My poweramp has evolved to a receiver!
Posted by: Wito on 24 February 2003
Since a couple of months my NAP 250 has been picking up and sending radiowaves to my speakers. Quite loud sometimes.
It all began approx two months after we moved to our new house. One night a heard radio coming out from my speakers. After disconnecting anything but the 250, the speakercables, NAC A5, and the speakers i have located the source to the poweramp. By rearranging the speakercables i can increase or decrease the volume.
I have borrowed i friends poweramp, 110, and the radio disappears.
I have moved the stereo around in our house without any success.
I have mounted a separate fuse and mains cable from the house electrical central.
I have found out that its FM 103,3 Mhz.
Sometimes when we are watching TV in the same room it sounds like there is a radio on in another room. Its quite annoying.
Has anyone experienced something similar?
Tomas
Posted on: 24 February 2003 by Dev B
Tomas,
Sounds like your amp needs to go back to the Naim doctor. NAim used to do a RF kit for the poweramps in extreme situations, but the advice used to be to make sure the amp is working as it should (i.e nothing is wrong with it) and experiment with the location and make sure contacts and connections are clean and well made.
regards
Dev
Posted on: 24 February 2003 by mathew farley
Hi wito, I've had exactly the same problem its only happened to me twice. My hi-fi is in my bedroom at the moment, and it has woke me up a couple of times, The first time i heard voices, the second time was just a deep rumbling noise. I've been meaning to post but forgot about it. Also i get funny buzzing noises coming from my amp(180) but i only notice it at night, and it only lasts a few seconds (I assumed it was mains noise)
Posted on: 25 February 2003 by NaimDropper
This has got to be some sort of AM signal, it is not possible for a regular power amplifier (even a Naim!) to demodulate frequency modulated information. The detection you are experiencing is that of the "cat whisker diode" radio you (or your parents) made as a kid. One of the semiconductor junctions in your amp is acting like a diode (well, they all do in a way!) and received interference from an AM carrier is being detected (demodulated) and getting into the downstream stages of the amplifier.
I would call your local radio station and tell them you are getting such interference. They may want to know as they could be unintentionally transmitting it or there could be a problem with their equipment.
Try relocating your amplifier and see if the problem remains.
You may want to try some screening with large, grounded metal sheets (try aluminum foil first). Experiment with positioning and see if it helps. Be careful not to contact any live plugs to avoid the dangers of electrical shock!!!
Also, carefully check the grounding on your kit and in your house. If it is not completely intact, you are more susceptable to this type of interference.
Good luck,
David
Posted on: 25 February 2003 by Wito
Thanks Dev, Mathew and NaimDropper for your reply.
I've tried to moving my amplifier around without any success. Aluminum foil didnt make any difference either.
What made a difference, at first, was when i shifted to a shorter loudspeakercable, from 6 meters down to four. Both NAC A5. The amp was silent for a couple of weeks but now its all the same again.
I've talked to Terracom, who are responsable for the broadcasting in Sweden, but they deny any responsibility what so ever.
Tomas
Posted on: 26 February 2003 by minime
same problem year's ago every sunday afternoon french radio out of 1 speaker i had a ion amp rega 2 t/table the nearer the arm got to the spindle the louder it got. across the back a guy had a sat dish installed it was pointing straight at my hi fi gear i moved it out of line, prob solved.
