Film-Tech Forum ARCHIVE: Can you fade out from non-sync to SR on a Dolby CP55

This is topic Can you fade out from non-sync to SR on a Dolby CP55 in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Stephen Frazza (Member # 2320) on 06-12-2006, 01:49 AM:

When my Dolby CP55's switch from non-sync to SR when the movie starts, they music from my cd player on the non-sync format stops abruptly.
Is there a way to make it fade out so it sounds like a smoother transition.
The CP's are taking their pulses from Strong SPA-7 automations.

Posted by Monte L Fullmer (Member # 2797) on 06-12-2006, 02:33 AM:

I have basically the same setup - CP-55's, only with CPA-10's (which the SPA-7 was a simpler version of the CPA-10..from STRONG..).

Unfortunately, with any automation sending a pulse down to any processor to do the immediate sound switching from non-sync to feature, one would have to come up with a outside fader unit between the CD player outputs and the non-sync input of the CP-55 to do the fading request that you desire..and this would have to come BEFORE the press of the start button..

You might have to do the fadedown manually before you press <start> ...

-Monte

Posted by Ken McFall (Member # 845) on 06-12-2006, 02:23 PM:

There is indeed a way of doing what you want. However it has an added effect which slow's the reaction of the manual fader.

The modification requires changing two resistors.

The effect is that when you press the 'MUTE' button the sound fades out slowly in about 5 seconds. When you press any format button, the sound is rapidly retored to what ever format was selected.

For automation use you would cue the mute with a cue as the projector starts. When the shutter open's you would have sound as normal.

Switching between formats works as normal.

It's a simple mod but requires soldering on a pull out board.

The auto fade works at all times. However the manaul fader lags as you manually fade.

This mod was given to me by Dolby and is still in use after about 9 years.

Now for the bad news..... I can't find the documentation anywhere! If I do find it I'll post here.

If you contact Dolby and speak to one of their tech's explaing you want to modify the mute button charachterists I'm sure they will be able to help.

Posted by Christos Mitsakis (Member # 143) on 06-13-2006, 02:01 PM:

By replacing R34 on Cat 243 with a higher value resistor you can modify the mute button fadeout time.