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I have been off and on trouble shooting this noise that comes over our PA speakers. Its a AC noise, sounds like something is shorting out. Only wish it has, then I would be able to fix it. This noise is erratic, it happens at different times and for different intervals. So I have been reading some of these forums and noticed I am not the only person with this problem. Ill list things that I have done.
Valcom 2003A PA System, ( 12 ) 24 volt drop ceiling speakers, 10 Bull horn speakers and 2 separate power supplies. We also have a radio receiver playing call on hold music. This music is also played in our production area through the bull horns. We have disconnected the receiver but still have the noise. Our phone system is located in our server room. All computers seem to be running good. You would think if a computer component is shorting bad things would be happening.
This noise never happens over the Bull horn speakers.
1. Disconnected speakers one at a time. Ran though all the runs and noise never stopped. All speakers have separate run to the 66 block.
2. Physically checked all cables running to the 66 block. No nicks ( from mice or snags ) no runs are running parallel with high voltage. No runs are laying over any light fixtures. All runs are cat 5. Ungrounded per Valcom. The longest run is maybe 60 foot. There are no motors or such in our drop ceiling.
3. Disconnect tip and ring from PBX
4. Replaced all power supplies
5. Replaced Valcom 2003A controller
6. Disconnected tip and ring from all speakers
7. Pulled a isolated 120 volt grounded circuit for the entire phone and paging system.
8. Bypassed the UPS
9. Replaced 66 punch down blocks for both speakers and for Valcom 2033A.
10. Pulled new cat 5 wire for all speakers
11. Replaced surge protector
12. Disconnect bull horns from PA system
13. Disconnect drop ceiling speakers from PA system. No more noise. But noise never happens over bull horns anyways.
Valcom says there is no way of testing each speaker. As I said before I have disconnect each speaker 1 by 1 and the noise is still there.
Now here is something interesting. We have about 50 digital Panasonic telephones in our plant. Only one phone will pick up this noise. This phone is located in our break room. If I disconnect the phone run at the 66 block, I still here the noise, even over the disconnect phone. We have 2 vending machines, noise existed before these vending machines arrived. We have a refrigerator but there is no correspondence between compressor starting and when we hear the noise. I have traced this run back to the 66 block. Again nothing wrong with the cable and no motors or cable laying on light fixtures. I could really use some more things the look at here. Ive done every thing that I can think of except find the problem. Oh, our telephone provider was absolutely no help. Valcom states Ive checked all that they know to check.
Jason
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You said two power supplies and the noise is only on the ceiling speakers.
Do the bull horns use one power supply and the ceiling speakers the other? If yes then check the power supply and power cables. My guess is the power is intermittently shorting to ground or some thing that it shouldn't.
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Now, one power supply powers the bull horns and the other supplies the ceiling speakers. As I mentioned in my first post. Power supplies have been replaced and all new cat 5 cables have been pulled to the speakers. ![frown frown](/forum/images/graemlins/default/frown.gif)
Jason
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Is the noise a low hum? You said it sounds like something shorting out, so do you mean clicking? These things usually pick up AC induction, which would be a hum. If that's what it is turn off the breakers one at a time until it goes away. That will at least let you know what circuit is causing it. Also if it is AC induction shielded speaker cable grounded on one end should fix it, you're gaining nothing using CAT5. You could try grounding all the unused pairs in your CAT5, one end only and make them common to ground.
Retired phone dude
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Its not a hum like a ground loop hum. Its is more like crackling, like the sound you hear when welding. Speaking with Valcom the OEM, they state shielding the speaker run is not necessary. We all know that the OEM does not always no best, so it might be worth a try to shield the cable. This system has been up and running since 2001. Just last year 2011, no building change, this noise starts. I would like nothing better then to start throwing breakers. My issue is the breakers I need to throw, control our computer systems and offices. The second issue with throwing breakers, this noise is so erratic that we can hear the noise only once a day. Maybe the next day 4 times, maybe 30 times in one day. This noise follows no suit so I cant relay it back to any type of AC that would start and stop like that.
