Film-Tech Forum ARCHIVE: CP 55 AUX with sub output

This is topic CP 55 AUX with sub output in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Paul Trimboli (Member # 1509) on 05-23-2007, 06:31 AM:

I know this topic has been talked about before but I could not find an answer to a specific question. Will a standard CP 55 output sub bass when the AUX format is selected? If not how can I enable it?

I was reading about getting 4 channel sound in N/S, Steve Guttag mentioned you can input the stereo signal through "Dolby Tone" inputs, is that by hooking in N/S through the Cat 222 pins 15, 9 and 1?

If the CP 55 does not have an automation card fitted to the back can you wire push buttons into the d type conector J5 to get remote control? I have not seen the CP 55 I will be seting up at this stage so I am not sure what it has but I am just going of the manual.

Posted by Gordon McLeod (Member # 33) on 05-23-2007, 08:53 AM:

I believe that the sub is not enabled in aux mode with the 241
I have often done mods to the card to allow the sub from a DTS player to pass through
The mods are not for the faint of heart

Posted by Larry Zuverink (Member # 1483) on 05-24-2007, 07:15 AM:

You need to purchase a 441 card and be good at soldering. There are several jumpers that need to be soldered onto the back plane. The procedure is in the DA20 manual.

Posted by Mark Gulbrandsen (Member # 72) on 05-25-2007, 10:07 PM:

quote: Gordon McLeod
The mods are not for the faint of heart

Paul would hardly be classified as such... he does far more intricate work than any of us here!!

I would look at the diode matrix on the cat 243 card to do this....

Posted by Tristan Lane (Member # 1169) on 05-26-2007, 02:36 AM:

Is this possible without the Cat441 upgrade? I would think Paul would be able to consult the CP55 & DA20 manuals for all needed modification instructions.

I know that after upgrading to a 441, the sub input in inserted via a pin on the backplane. The same holds true for the right surround signal.

If it's done with the 241 installed, does the aux sub input still go through the EQ?

Posted by Paul Trimboli (Member # 1509) on 05-26-2007, 03:59 AM:

Gordon can you post a description or diagram of what you do to get the sub output?
I will have a L/C/R/S mix and so don't really need to have a seperate sub input just to be able get the sub filter to work in AUX mode.

Mark I though I might be able to turn the sub on using the cat 243 matrix, but was unsure if this would actually work.

Tristan what you asked if really what I need to know, can this be done WITHOUT a cat 441?

Posted by Tristan Lane (Member # 1169) on 05-26-2007, 01:36 PM:

Just an idea:

What if you were to insert the subwoofer signal into pin 14 of the J18 "test" connector? This is the line used by the Cat 85, and will pass the signal through the parametric and fader.

I think the "OBE inhibit" diode would need to be removed from the matrix for the Aux input, and even then, this may have a detrimental effect on normal optical decoding if the aux source is left connected.

If it works, you could use the automation indicator lines to switch the signal on and off with a transistor/relay setup.

Posted by Paul Trimboli (Member # 1509) on 06-13-2007, 09:02 AM:

Is F7 the AUX function on the Cat 243? I will give this a try Tristan and see what I get. Where is the pin out diagram for the J18 Test conector?

Posted by Louis Bornwasser (Member # 3063) on 06-13-2007, 09:55 AM:

AFIK Dolby never published drawings for the CP-55/65.

I have HUGE CP-55 drawings here, somewhere. Louis

Posted by Paul Trimboli (Member # 1509) on 06-14-2007, 06:27 AM:

I found the drawing I was after in the manual. OK so I inputed the LFE through pin 14 of the J18 conector, it worked! The fader controls it when in AUX, BUT it will need to be disconected as the signal is present in the film formats. So I will just hook up a relay/transisitor setup from the automation indicator line and all should be great! I did not need to change any diodes on the matrix to get the OBE to play. This looks like a nice simple solution to getting 4.1 sound into the CP 55. Thanks for the great idea Tristan!

Posted by Tristan Lane (Member # 1169) on 06-15-2007, 09:48 PM:

[thumbsup]

Good to hear! A whole bunch cheaper than a 441 mod!

I gathered all the info for this idea from the CP55 manual. The signal path diagrams were pretty descriptive, and the header pin designations were included in the schematics in the manual.

It's kind of a "backyard" mod, but its nice to know that it get's the job done.

Now, if there were only a way to get split surrounds without a 441.................. [evil]

Posted by Paul Trimboli (Member # 1509) on 06-26-2007, 06:46 AM:

Is there anyway to make the CP 55 Wake with the remote fader selected?