad in the photo section.
This was to open on March 16th, 1969 but its opening was postponed until June 25th, 1969. Grand opening ads in the photo section.
Reopened as Capri theatre on August 7th, 1963. Grand opening ad in the photo section.
I was unable to find listings for this drive-in from 1957-1964 in The Call. Reopened on June 10th, 1965. Grand opening ad in the photo section.
Reopened as Jeanette on May 3rd, 1957. Grand opening ad in the photo section.
I got this answer from Film-Tech.com about the stereo speakers:
a lot of drive-ins were designed and built for cinemascope, the field was wired for three channels (left center and right, no surround channel was used ) A standard penthouse was installed and three channel amplification. Eprad made a nice three speaker unit that you placed on the dashboard of your car and it supplied the three channel sound. Drive-ins wanting to save money used standard mag penthouses but blended the three stage channels into the one mono channel. Some indoors did the same thing to save money and still be able to play the mag only soundtracks on the early scope pix. I have a simplex penthouse with a factory ‘4-CH / Mix’ switch built in. As well as a blue colored Eprad 3 speaker unit in my collection.
This opened on October 8th, 1954 with the world’s largest CinemaScope screen. Grand opening ad in the photo section and below.
Found on Newspapers.com
This opened on August 14th, 1954. Ad claims that it had the first new outdoor CinemaScope and stereophonic installation in the world.
How did they get stereo sound from the mono speakers at the time?
Found on Newspapers.com
August 13th, 1954 grand opening ad in the photo section.
Opening date was October 19th, 1949
Grand opening ad in the photo section as well as below:
Found on Newspapers.com
This opened as Route 45 Drive-In on June 26th, 1946. Grand opening ad in the photo section.
This reopened as Cinema on April 12th, 1941. Grand opening ad in the photo section.
Found on Newspapers.com
Became Boyd on November 27th, 1938.
Found on Newspapers.com
Found on Newspapers.com
This opened on October 19th, 1936 Grand opening ad in the photo section and below
Found on Newspapers.com
August 31st, 1933 grand opening ad in the photo section.
This opened as the Lotus theatre on December 25th, 1920 and reopened as Towne on November 16th, 1931. renovated and reopened on December 28th, 1954. Three grand opening ads can be found in the photo section
This opened on February 4th, 1929. Grand opening ad in the photo section and below:
Found on Newspapers.com
Reopened as Transit theatre on May 25th, 1931. Ad in photo section.
Article:
Found on Newspapers.com
This opened as Cameo on November 15th, 1927. Grand opening ad in the photo section.
This opened on October 11th, 1926. Grand opening ad in the photo section.
April 2nd, 1921 grand opening ad in the photo section.
Grand opening ad in photo section and below.
Found on Newspapers.com
October 6th, 1917 grand opening ad in the photo section. Opened on the 8th.