Jason
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Wouldn't hurt to ground your unused pair to see if it would help.
Retired phone dude
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Unless the horns and ceiling speakers are different audio feeds the problem has to be in the power. Try plugging the power into a different AC circuit. A good way to test if noise is being picked up by audio pair is when the noise is happening short the audio pair together and see if it stops.
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I did disconnect tip and ring on all the speakers. Noise is still here, so it is on the power side. I did pull a isolated 120 volt circuit to the phone system and replaced power supplies. I'm thinking the issue lays between the punch down block and the speakers. But what????????????????????????? No motors, wires are high and tight. No nicks.
Think I am going to try what Bill suggested and ground all the unused pairs of the cat 5.
Jason
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RIP Moderator-Mitel, Panasonic
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Remember that since all the drop ceiling speakers are (apparently) in a separate zone from the horns, you are running two of the 3 zones. ANYTHING that gets on the speech pair from any speaker is going to ALL the speakers, but not to the horns. Also, it would seem that you still have 1 unused zone in the 2003. Move the speakers to it and see what happens.
When I was young, I was Liberal. As I aged and wised up, I became Conservative. Now that I'm old, I have settled on Curmudgeon.
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We are using all 3 zones. The controller was replaced already so I think its safe to say not a controller issue. Zone 1 Bull horns, Zone 2 upstairs offices, Zone 3 lower offices.
Jason
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OK so do you hear the noise on zone 2 and 3 but not zone 1?
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Yes. I have removed all but 1 zone and move it to the other zones. Ceiling speakers make the noise on any of the zones. Bull horns do not.
Fun huh? If I had longer hair I would be pulling it out.
Jason
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If I got this correct you have removed the audio pair from the speaker, replaced the power cable, the 2003 controller, the power supply and connected it to another AC source but you still get the noise.
Double check all the wiring and make sure something didn't get crossed up in all the changes. Connect a horn to the same circuit as the ceiling speakers and see if it makes the noise. Does noise volume change with the speaker volume control?
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I just finished grounding the extra pairs of wires in the cat 5 cables as Bill suggested. Going to give it a day or so to see if this has helped.
Volume does change the noise level.
At one time I have connected all the speakers to the same zone. Ceiling speakers made the noise but the bull horns did not.
Jason
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Could it be RF that the ceiling speaker amps are sensitive to but horn amps not?
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RIP Moderator-Mitel, Panasonic
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Merritt, if the building is 'Red Iron' construction and poorly grounded,that would certainly explain it.
Suga Ray Jay, try turning all the speakers down 10 degrees on their potentiometers. Hardly any drop in perceived audio level, but that last 10 degrees REALLY opens up the gain and input sensitivity.
When I was young, I was Liberal. As I aged and wised up, I became Conservative. Now that I'm old, I have settled on Curmudgeon.
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Grounding the cat 5 cables did not work. Seems everything I'm doing is helping, but just not fixing it.
Lightninghorse, Are you referring to the master volume on the 2003A or each individual speaker? Again this system has been working well since 2001 with out any problems so I'm not sure red iron is a factor. But I'm willing to try anything.
Jason
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RIP Moderator-Nisuko-Tie, General
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I'm willing to try anything. you've replaced a bunch of stuff ($$$) spent a lot of time and are getting nowhere . why not call in a pro ? I would
Skip ------------------------------------
Serving SW and West central Fl since 1984
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We used to run shielded single pair to the ceiling speakers because you never knew how close they would come to who knows what type of electrical devices or circuitry. We would terminate them on a 66 block equipped with a ground strap terminated at building ground. We then would take the shields and terminate them only on the 66 block ground strap.
Forty six years and still fascinated with Telecommunications!
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All the PRO's including the phone company are no help. Velcom, phone company and a audio video specialist have told me they don't know either. Phone company has been here many times, in fact they installed the system.
