Film-Tech Forum ARCHIVE: Dolby OPU-1

This is topic Dolby OPU-1 in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Richard B. Perrine (Member # 409) on 09-15-2003, 09:22 PM:

I just picked up a Dolby OPU-1 pre-amp.
Would like to fined some prints on the unit and instructions.
Anyone got some knowledge of this unit?

RBPerrine@aol.com

Posted by Gordon McLeod (Member # 33) on 09-15-2003, 09:28 PM:

I think you mean MPU1
I am assuming it is the mag preamp with the silver front cover?

Posted by Brad Miller (Member # 2) on 09-15-2003, 09:40 PM:

The MPU-1 was also made with a grey cover and red stripe to match the CP200 / CP65.

Posted by Chris Hipp (Member # 1788) on 09-15-2003, 09:47 PM:

But you can only use the grey cover after labor day. [Big Grin]

Posted by Peter Hall (Member # 695) on 09-16-2003, 12:29 AM:

There was a pre amp with the Dolby Mono systems installed in the early 1980s (with a C64 and a C22) - was this a OPU1 ?

Posted by Ray Derrick (Member # 1001) on 09-16-2003, 10:33 PM:

The OPU-1 was a 1U rack mount studio optical preamp for use with telecine machines etc. It has been many moons since I laid eyes on one but I think it was stereo and it would have the usual gain and slit loss correction adjustments.

Posted by Sam D. Chavez (Member # 1841) on 09-17-2003, 12:57 AM:

The OPU-1 consisted of input transformers, a Cat. No. 108 preamp, metering for Dolby level and line drivers to get up to 0 dB line level.

This was well before the Cat. No. 240 came into existence. I've converted a few SA3/4 frames to take a Cat. No. 240 for use in studio and telecine applications where you need a true optical preamp.

Posted by Richard B. Perrine (Member # 409) on 09-17-2003, 08:24 PM:

This one has optical stereo inputs for 2 machines (labeled "E + -)......the Cat 108-4 pre-amp card and a Cat 137A output card.

On the back of the unit are the projector input strip, output terminals and 2 lugs labeled remote.

Need some info on it.....like changing from proj 1 to 2 for change-overs.
Would really like to have a book on it.

RBPerrine@aol.com

Posted by Sam D. Chavez (Member # 1841) on 09-17-2003, 11:18 PM:

You are correct, it is a two projector device. The Cat. No. 137 was used as a line driver. The remote pins are for the changeover. Maintain contact for projector 2.