This is topic CP65 question in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Greg Mueller (Member # 17) on 11-02-2001, 09:01 AM:
Is there a switch or jumper than can be thrown that will turn on all the speakers in "Mono" mode?------------------
Greg Mueller
Amateur Astronomer, Machinist, Filmnut
http://www.muellersatomics.com/
Posted by Pete Naples (Member # 761) on 11-02-2001, 09:27 AM:
*rakes memory*No, not on a CP65, the CP45 has 'mono enhance' which uses all the stage speakers. With a CP65 I suppose one could shimmy some diodes about on the logic card. To what end do you wnat to achieve this?
Posted by Greg Mueller (Member # 17) on 11-02-2001, 09:45 AM:
Turning on all the stage speakers is just what I had in mind. I just want a little fuller presentation. I really didn't want to get into soldering and modifying cards. I was just hoping there was a switch or something that would give me "wide mono"------------------
Greg Mueller
Amateur Astronomer, Machinist, Filmnut http://www.muellersatomics.com/
Posted by John Walsh (Member # 168) on 11-02-2001, 10:09 AM:
Several people have wide mono before, and generally feel the sound loses clarity (although it does sound fuller.)
Posted by Bob Healey (Member # 1003) on 11-02-2001, 01:43 PM:
One thing that might or might not involve soldering depending on your setup, is to insert a switch box between Center out on the CP65 and your amps. In one position the switch sends the sound to only the center amp, in the other position the switch sends the signal to whichever channels you choose.
Posted by Gordon McLeod (Member # 33) on 11-02-2001, 03:20 PM:
Get a used Kintek or Smart stereo generator.
The older Kinteks were very good and effective and the DBX expander worked well on those old compressed mono tracks
They show up on EBAY a lot
Posted by Gordon McLeod (Member # 33) on 11-02-2001, 06:58 PM:
I don't have the info with me but I believe that there is a selection for LCR to be active in mono and it was documented in the installation book
Or maybe my brain is just to fried
Posted by Steve Guttag (Member # 268) on 11-04-2001, 09:13 PM:
Since the logic of the CP-65s was to "inhibit" channels to turn them off...cutting the INHL and INHR diodes for the mono format will probably give you a 3-channel mono. I believe that the Cat. 242 actually comes with mono going to all three channels at the MUX chips and uses the inhibit function to kill the L and R channels.As a side/sad note...Dolby has officially discontinued the CP-65!
This is truely the end of an era. The Cat 64 (though in their B variety now) equalizers used in the CP-65 date back to the father of the Dolby cinema processors the "E2" which was combined with the Model 364. The Cat. 64 found homes in all of the cinema processors since until the digitally based CP-500 came out in the mid 1990s. That is a pretty damn long run for a piece of electronics today...about 30 years (give or take a year). The CP-65 can really trace it's roots and signal methodology just about all the way back. It is the last Dolby cinema processor that had an open backplane (no longer allowed in some countries). Good bye old friend, you have served the industy well.
Dolby now only offers the CP-650 and the CP-45.
Steve
------------------
"Old projectionists never die, they just changeover!"
Posted by Gordon McLeod (Member # 33) on 11-04-2001, 09:24 PM:
That is sure a case of extremes
Posted by Scott Norwood (Member # 30) on 11-05-2001, 06:14 AM:
The CP500 is discontinued, too? Wow. I'm surprised that Dolby doesn't seem to think that there is a substantial market for high-quality analog-only installations... (Or maybe it was the glut of used equipment that represents the real problem.)
Posted by Richard Hamilton (Member # 321) on 11-05-2001, 06:24 AM:
Doesn't putting the unit in Bypass send everything to LCR?
Posted by Richard Fowler (Member # 893) on 11-05-2001, 06:59 AM:
The CP-500 is available in very limited situations such as for QC in laboratories.It was retired in favor of CP-650 and to insure a stock of parts for the existing CP-500 units in the field....