Jason
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If you know any PRO's in the north western WI or ST Paul MN area I would be more then willing to call them.
Jason
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OK, let's think about this. SOMETHING has changed. It's "PROBABLY" not in the paging system. It's interference 'in the air' so to speak. Has ANY other equipment been added, worked on, installed, or removed, in or NEAR the building? AND THINK ABOUT TRANSMITTERS OF ANY TYPE!
When I was young, I was Liberal. As I aged and wised up, I became Conservative. Now that I'm old, I have settled on Curmudgeon.
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Suga Ray Jay- our Tech Support team here at Valcom is grasping at straws, as is everyone else! Let's try something. What if you lift the speaker (while still connected) above the ceiling grid. Does the noise go away?
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If I'm not mistaken a AT&T cell tower went up. Not sure how long ago. We added a new phone and voice mail controller, but that was at least 4 to 6 months before the noise started. I have our IT person looking into dates and equipment that was installed around that time. Equipment that we have and has been running before this:
Computer Servers ( Wire less ) Video Surveillance ( I believe some is wire less ) Heating and cooling Zone controller ( Damper motors ) 1 Bathroom vent fan, runs constant.
Jason
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The noise is not constant. I could possibly have to stand on a ladder for hours waiting for the noise. I suppose I could take every speaker tile and turn them 45 degrees and set them back on top of the grid instead of in the grid. Would that give you what your looking for or would the speakers still be to close to the grid?
Jason
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Awhile back, a customer of ours experiencing a similar issue, determined the noise was present on the ceiling grid and being induced into the speaker. This noise was constant, however and each time the ceiling speaker was lifted above the grid, the noise stopped. The customer ended up placing rubber or plastic tabs at each of the 4 corners to provide slight separation from the grid. Again, grasping at straws.
Definitely agree with other members here that have stated the noise is from an external source and not that of the paging system.
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Grasping at straws is better then pulling hair, any and all ideas are welcome.
I don't think its from the paging system either, its just coming over it.
Is the concept to get the metal frame of the speaker isolated from the metal grid ( I'm 95% sure there is no metal on metal contact )? Or are we just elevating the entire speaker above the grid, as in to brake a RF field?
Jason
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Let me take a stab at this. You say that you have disconnected the audio pair at each speaker leaving only the power and the noise persists. It's very possible that a noisy component in one of the speaker amps is putting noise on the common power wiring which in turn is picked up by the other speaker amps. The only way to find the one that is causing the problem is to disconnect each speaker completely first in groups then, when you have it narrowed down to a group, one by one.
And sorry Valcom, I know you make quality products that I have used many times but this problem illustrates one of the reasons why you should use a 70 volt system with this many speakers.
-Hal
CALIFORNIA PROPOSITION 65 WARNING: Some comments made by me are known to the State of California to cause irreversible brain damage and serious mental disorders leading to confinement.
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Lifting the speakers from the grid is to isolate vibrations not metal to metal. I had a wall speaker do this once caused from a bad bearing in a ventilation fan. The fan would vibrate the wall and the speaker cone would start vibrating causing a loud static like noise. I doubt this is the problem here but it may be worth a try.
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"Heating and cooling Zone controller ( Damper motors") Could it be possible that one of these motors is going bad electrically and either inducing noise that is being picked up by the breakroom speaker and transmitted to the rest or the noise is traveling along the power conductors of the motor back to the power source and breaker panel and finding its way to the speakers along its power leads?
Forty six years and still fascinated with Telecommunications!
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Mr Valcom, What is the difference between the bull horn and the ceiling speaker amps?
Jason
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Nothing. With the ceiling speakers you see it mounted to the speaker frame, it has the power and audio inputs on it's board. With the horn it's inside the driver housing at the back of the speaker. Whatever you are thinking that ain't it.
-Hal
CALIFORNIA PROPOSITION 65 WARNING: Some comments made by me are known to the State of California to cause irreversible brain damage and serious mental disorders leading to confinement.
