web statisticsweb stats Business Phone Systems Tech Talk Forum - VOIP & Cloud Phone Help

Business Phone Systems

Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
#482562 08/25/11 01:18 PM
Joined: Mar 2008
Posts: 166
Member
OP Offline
Member
Joined: Mar 2008
Posts: 166
I recently took on a new job at a school district. On the intercom systems where Valcom is installed, the original installers installed paging in the hallways of the schools using amplifiers wired for 25 volts. Why would anyone do this. I was thinking 7o volts was the normal. The paging sounds muffled at all locations. Also, they used the Aux input of the amp, instead of the telephone input for the Valcom system.

At 1 particular location, they installed a paging amp for one Zone, and self amplified speakers for another zone. I get a call today, and they reported that the zone the amp is on is bleeding onto the zone the self amplified speakers are on, causing the self amplified speakers to be broadcasting outside the school when the page was meant for inside.
When I looked at this I figured you shouldn't mix
self amplified speakers with speakers driven by an amplifier, or this could cause bleed over.

Am I correct, or am I missing something? Also, could the fact that all inside paging only speakers being on a 25 volt system and the amp connect to the aux port cause the muffle sound?


Gerald Ducote
NWA Telcom
[email protected]
Atcom VoIP Phones
VoIP Demo

Best VoIP Phones Canada


Visit Atcom to get started with your new business VoIP phone system ASAP
Turn up is quick, painless, and can often be done same day.
Let us show you how to do VoIP right, resulting in crystal clear call quality and easy-to-use features that make everyone happy!
Proudly serving Canada from coast to coast.

#482563 08/25/11 01:37 PM
Joined: Dec 2002
Posts: 9,423
Likes: 1
Member
*****
Offline
Member
*****
Joined: Dec 2002
Posts: 9,423
Likes: 1
In some locales any wiring above 50 volts has to be in conduit, thus 25 volt gets around that requirement. You just tap the speakers differently on a 25 volt line.
I think most PA/intercom systems use 25 volts instead of 70.
Could be that the speakers are mis-tapped.


Jeff Moss

Moss Communications
Computer Repair-Networking-Cabling
MBSWWYPBX, JGAE
#482564 08/25/11 02:03 PM
Joined: Jan 2002
Posts: 2,328
Moderator-Comdial
*****
Offline
Moderator-Comdial
*****
Joined: Jan 2002
Posts: 2,328
Now after years of handyman workmanship and jury rigs a knowledgeable person steps into the position. I don't envy you your job!

#482565 08/25/11 02:05 PM
Joined: Sep 2005
Posts: 9,285
Likes: 6
Admin
*****
Offline
Admin
*****
Joined: Sep 2005
Posts: 9,285
Likes: 6
25 volt is normal for school intercom partly because of the low voltage requirements as Jeff said and also because they don't need much power to each speaker. 1/4-1/2 watt is normal
The muffled could be either the amp is overloaded or an impedance mismatch on the input. You can run both a regular amp and self powered from the same source but you need to isolate both conductors of the signal from each other system so not to have bleed over.


Merritt

Business Telephones & Equipment + Commercial Audio/Video Products
Commercial Communications . . . Turner, Maine
If it was built after 1980 don't expect it to work right.
#482566 08/25/11 03:12 PM
Joined: May 2007
Posts: 5,058
Likes: 5
Moderator-1A2, Cabling
*****
Offline
Moderator-1A2, Cabling
*****
Joined: May 2007
Posts: 5,058
Likes: 5
What Jeff & Merritt said.

You're going to have to troubleshoot this. Do you have an impedance meter? It'll let you look at a run of speakers and see if the run is overloaded. If not you'll have to start from basics:

Disco all the speakers.
Hook up one speaker to one zone. Is it muffled or clean?
Add more speakers. Keep adding till you find the problem.
Start on the second zone.
Add one speaker. Are you getting bleed-through?

DO THIS ON T&M!!!! IT'S GOING TO TAKE A WHILE.

Sam


"Where are we going and why are we in this hand basket?"
#482567 08/25/11 04:16 PM
Joined: Dec 2007
Posts: 908
Member
Offline
Member
Joined: Dec 2007
Posts: 908
Here in California 25volt is required for Schools.(don't want to shock the little bas*****).

#482568 08/25/11 11:20 PM
Joined: Jul 2006
Posts: 2,713
Likes: 10
Admin
***
Offline
Admin
***
Joined: Jul 2006
Posts: 2,713
Likes: 10
K-Mart's were notorious for using 25 volts. The bad news was those systems don't take to kindly to employees "adding a speaker". You can usually tell that because you can fry an egg on the amp. They just keep on turning up the volume while the amp works its heart out to compensate for the 8 ohm load across the speaker line.

