Amplifier causing interference with FM tuner

Discussion in 'Beginners and Audiophytes' started by john262, Apr 23, 2013.

  1. john262 Audiophyte

    Apr 23, 2013
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    Hi. This is my first post in this forum. I recently got a Cambridge Audio 651A integrated amp. I really like it. It drives my vintage ESS speakers just fine. I got this because I prefer two channel audio. It replaced an old Onkyo receiver that I moved to my bedroom. I have a bluray player, a satellite TV receiver, my computer's sound card and a Yamaha AM/FM receiver connected to it. I am planning to get a turntable too but haven't yet.

    But there is a problem. The amp seems to be putting out some kind of interference that causes problems with FM radio reception on the Yamaha tuner that I have connected to it. Especially on weaker FM stations there is a very irritating and noticeable background noise. It sounds sort of like a pulsing sound. I do not get the interference with the other components, only the receiver.

    I am using a good quality RCA cable to connect the tuner to the amp. Adjusting the dipole antenna that I am using doesn't help. I do not notice the interference on the AM band, only FM. Switching from stereo to mono reduces it slightly but it's still there.

    Now here's the thing. I can connect that same tuner to my old Onkyo receiver and I do not get that same interference. And if I take a portable radio, turn on the FM band and hold it near the 651A I get that same interference but when I move the radio a few feet away from the amp it goes away. So I think it's definitely coming from the amp.

    And for some reason after the amp has been on for a while, perhaps half an hour, the interference goes away. But if I turn the amp off for a few minutes then turn it back on the interference comes back.

    Does anyone have any suggestions about what I can do to fix this? The amp is under warranty so if this is a defect I can get it repaired by I hate to have to pack it up and ship it to a repair facility. I emailed Cambridge Audio support and they said I should try swapping out the connecting cable with another one and also try plugging the amp into a good surge protector. I swapped the cable and it didn't help and I am already using a surge protector. I emailed them back but haven't heard back yet.

    Thanks for you help.

    Last edited: Apr 23, 2013

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