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Author Topic: Changing Sound Levels in a CP500 Bonnie Rose Film Handler Posts: 4 From: Homer AK USA Registered: Jun 2012 posted 07-01-2012 07:34 PM                     I recently started working at a theater and the gain on the amps were turn on full after reading the CP500 manual it said sound levels should be around 7. After turning the gain down I tried to reset the sound levels that are already preset and cant figure out how to get to this in the soft keys.My background is in servers and know little about soundracks. Any help will be appreciated. Thanks Bonnie  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 07-01-2012 08:22 PM                     I know this is going to make me seem like an insensitive prick, but... Honestly, you need to hire a professional -- this is not work that you should be doing since it's not part of your skill set. 7.0 is what the main volume should be set to when calibrating at reference level. This is referring to the main volume knob on the front of the CP-500. The actual amplifiers should be at a "known repeatable" setting -- ideally, they would be set to maximum, according to Dolby. (Re-read step one under "Room Equalization") You should return the amps to their original, maximum setting in order to restore the system to what it was before you "messed with it." Luckily your amps were indeed at a repeatable setting -- and this is one reason Dolby makes this recommendation -- people are so often compelled to tinker around back there. Hire a pro -- please.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 07-01-2012 10:37 PM                     Usually, the techs sets the gains open all the way in case an amp needs to be changed out (on the user level where the user just simply open the gains on the local install), not having to worry on coming out and retuning the system for just one amp. It's a lazy habit, but the tech figures that most employees are too scared to touch that stuff, thus can get away with it. That's what a volume control knob is for - too loud, turn it down. I've never seen a CP500 run "7" on any show. It's usually between 3 and 4.2 for normal playback. True, get a tech there since they've been trained and qualified on certain matters. good luck - Monte  |  IP: Logged Bonnie Rose Film Handler Posts: 4 From: Homer AK USA Registered: Jun 2012 posted 07-01-2012 11:52 PM                     So the techs just put it on full gain why not follow the manual. I mean then they could just tell people to put it at the midway setting etc. Also I didnt realize people would be so mean as to refer that I screwed it up. I think that Dolby should put some reference in the manual that the processor may be set at various sound levels. So just one question is it "bad" for the amps to be a full gain over a long period of time. Thanks again  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 07-02-2012 12:36 AM                     Bonnie, Perhaps my first question should've been -- What's going on at your theatre? What has prompted you to make adjustments to your system? There are actually differing opinions on the best method of setting amplifier gain level. Depending on your amps, your speakers and size of the room, it may be necessary to turn the amps down. (It doesn't harm the amps if they are running at max.) Dolby recommends starting with the amp gains at maximum. As stated in my earlier post, that is the first instruction under "Room Equalization," and it appears in boldface type. I'm concerned because you consulted the manual, but somehow missed that. I'm also concerned that you don't seem to understand the difference between the main fader (on the front of the CP500) and the amp gains. There's no other way to put it: That's a serious misunderstanding, and it strongly suggests that you do not (presently) possess a full understanding of what you are attempting to do. (In time, you can learn all of this. But that won't help you right now.) This is why I advise you to hire a professional technician to take care of whatever sound problem(s) you are experiencing. << That's a good, helpful piece of advice. I'm sorry that you think we're being mean to you, but the fact is that your qualifications aren't a good match for this job. Without the proper training, tools and experience, there is a great likelihood that you won't really improve things. You could worsen the situation or cause damage to your speakers. And you definitely won't meet the SMPTE standard by winging it. (I know this because that was me about 12 years ago.) So -- Some questions: Please clarify -- Are you saying that the volume on the front of the CP500 is running at 10? That is the one that *should* be at 7 (not the amps). If you're running everything with the CP500 at 10 that is a problem. Are you using the CP500 to play sound from a digital cinema package? Or are you running 35mm prints? If you're using film, then tell us if you're using the analog soundtrack or digital soundtrack. (If this is a film system, we need to get this thread moved to the Film Handler's Forum.)  