The only mistake I made was learning the reason you don't put your Mic cable in the same run as the speaker line. Probably the same reason you don't put Valcom amplified speakers in the same run as your speaker lines.... Fortunately I only did it once :-)

Carl

#482569 08/26/11 09:23 AM
Joined: Dec 2005
Posts: 7,056
RIP Moderator-Mitel, Panasonic
*****
Offline
RIP Moderator-Mitel, Panasonic
*****
Joined: Dec 2005
Posts: 7,056
If all else fails, use a relay to short the Valcom speech path, or power down the Valcom 24 Volt power when they're supposed to be silent.

As for the muffled sound, you have either got an overloaded amplifier, 1 or more 4-16 ohm speakers without 25 volt transformers, one or more bad speakers, or a 'tired' amplifier. In any case, you'll want to do an eyes on inspection and test of each 25 volt speaker.

As SAM said, T & M ONLY!!!! And the Impedance Meter will save you HOURS, or even DAYS.

One more possibility. I have seen neophytes try to use the 25 volt line power to power Valcom speakers! NO, IT WON'T WORK. If you're lucky there won't be any damage.


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.
#482570 08/26/11 03:36 PM
Joined: Jan 2008
Posts: 3,821
Retired Moderator
****
Offline
Retired Moderator
****
Joined: Jan 2008
Posts: 3,821
The Valcom and 25 volt speakers can share a common audio source but cannot share a common power source. First I would make sure all the Valcoms are working correctly with one pair coming from the 24 volt power supply that is large enough to power the number of speakers you have. That is the biggest mistake that is made, a power supply that doesn't have enough units to power all the speakers. When connecting a 70 volt source to Valcom paging you should use PN v-1095. This single gang expansion module allows a Valcom system to be connected anywhere on 25/70/100 volt line without straining the the existing amp.


www.myrandomviews
"Old phone guys never die, they just get locked in some closet with an old phone system and forgotten about"

Retired, taking photographs and hoping to fly one of my many kites.
#482571 08/29/11 07:34 AM
Joined: Mar 2008
Posts: 166
Member
OP Offline
Member
Joined: Mar 2008
Posts: 166
Turns out the bleed over on the valcom self amplified speakers was caused by the background music option being turned on on the valcm intercom system, and no background music source installed. I turned it off, and no more bleed over.

Thanks for all your advice on troubleshooting, and 25 volt paging. I'm still working on the muffled problem.


Gerald Ducote
NWA Telcom
[email protected]
#482572 08/30/11 01:42 AM
Joined: May 2007
Posts: 5,058
Likes: 5
Moderator-1A2, Cabling
*****
Offline
Moderator-1A2, Cabling
*****
Joined: May 2007
Posts: 5,058
Likes: 5
Quote
Originally posted by NWA Telcom:
Turns out the bleed over on the valcom self amplified speakers was caused by the background music option being turned on on the valcm intercom system, and no background music source installed. I turned it off, and no more bleed over.
That's something I should have mentioned. Open inputs look for signal. If they don't have one of their own they'll hunt down someone else's.

Good catch. Keep working on the muffling. You'll get it.

Sam


"Where are we going and why are we in this hand basket?"
#482573 08/31/11 09:01 PM
Joined: Jun 2011
Posts: 82
Member
Offline
Member
Joined: Jun 2011
Posts: 82
Quote
Originally posted by Jim Baldwin:
Here in California 25volt is required for Schools.(don't want to shock the little bas*****).
Here in UK we just use 100V for audio mad

#482574 09/01/11 01:28 AM
Joined: May 2007
Posts: 5,058
Likes: 5
Moderator-1A2, Cabling
*****
Offline
Moderator-1A2, Cabling
*****
Joined: May 2007
Posts: 5,058
Likes: 5
Quote
Originally posted by Owain:
Quote
Originally posted by Jim Baldwin:
[b] Here in California 25volt is required for Schools.(don't want to shock the little bas*****).
Here in UK we just use 100V for audio mad [/b]
Yes, but you also use 240v for "standard" electrical service (which is much better then 120- but tthat's another thread).

I did a job for a British Company with offices here in NYC. The PA was spec'd by the home office and the equipment was 100V. Interestingly, the transformers had taps on them for 200V too!

