Film-Tech Forum ARCHIVE: CP65 volume lower...why?

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Posted by Paul Vollmers (Member # 927) on 04-22-2005, 09:54 AM:

On a CP65........what would cause the volume to drop 1.5 numbers on the main fader control.
L C R and suround seem to be working fine but the volume level is lower then last used.
Any ideas?

Paul

Posted by Darryl Spicer (Member # 711) on 04-22-2005, 10:02 AM:

Has a remote fader selection button been pushed or something?

Posted by Mitchell Dvoskin (Member # 751) on 04-22-2005, 10:35 AM:

Exciter lamp/leds dimmer for some reason?

Posted by Michael Schaffer (Member # 1204) on 04-22-2005, 01:03 PM:

The fader knob could just be loose/shifted on the base. In that case, there is no problem with the CP, the knob is just fooling you as to where the fader is.

Posted by Paul Vollmers (Member # 927) on 04-22-2005, 06:37 PM:

Neither main fader or remote fader was not touched....
The exciter lamp voltage is the same....
And the main fader knob is not loose........

could a pre amp be weak..???

now what?

Posted by Brad Miller (Member # 2) on 04-22-2005, 07:31 PM:

Are you playing the same print? Occasionally you get a stupid movie like Charlie's Angels or xXx that is WAY too loud.

Posted by Paul Vollmers (Member # 927) on 04-22-2005, 07:52 PM:

Brad,
I have been running only one test reel with many trailers only.
If the exciter wires were reversed + , - ,on the exciter power supply.......could that effect the volume level at play back?
I was at level 4 on the CP65 fader, and now at level 5 to get the same sound listening level........wierd.

Posted by Darryl Spicer (Member # 711) on 04-22-2005, 08:48 PM:

Wait a tick......are you using a Jax light red led system or a system that requires a line amp between the solar cell and the pre-amps. If so there could be a problem with the line amp.

Posted by Paul Vollmers (Member # 927) on 04-22-2005, 10:04 PM:

I'm using a plain white exciter lamp on a Simplex E7 and a Simplex SH1000 sound head, with a 9V bulb at 7 volts powered by a Kelmar exciter power supply, and a CP65, dolby tone aligned etc...........home screen.

Posted by Brad Miller (Member # 2) on 04-22-2005, 10:28 PM:

Let's back up a minute. What has changed since this problem occured?

Posted by Phil Hill (Member # 371) on 04-22-2005, 11:30 PM:

quote: Paul Vollmers
I was at level 4 on the CP65 fader, and now at level 5 to get the same sound listening level........wierd.

Hopefully you're taking actual SPLs and not just "listening".

Assuming you have measured the voltage at the exciter lamp and it is correct, perhaps the objective lens has dirt/oil on it or maybe the lamp filament has sagged.

Posted by Paul Vollmers (Member # 927) on 04-23-2005, 09:07 AM:

A few days ago I had to move the sound rack several feet.
I disconnected the following wires.
Exciter power wire
two speaker wires
optical sound wires
I made sure that these wires were connected to the same locations on the CP65.
No volume settings were changed at all.
The only question on re wireing was the plus and minus wire to the exciter power supply maybe reversed.......could that effect the volume level?
The exciter voltage is the same.....I checked that.
I also cleaned the optical lens for dirt...none.
After the move.......I loaded the same trailer reel...and noticed the differant volume level.......much lower.
so.......?

Posted by Darryl Spicer (Member # 711) on 04-23-2005, 10:46 AM:

can you run pink noise and set all the sound preasure levels. If you thing two wires are hooked up wrong switch them and see if this changes anything.

Posted by Adam Martin (Member # 641) on 04-23-2005, 12:06 PM:

Did you have to add length to any of the wiring?

Posted by Paul Vollmers (Member # 927) on 04-23-2005, 12:08 PM:

No wire length was added.........just moved the sound rack from one side of the projector to the other side.

Posted by Manny Knowles (Member # 1171) on 04-24-2005, 02:38 AM:

Double check your exciter wiring. You could be out of phase now and that would wreak havoc with decoding, resulting in a level drop (and other problems).

Is dialogue still coming from the centre channel? Verify this by turning off the amplifiers for the other channels.

Also, while you are at it, make sure that the signals from the left and right solar cels are associated with the appropriate processor inputs. In other words, left goes to left, etc. Use a buzz track loop if you have one.

Double check the polarity of all speaker wiring. How many speakers did you disconnect? All of them?

If you disconnected all of the speaker wiring then it would also be worthwhile to verify that each amp is associated with the appropriate loudspeaker(s) in the theatre.

In other words, conduct a thorough examination your A-Chain and B-Chain.

This will make me seem like an insensitive prick, but... I'm curious if you made this move yourself or if some "tech" did this and then left you high-and-dry..?

Posted by Paul Vollmers (Member # 927) on 04-25-2005, 06:13 AM:

I'm thinking that the exciter wireing got reversed at some point, as everything else is correct.
C L R and Sr is working as it should......I double checked the exciter power supply voltage, and it is the same....and Dolby tone is correct on L & R.......checked speaker wires.
BTW, this is in private home theater.

