Film-Tech Forum ARCHIVE: Dolby optical pre-amp cards

This is topic Dolby optical pre-amp cards in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Stephen Furley (Member # 1277) on 11-07-2003, 04:48 AM:

What is the difference between the Cat. 108 card used in the CP-50, and the Cat. 240 used in the CP-55 and 65? Is it possible to use a Cat. 240 in a CP-50?

Posted by Mark Gulbrandsen (Member # 72) on 11-07-2003, 08:33 AM:

Stephen,

Which CAT 240 do you have? There is one that is transfomrer coupled(has a square input transformer eight on the PCB CAT 240) and a later one that I believe is direct coupled with no transformer CAT 240A. There is a HUGE difference between them, and in the slit loss frequency action between the two.

Similar differences will be found on the CAT 108 vs. the CAT 108C for the CP50/200

At any rate Panastereo is making the best optical preamp(processor for that matter) on the market no holds barred! So if you're thinking about adapting some other board consider theirs first but be sure you can attain the required needed levels to drive the CP without alot of. Having worked with all of the major processors in the last couple of months I can definately attest to that.

Mark @ CLACO

Posted by Steve Guttag (Member # 268) on 11-07-2003, 08:41 AM:

Thre is very little in common between the Cat. 240 and the Cat. 108.

The Cat. 108 used external transformers, the the Cat. 240 has them onboad (and the Cat. 240A, as Mark stated is direct coupled to transistor inputs).

The Cat. 108 used discrete componetry, the Cat. 240 uses ICs mostly.

The pinouts are not the same so you can't plug one in the place of the other either.

Steve

Posted by Stephen Furley (Member # 1277) on 11-07-2003, 09:15 AM:

quote:
you can't plug one in the place of the other

I thought that would be the case, but it couldn't do any harm to ask.

There is an old CP-50 which I could borrow from somewhere, but it is missing the 108, (and a few other bits) I wanted to use it at home for a few days, connected to an old soundhead to listen to some old mono tracks, probably only on headphones.

In my case of tools and spares which I carry around when I'm doing any projection work I have a spare 240, and I hoped I might be able to use that. Forget about the CP-50 then; maybe I can wire the cell into the amp in an old Bell and Howell 16mm machine, I'm not worried about sound quality, as long as I can make out the commentary it'll be good enough.

Posted by Peter Hall (Member # 695) on 11-07-2003, 11:35 AM:

HI Steven -

If you have a 240 then you should be able to hook it up to a PSU - sometimes the LtRt outputs will drive a set of headphones.. Otherwise feed the outs (ideally via tx) to a line amp

Or buy one of my CP50s !!

Posted by Bruce Hansen (Member # 281) on 11-07-2003, 12:02 PM:

If you just want to listen to old mono tracks, then you do not need any noise reduction (A or SR). Just connect the cell output to the mike in on a mixer (do not use mag phono inputs, the EQ is all wrong).

Posted by Chris Trainor (Member # 9) on 11-09-2003, 04:08 PM:

Even if you want to listen to stereo prints doing that isn't a bad idea. I used a DJ mixer for a while before I got a cinema processor on my home system. Took the left-right outputs from the cell and ran them into the 2 microphone inputs on my RatShack DJ mixer then sent the outputs from the mixer into a 1octave EQ then onto a 200watt DJ amplifier. Worked. Sounded decent as long as the print was clean. Only really tried it with A type prints tho, not quite sure how SR would sound.

--Chris

Posted by William Hooper (Member # 71) on 11-01-2004, 06:15 AM:

How many Cat. 240 cards have failed on you?
What's the usual failure mode of the Cat. 240?

After finally no longer being intimidated by the slot for the "Spare Cat. 240", one finally went out on me. It's failure mode was inability to switch to projector 2 on changeover (when the Cat. 240 c/o circuit was closed).