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 07-02-2012 12:41 AM                     I tend a 14plex with amps installed when the plex opened 13yrs and they've been at full gain since opening. Nah, doesn't hurt them at all... quote: Bonnie Rose I mean then they could just tell people to put it at the midway setting etc. Why so, is mainly two reasons with a tonnage of other reasons inbetween: 1-techs are in their own business and don't always follow the rules since by experience, they've found ways to make it better, and, 2-there are no two auditoriums/sound systems that are identical in any way shape or form. Each house needs different settings than the other - why no concrete settings can be used..and not intended for user adjustments or diagnostics. Welcome to the forums - you'll learn lots here.  |  IP: Logged Bonnie Rose Film Handler Posts: 4 From: Homer AK USA Registered: Jun 2012 posted 07-02-2012 01:12 AM                     I made the changes after starting here because people were complaining of a rumble and sure enough when we ran The Artist I could hear it. This is a older theatre and so I believe they used some of the old wiring. Anyway after turning down the gain and taking out some of those new type bulbs from the lighting, and changing out the light dimmer the rumble disappeared. The gain was changed as the last ditch effort. Normally I am very very cautious about making changes but we just had alot of complaints. The digital equipment is pretty new here and the person that was here during the install did not have a technical background didnt take any notes and has since left. We are just a 1 screen theatre here in Homer AK and bringing a tech here is EXTREMELY expensive. Thanks Bonnie I am running the cp500 at around 5.5 to 6 (during the movie 4.4 during trailer) since I dont have a really good sound tester. The theatre only holds 210 people in a smaller building which is also metal.  |  IP: Logged Chris Slycord Film God Posts: 2986 From: 퍼항시, 경상푹도, South Korea Registered: Mar 2007 posted 07-02-2012 01:16 AM                     quote: Bonnie Rose I recently started working at a theater and the gain on the amps were turn on full after reading the CP500 manual it said sound levels should be around 7. Please reread the intro to the User's Guide. Specifically... quote: do not adjust any of the controls on the other audio equipment in your theater sound system, such as power amplifiers, which have been preset by your installer.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 07-02-2012 01:21 PM                     Now, since you're not playing "the Artist" anymore and reset your system back to where it was, has the rumble returned? Is the theatre, one of those Quonset Hut layouts (which was a common and inexpensive thing to do to turn it into a theatre and I've seen those before)? If so, that metal really needs to be isolated since it picking up the low frequencies from the sub channel and resonating it everywhere .. like a big steel oil drum.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 07-02-2012 02:00 PM                        By "rumble" do you mean "hum"? As in a constant-frequency noise? Light bulbs would be likely to cause a hum, but not a "rumble." In any case, is the problem in all channels or just one? You can test this by turning off the power amplifiers one by one and then listening to see if the noise is gone. (Obviously, do not do this during a screening or with an audience in the auditorium.) As for adjusting other things, Manny is right. Either get a technician or get the tools and knowledge that you need to not make things worse than they already are.  |  IP: Logged Ron Funderburg Jedi Master Film Handler Posts: 814 From: Chickasha, Oklahoma, USA Registered: Nov 2007 posted 07-02-2012 02:09 PM                        Bonnie Rose if your theater has a regular tech. for it call him in and have him trouble shoot and repair the problem it is his job. If you don' t you need to be in communications with superiors and find out who much they are willing for you to do. It does not sound like you are a trained tech. I do not intend to insult you but things can get really, really screwed up where it takes a lot longer to run down all that has been done put it back right before you find the real problem. If you have to call in a tech after it has been messed up further it is just adding to the cost.  |  IP: Logged Bonnie Rose Film Handler Posts: 4 From: Homer AK USA Registered: Jun 2012 posted 07-03-2012 12:20 AM                     I guess you would call it a hum. I did change out the light bulbs thinking it cause the hum and the dimmer they had installed was just a regular house dimmer that got hot when it was dimmed. Then I went through seeing if it was from the speakers but it just after the gain tweaking that the hum went away. As you can imagine the owner doesnt make alot of money on this theatre and we are pretty much isolated. He did put in some foam barriers on the walls to help with the metal issue. Even after the Artist finished you could hear the hum when any movie got quiet. If any of you know a tech located in Anchorage maybe have him contact me and possibly I could get the owner to pay someone to change the setting for now we are just taking turns running up adjusting the sound level.  |  IP: Logged Chris Slycord Film God Posts: 2986 From: 퍼항시, 경상푹도, South Korea Registered: Mar 2007 posted 07-03-2012 02:18 AM                     Strong Technical Services claims to cover Alaska, at least on the "List your local D-cinema service companies here" section here. So they probably have someone at least semi-locally. 800-424-1215  |  IP: Logged

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