Film-Tech Forum ARCHIVE: Calibrating Matrix Decoder

This is topic Calibrating Matrix Decoder in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Marin Zorica (Member # 1716) on 01-29-2006, 05:35 PM:

Let's say we have Cat 150, Dolby Pro logic or some other decoder, we got Lt & Rt inputs, L, C, R, S (optional Ls, Rs, Sw) outputs.

How can we calibrate output signal levels??

Let's say like this, if we put 0dB level pink noise tone on input, what level of signals must be on outputs??

I think you get point what i want to ask!

Posted by Mark Gulbrandsen (Member # 72) on 01-30-2006, 08:38 AM:

I would assume that its a unity gain card or very close to it although I have never personally measured the output of one to be sure. It is possuble that the sterring might cause a slight gain difference but again measuring one is the way to really find out.

Mark

Posted by Christos Mitsakis (Member # 143) on 01-30-2006, 10:58 AM:

Marin, setting card's output levels or the actual LCRS sound level in the theatre?

Posted by Marin Zorica (Member # 1716) on 01-30-2006, 12:29 PM:

Yes, I'm interested in card (decoder) output levels, not auditorium levels!

Posted by Gordon McLeod (Member # 33) on 01-30-2006, 10:44 PM:

there is no output level adjustment on the older cat 150 cards
the schematic is in the cP50 manual on line here

Posted by Marin Zorica (Member # 1716) on 01-31-2006, 06:06 AM:

No, i don't mean for cat 150's, but i mean basically how to set any kind of decoder?

Posted by Alan Lyman (Member # 557) on 02-16-2006, 01:41 AM:

If I remember correct,from when I was messing with this,then the L+R channels is unity gain,and the C+S is +3db