Sam


"Where are we going and why are we in this hand basket?"
#482575 09/11/11 06:01 AM
Joined: Jun 2011
Posts: 82
Member
Offline
Member
Joined: Jun 2011
Posts: 82
Quote
Originally posted by Silversam:


I did a job for a British Company with offices here in NYC. The PA was spec'd by the home office and the equipment was 100V. Interestingly, the transformers had taps on them for 200V too!

Sam
I've never seen 200V used at the speakers but it's possible the 200V amp output was used for large installations such as Radio Butlins holiday camps, and there was a 200V-100V transformer closer to each speaker cluster or line of 'chalets'.

Hi-de-Hi!

#482576 09/20/11 01:38 AM
Joined: Sep 2011
Posts: 6
Member
Offline
Member
Joined: Sep 2011
Posts: 6
Quote
Originally posted by NWA Telcom:
I recently took on a new job at a school district. On the intercom systems where Valcom is installed, the original installers installed paging in the hallways of the schools using amplifiers wired for 25 volts. Why would anyone do this. I was thinking 7o volts was the normal. The paging sounds muffled at all locations. Also, they used the Aux input of the amp, instead of the telephone input for the Valcom system.

At 1 particular location, they installed a paging amp for one Zone, and self amplified speakers for another zone. I get a call today, and they reported that the zone the amp is on is bleeding onto the zone the self amplified speakers are on, causing the self amplified speakers to be broadcasting outside the school when the page was meant for inside.
When I looked at this I figured you shouldn't mix
self amplified speakers with speakers driven by an amplifier, or this could cause bleed over.

Am I correct, or am I missing something? Also, could the fact that all inside paging only speakers being on a 25 volt system and the amp connect to the aux port cause the muffle sound?

#482577 09/20/11 01:43 AM
Joined: Sep 2011
Posts: 6
Member
Offline
Member
Joined: Sep 2011
Posts: 6
I came across this site while trying to find someone that could help with my problem. I work for a K-12 school in Cincinnati. Six years ago we constructed a new building and had someone install a Valcom paging system. This was one of those (side jobs) by a cabling guy. Apparently he didn't know what he was doing because it has never worked properly. Every time it rains, the system does not work. It doesn't perform the "all call" function and any announcements made are filled with static. I have had a few companies come in and none have been able to identify the problem. I don't know what to do. We rely heavily on that system. Do any of you know of anyone in the greater Cincinnati area that knows how to work on a Valcom system? We do not have anyone on staff that understands the system. HELP!

#482578 10/04/11 11:07 AM
Joined: Jun 2011
Posts: 82
Member
Offline
Member
Joined: Jun 2011
Posts: 82
Quote
Originally posted by Renn:
Apparently he didn't know what he was doing because it has never worked properly. Every time it rains, the system does not work.
well, you've obviously got cabling faults and water ingress. Go right back to the start and sketch out a diagram of every piece of equipment and length of cable. Disconnect every piece of equipment; test amplifiers etc on the test bench, test speakers in situ with a local (battery powered) test amp.

Megger every length of cable core-core and core-earth for insulation faults, shorts and open circuits.

Then reinstall the workinbg equipments in sections, working to the manufacturer's instructions, testing as you go.
https://www.valcom.com/techsupport/knowledge.htm

#482579 10/04/11 02:01 PM
Joined: Dec 2002
Posts: 9,423
Likes: 1
Member
*****
Offline
Member
*****
Joined: Dec 2002
Posts: 9,423
Likes: 1
Renn, PM sent.


Jeff Moss

Moss Communications
Computer Repair-Networking-Cabling
MBSWWYPBX, JGAE
Page 1 of 2 1 2

Moderated by  metelcom 

Link Copied to Clipboard
Forum Statistics
Forums84
Topics94,262
Posts638,694
Members49,757
Most Online5,661
May 23rd, 2018
Popular Topics(Views)
211,098 Shoretel
187,703 CTX100 install
186,794 1a2 system
Newest Members
BPopilek, Rich F, LewisR, TDKs79, Buttinset
49,757 Registered Users
Top Posters(30 Days)
dexman 18
Toner 14
TDKs79 8
pvj 4
Who's Online Now
2 members (teleco, BobRobert), 108 guests, and 249 robots.
Key: Admin, Global Mod, Mod
Contact Us | Sponsored by Atcom: One of the best VoIP Phone Canada Suppliers for your business telephone system!| Terms of Service

Sundance Communications is not affiliated with any of the above manufacturers. Sundance Phone System Forums - VOIP & Cloud Phone Help
©Copyright Sundance Communications 1998-2024
Powered by UBB.threads™ PHP Forum Software 7.7.5