2. analog
  3. 127317-5312

Periodic noise

My system picks up noise every eight minutes. There is a kind of scratching mid-register ("ta-ra-ta-ta") sound that last for ten or fifteen seconds. It is similar to descriptions of "GSM buzz" but it happens regularly and regardless of whether our mobile phones are on or off. It happens when the analog source is selected, not other sources (or not obvious, in my system). It is very clear when the volume is mid-high, with no music playing. It is not from the cartridge and the tonearm cable, since it happens even when I disconnect them from the phono stage. When I disconnect the phono stage, however, I don't hear it. So it seems to be picked up from the phono stage itself. It happens across different phono stages. Shielding the cables with ferrite does not help much. It seems like a very strong signal.

Anyone recognizes this problem?
o_holter
lewm
13,667 posts
 
One approach to figuring this out would be first to determine whether the noise is getting into your system via the AC line or via the air.  If you have or can borrow an AC regenerator or some sort of very good AC filter, see if that makes any difference.  (Of course, RF is often so high in frequency that it gets by any sort of commonly used filter, but it's worth a try.)

Perhaps also you can fashion some sort of Faraday cage and place it over your phono stage, in hopes of blocking airborne interference.
gdnrbob
4,497 posts
 
I recall a post where someone realized that a neon sign downstairs was causing the periodic noise. YMMV.
Bob
totem395
390 posts
 
The time interval between occurrence being every 8 or so minuets 
has me scratching my head.

almarg's avatar
almarg
9,670 posts
 
Could be a nearby security system device, such as this one, which is described as transmitting various information every 8 minutes.

Good luck.  Regards,
-- Al

mattmiller's avatar
mattmiller
1,547 posts
 
Are you using any Wall wart devices to extend the range of your router and adds a CAT 5 to the wall? Unplug them! while listening to music. I doubt seriously that it is your phono pre amp. Also, make sure everything is plugged into a cheap power strip except the amp plug that into the wall and listen to your system then. Sometimes having a lot of cords going to different outlets can cause noise, popping. It really sounds like a ground problem.

Matt M
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