I just upgraded my amp from a NAP 180 Olive to a NAP 250 Olive and I frequently get a local radio station coming through my speakers since then. I have added a PS Audio power conditions, which reduced the problem but has not elimintated it.
I tried wrappingthe cables between my NAIT 102 and the NAP with Faraday pouch cloth and even experimented with wrapping the whole NAP 250 in Faraday cloth with no improvement. My system is on a dedicated electrical circuit.
Any suggestion to eliminate the radio station noise are appreciated!
It’s a reasonably common issue. The speaker cable acts like an antenna and forms a fully circuit back to the source and the end result can be picking up radio.
It can be misleading because it goes away if you disconnect the source, or preamp making one suspect they might be the issue but that’s just because you’ve broken the circuit. The speaker cables arrangement is almost certainly the culprit.
Try arranging your speaker cables differently and ensure the slack is not stored under the rack in proximity to the power amp. Both the 250 and 135s were known to be particularly prone to this.
I did play with re-arranging the speaker cables but I will try again. I will also try wrapping them in Faraday cloth or copper mesh of the right size for the frequency of the station I am hearing.
Thanks!
Wow, OK, no wonder! FWIW, In such situations Burndy cables can be really problematic , but speaker cables are the usual culprits. When it gets really bad, it can even prevent operation of a the unit. Do you run the cables all together? If so, try spreading them out as best you can. You might also try some ferrites.
The system is to the right of the right channel, so the speaker cables have different runs. However, the cable for the right channel is currently looped because I’m trying to follow the Naim guidelines for speaker cable length. I’ll move the cables around to see if I can make a difference. Thanks!
While that may help it doesn’t actually help prove the 250 has an actual fault. Because this problem has been know to occur with certain Naim power amps, moreso 250 and 135s than others. A different power amp based on a different circuit design is almost certainly going to cause the issue to go away but won’t really root cause it.
I remember picking up radio so loud I could hear it in the next room through the wall even when the volume was all the way down. The speaker cable zig zagged under the rack with the 250 on the bottom shelf was the issue in my situation. Changing from zig zag under the amp to large loose coil behind the speakers resolved it.
IIRC the NAP250 can be especially prone to picking up RFI if it’s not absolutely spot-on - Robin tried to explain it to me many years ago, something to do with oscillation of a particular component or components. That may explain why it’s not such an issue with your NAP180. @NeilS may know more on this. Otherwise I’ll try and find something from my old notes.
I expect Robin meant the 10uF caps on the output of the power supplies, these are the ones responsible for the “frying bacon” noises when a service is overdue. As this amp was serviced ~2 years ago, I wouldn’t think they’d be the culprets.
Well worth removing the loops in the speaker cable (temporarily) & see if it helps.