Posted by Richard Hamilton (Member # 321) on 04-25-2005, 07:47 AM:

Paul,
You said the Dolby Tone was correct, so this should eliminate the problem coming from the soundhead. When you moved the rack, did you disconnect all of the components and move them separately? My first thought is that one of the speakers is wired with the polarity reversed. This would create the problem you have. If you rewired the outputs from the processor to the amps, you could have an issue in the wiring there.

quote: Adam Martin
Did you have to add length to any of the wiring?

Adam, on a side note, when we first developed the 35mm conversion kit for the Mega, one issue was the analogue sound. Our only option was a custom analogue penthouse reader. Since we had to delay it a couple of seconds, I suggested we run the signal through a 1000' spool of wire. It would take longer to get to the processor [Wink]

A couple of people thought i was serious!

Rick

Posted by Scott Norwood (Member # 30) on 04-25-2005, 07:48 AM:

Why would the exciter wiring make a difference? Intuitively, I can't see why it would matter--does the filament care about what direction the electricity flows through it?

Posted by Paul Vollmers (Member # 927) on 04-25-2005, 08:43 AM:

Thats a good question....?

Posted by Gordon McLeod (Member # 33) on 04-25-2005, 09:12 AM:

Since the Dolby tone is correct that rules out the soundhead
Either thre has been a failure of the matrix card or a speaker is out of phase
have you verified with a pink noise generator the house levels

Posted by Richard Hamilton (Member # 321) on 04-25-2005, 11:30 AM:

Do you have a pink noise generator? If so, verify each channel separately. If each level is good by itself, then start with one channel of the pink noise and add another. If the level goes down when you add a channel, then there is a polarity issue, you probably swapped (+) or (-) somewhere when you moved the equipment.

Posted by Adam Martin (Member # 641) on 04-25-2005, 12:42 PM:

quote: myself
Did you have to add length to any of the wiring?

I was under the impression that a [poorly made] splice (or nicks in the wire, for that matter) could add resistance to the line and cause a signal drop in the already low level coming out of the soundhead, especially if the conductors are of a different metal or type.

Posted by Richard Hamilton (Member # 321) on 04-25-2005, 01:06 PM:

Adam,
Possibly, but Paul already said that the Dolby levels were set in the processors. These settings would compensate for any descrepancies in the output of the solar cell.

Paul, just a question? Did you have to turn up or down the fader to get the normal level? Your original post is not that clear?

quote: Paul Vollmers
volume to drop 1.5 numbers on the main fader control.
L C R and suround seem to be working fine but the volume level is lower then last used.

Did you change exciter bulbs? Were Dolby levels correct before you moved all of the equipment?

Rick

Posted by Paul Vollmers (Member # 927) on 04-25-2005, 04:02 PM:

Richard,
I had to turn up the fader.....
No bulb was changed.
The whole rack was moved from one side of the projector to the other.....not individual units, amps, etc.

Posted by Paul Vollmers (Member # 927) on 04-26-2005, 05:14 PM:

Last night I took out the cat 242 card out of the CP65 and looked it over....reincerted it, and when I ran a single reel with both DTS and SR, the DTS was way louder................so something must be screwy with that card.

Posted by Brad Miller (Member # 2) on 04-26-2005, 07:57 PM:

Not necessarily. Your jolting of the rack could've knocked the cards loose. It wouldn't hurt to pull them one at a time and reseat them.

Posted by Paul Vollmers (Member # 927) on 04-27-2005, 06:21 AM:

Brad,
I gave that some thought eariler, and did just that, pulled each card and reincerted it.

Posted by Manny Knowles (Member # 1171) on 04-28-2005, 02:19 AM:

quote: Gordon McLeod
Since the Dolby tone is correct that rules out the soundhead

I wouldn't be so hasty to rule out the soundhead wiring.

You can get a good incoming signal with solar cel wires reversed but when a processor decodes an out-of-phase Lt/Rt you will get a bad result. BTW I am talking about the wiring from the cel to the processor (not the power supply to the exciter).

Wherever the problem is found, I would bet that it will be a phase related issue.

I mentioned speaker polarity in an earlier post. Try the tip offered by Richard. Reversed speaker wiring is probably the most likely culprit at this point.

I'm also curious if you observed a level drop with non-sync as well?

Posted by Richard Hamilton (Member # 321) on 04-28-2005, 06:28 PM:

quote: Manny Knowles
You can get a good incoming signal with solar cel wires reversed but when a processor decodes an out-of-phase Lt/Rt you will get a bad result. BTW I am talking about the wiring from the cel to the processor (not the power supply to the exciter).

Is this really true on a solar cell? I know I had a reverse scan with the positive and negative of only one channel reversed and it caused havoc. But on the older systems with solar cells I have never run across that problem.

Of course its been a long time and many beers since my last Solar Cell setup [beer]

Rick

Posted by Manny Knowles (Member # 1171) on 04-29-2005, 02:57 AM:

Me too, I guess. I still call them "solar cels" but I really had reverse-scan in mind.

Posted by Paul Vollmers (Member # 927) on 04-30-2005, 06:47 AM:

Last night I checked all speaker wireing at the speaker...amps..and processor........found all to be correct.
The only thing I can account for is possibly had the wires from the Kelmar exciter power supply reversed.... + -......- + !
Would that create an issue..? and how ?

Posted by Gordon McLeod (Member # 33) on 04-30-2005, 11:51 AM:

You mentioned reinserting the card raised the levels was that back to the original level
Also check the bypass relays on the back of the mother board to ensure none of them have become loose