Photo mask by Todd-AO
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| Images and text by: Dan Leimeter, Todd-AO | Date: 18.07.2009 |
| Photo mask by Todd-AO to boost the high end output to 0dB at 12.5K and -1dB
at 16K. Newly developed photographic slit masks for the DP70 optical sound head enable the DP70 to faithfully reproduce audio up to 12.5 kHz at 0dB with little slit loss compensation added in the pre-amplifier stage. This is equivalent to a half-mil slit or less in a forward scan sound head.  The original brass
slits were expensive to manufacture; it was difficult to obtain clean and
straight edges on the sides of the slit, so they were limited in their
high-frequency output. Not only do the new photo slits capture the high-end
frequencies of modern stereo optical sound tracks, they are inexpensive and
easy to install.The new mask should give you a curve that is flat to 12K and down 2dB at 16K. Designed by Dan Leimeter, Bob Weitz, and Rick Barrett, the new slit masks were available from. Todd-AO Studios 900 North Seward St. Hollywood CA USA The photographic mattes were provided free to anyone who asked for them in return for a short written evaluation - good or bad - of their performance. |
Additional dp70 reading here: DP70 / Universal 70-35 / Norelco AAII - The Todd-AO Projector Modernizing the DP70 Internet link: |
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