Richard Fowler
TVP-Theatre & Video Products Inc. www.tvpmiami.com
Posted by Scott Norwood (Member # 30) on 11-05-2001, 09:19 AM:
Good point about 'bypass'--it works that way on the CP50, but I don't remember if it does on the CP65. Still, you'd lose the EQ functionality (and, on the CP50, the fader, too).
Posted by Pete Naples (Member # 761) on 11-05-2001, 03:47 PM:
Steve, that's excactly what I was thinking of too!WOW No more CP65 
( I have the first two ever made in the UK under my care in Edinburgh, interesting that the basic technology can be traced back so far, and doesn't it work well!?.
The CP500 has, I believe, only been available from stock for some time now, but they kept telling us they'd make a bunch of them every so often. It would follow that the DA20 will shortly go the same way. Which means that if you bought a CP65 or CP45, or have a CP55 with the intent to do Digital later..... You gotta start all over again
Posted by Greg Mueller (Member # 17) on 11-05-2001, 04:36 PM:
Bob Healey suggested that I put a switch in to feed L&R channels off the Center output. Would it hurt anything to just use a couple of aligator clips (or jumpers) to short the L&R output to the Center? Would it do any damage (back feed??)to any of the circuits, do you think?------------------
Greg Mueller
Amateur Astronomer, Machinist, Filmnut
http://www.muellersatomics.com/
Posted by Bob Healey (Member # 1003) on 11-05-2001, 04:52 PM:
I have not tried that switch, so I do not know if there would be any pitfalls associated with it. It is one of the few things we have not rigged a series of switches for. We don't run mono enough to make it worth seriously investigating.
Posted by Greg Mueller (Member # 17) on 11-05-2001, 05:12 PM:
Right, and that's kinda why I didn't want to do any slicing and diceing to the cards------------------
Greg Mueller
Amateur Astronomer, Machinist, Filmnut
http://www.muellersatomics.com/
Posted by Bob Healey (Member # 1003) on 11-05-2001, 06:05 PM:
If I were to attempt it, I'd use two switches mechanically rigged so that they both had to be in the same position. I'd cut the L C R lines between the output terminals on the CP65 and the input terminals on the power amps. One switch would be a double pole switch and be inserted into the L and R lines with L on one pole and R on the other. When the switch is closed, L and R can get from the CP65 to the amps, when its open, the L/R terminals on the processor are isolated. The second switch would be a double throw switch of some type. In one position, C on the Dolby would pass through the switch to the amp, in the other position, the feed from C on the dolby would be split three ways into each power amp, downstream from switch on the LR lines to prevent feeding C into L/R out on the dolby.
Quick and dirty sketch done in paint brush:
Posted by Greg Mueller (Member # 17) on 11-06-2001, 09:18 AM:
Good idea, I'll do it------------------
Greg Mueller
Amateur Astronomer, Machinist, Filmnut
http://www.muellersatomics.com/
Posted by Bob Healey (Member # 1003) on 11-06-2001, 12:34 PM:
Just remeber my previous post is all theory and has not been verified.
Posted by Ray Derrick (Member # 1001) on 11-07-2001, 05:48 AM:
There is an easier way with just one DPDT switch. 
You could substitute a relay with DPDT contacts for the switch and drive the relay (via a suitable buffer) from the Mono indicator output from the CP65. This would ensure that the system was put back to normal whenever Mono is not selected.
Also note that sending the mono signal to the left and right channels as well as centre will result in an increase of 4.77dB in SPL. So it will be necessary to pull the CP65 fader back about a notch and a half to compensate.
Ray Derrick
President
Panalogic Corporation Pty Limited
44 Carrington Road
Castle Hill NSW 2154 Australia
Phone: 61 (0)2 9894 6655 Fax: 61 (0)2 9894 6935
Posted by Greg Mueller (Member # 17) on 11-07-2001, 09:01 AM:
Excellent!
Having to roll off the gain 1-1/2 would be just about right as I have to run everything else at 5-1/2 or it's too loud anyway. This is gettin better all the time.
Thanks------------------
Greg Mueller
Amateur Astronomer, Machinist, Filmnut
http://www.muellersatomics.com/