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Need help with Ground loop Humm
Posted: Fri Apr 12, 2019 10:34 am
by y2kindyz
Hello guys,
I hope this may have an easy fix. We had a VOIP telephone system installed at out business back in Oct. and for paging, we have a dedicated phone whose speaker output is sent to the AUX input of a small amp to send PA out to the yard. After they installed it, there was a noticeable humm when the Paging was not being used. As soon as a page would come thru voice is clear as a bell. I spoke to tech support over the past few months and tires to install a magnet around the speaker wire going to the amp and no change. Today O decided to give it a go again and I noticed that when I removed the network cable from the phone the humm sent away. So that lead me to my question since the network router and the amp are in 2 separate parts of the building, what can be done to correct the situation?
Any and all help is appreciated,
Thanks in advance,
Oscar
Re: Need help with Ground loop Humm
Posted: Fri Apr 12, 2019 11:47 am
by J_Dunavin
I assume if you pull the aux cable from the amp the noise goes away? Would an isolation transformer work in line there?
L/com also sells a network isolation box, ( see part number LC-60601-1) it’s not cheap, but a combination of the network isolator and the audio transformer may be the ticket.
Re: Need help with Ground loop Humm
Posted: Fri Apr 12, 2019 12:10 pm
by y2kindyz
Thank you for the response J_Dun. Yes when the aux cable is off no noise. Wow you were not kidding about them not being cheap. WOW shocked me at close to $300. Know I know what to for I will try and find a more cost effective solution. If not I may have to bite the bullet.
Thanks again
PS
That is why I love this forum.
Re: Need help with Ground loop Humm
Posted: Fri Apr 12, 2019 1:12 pm
by Bill Fitzmaurice
Causes and cures for ground loops:
http://www.rane.com/note110.html
Re: Need help with Ground loop Humm
Posted: Fri Apr 12, 2019 4:18 pm
by CoronaOperator
Re: Need help with Ground loop Humm
Posted: Mon Apr 15, 2019 12:55 pm
by madmallard
y2kindyz wrote: ↑Fri Apr 12, 2019 10:34 am
Hello guys,
I hope this may have an easy fix. We had a VOIP telephone system installed at out business back in Oct. and for paging, we have a dedicated phone whose speaker output is sent to the AUX input of a small amp to send PA out to the yard. After they installed it, there was a noticeable humm when the Paging was not being used. As soon as a page would come thru voice is clear as a bell. I spoke to tech support over the past few months and tires to install a magnet around the speaker wire going to the amp and no change. Today O decided to give it a go again and I noticed that when I removed the network cable from the phone the humm sent away. So that lead me to my question since the network router and the amp are in 2 separate parts of the building, what can be done to correct the situation?
Any and all help is appreciated,
Thanks in advance,
Oscar
first question. When the phone device is off/not carrying a call, its emitting a hum, but when its got an open voice line its not?
second, is the phone device powered off of the network cable run, or does it have its own power plug?
third, is this an output jack on the phone, or did someone literally open it up and wire the speakerphone terminals to a cable to run to the amp?
Re: Need help with Ground loop Humm
Posted: Fri Aug 02, 2019 9:54 pm
by y2kindyz
Sorry for the late reply. I have not had time to log on to site in a while. 1 I have not tried to remove power from phone and see if humm persist. 2 Phone has its own power plug. 3 Phone was opened up and speaker wires are being used as output to the amp. Phone does not have output jack. Still living with humm.