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I ask to try to figure out why the noise is over the ceiling speakers but never the bull horns. Swapping power supplies or zone outputs, never changes. Just don't here the noise on bull horns. Therefor beside the obvious cosmetic look, whats different?
Jason
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Therefor beside the obvious cosmetic look, whats different?
The difference is that the horns are on a different power supply than the ceiling speakers! Read what I said above in my first post about noise on the power wiring generated by a noisy speaker amp and investigate that!
If you can't get anywhere with this and the problem is causing problems instead of just being annoying, consider removing the speakers and replacing them with standard 70 volt ceiling speakers and horns. You will need to use three PA amps or a single multi-channel unit, each channel input or amp input can supplied by the zone audio outputs of the Valcom 2003A maintaining your zone paging functionality.
-Hal
CALIFORNIA PROPOSITION 65 WARNING: Some comments made by me are known to the State of California to cause irreversible brain damage and serious mental disorders leading to confinement.
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"ceiling speakers mounted to the speaker frame, power and audio inputs on it's board. Horn it's inside the driver housing at the back of the speaker" Your ceiling speakers amps are external and stray voltage could be influenced onto them possibly by a difference in ground potential. The bull horn amps are protected by the housing which is at ground potenial.
Forty six years and still fascinated with Telecommunications!
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The bull horn amps are protected by the housing which is at ground potenial.
The horns are PLASTIC.
-Hal
CALIFORNIA PROPOSITION 65 WARNING: Some comments made by me are known to the State of California to cause irreversible brain damage and serious mental disorders leading to confinement.
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Check grounding and make sure there are no poor loose or corroded connections. With an ohm meter check for a difference in ground potential between the speaker grounds and building ground.
Forty six years and still fascinated with Telecommunications!
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There are no speaker grounds!
Come on guys!
-Hal
CALIFORNIA PROPOSITION 65 WARNING: Some comments made by me are known to the State of California to cause irreversible brain damage and serious mental disorders leading to confinement.
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hbiss, please my first post. Power supplies have been changed reconfigured and ALL speakers have been powered off of just 1 power supply. Bull horns still do not make the noise while ceiling speakers do from the same power supply. Power supply is not a issue. If I cant find the source, I would like to isolate it if possible. Therefor comparing a noisy speaker to a quite one, I'm attempting to find the differences.
Jason
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It's hard to believe that RF may be the cause of this but still possible. Even though the horns are plastic it is possible that they have some shielding around the amp. It also possible that there is a cap or resistor difference in the amplifiers that could make one react to a RF frequency while the other works fine. If a ceiling speaker and horn have both the audio and power connected in parallel and it only effects the speaker then that eliminates many components. Have you tried to shield the ceiling speaker amp?
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If I understand correctly the noise affects all the ceiling speakers not just one. The only practical way to shield these speakers is to install them in a back can connected to a proper ground. If it were me and it came down to that I would rather rip it all out and do it the right way. Self powered speakers all over the place with power and line level audio wiring (especially home run from each speaker) is not the way to go. You're only asking for trouble.
-Hal
CALIFORNIA PROPOSITION 65 WARNING: Some comments made by me are known to the State of California to cause irreversible brain damage and serious mental disorders leading to confinement.
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Suga Ray Jay,
Just wanted to know if you tracked down the source of the problem and corrected it ?
Thanks,
Forty six years and still fascinated with Telecommunications!
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Have not found the problem yet. This issue is more or less on the back burner now. I am looking into replacing the ceiling speakers though.
Jason
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I'm pulling my hair out with a somewhat similar problem... all my ceiling speakers have a low hum on them while they are idle, but none of the horns (using same power supplies) have any hum on them. I'm stumped.
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This thread is from 2012. Try starting a new one
Patrick T. Caezza Santa Paula, CA 93060 C-7 - Low Voltage System Contractor - Lic# 992448
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OS 7030
by Bushmills - 09/03/24 12:42 PM
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