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.
Every eight minutes? And lasts for ten or fifteen seconds?
If you live in an urban setting or an apartment, discovering the source of this may be more difficult.
Look at any other wireless devices used around the house. In particular, those that may be close or too close to the hifi. A Wifi router could be one culprit. Another could be a device like a weather station remote or monitoring system that periodically connects to your network. (Or is your neighbors, looking to connect on your neighbors network.) Some GPS devices will have an interval like that to upload a changing position. Others, like those flat, white, locator tabs that help us find lost keys. Camera monitors, refrigerators, light switches, hot water heaters.
So much of life today is connected wireless. Do you have one of those new thermostats?
These things aren't supposed to interfere but many do. Sometimes the interfering noise may be a sign that the equipment may be starting to fail. Other devices are just plain nasty. I had a Sprint Blackberry model a few years ago that disrupted everything right before it rang.
Power off any othere dvices in the room you can. Routers, switches, thermostats (if WiFi enabled), cable TV, satellite receivers, etc as well as light switches, wall-wart chargers, anything at all that draws electricity.
See if this helps any.
Next, disconnect the phono stage from the AC outlet.
Fluorescent / high efficiency light bulbs, etc. can also contribute. Let us know.
Thanks! The noise is periodic and regular, every 8 minutes 30 seconds or so. Therefore, light bulbs, chargers, dimmers, thermostats etc are unlikely suspects. Turning off our wifi router, TVs and mobile phones etc is no help, the noise comes anyway. The noise sounds like wireless interference, it comes and goes a bit (but is not a radio station signal, more like a data packet burst).
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.
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.
Go to the electric panel and shut off each breaker one at a time. You might narrow it down using the process of elimination to what on that circuit is causing the problem!
Thanks for help! No neon signs nearby, no special equipment on, in our house. The noise is regular with 8 m 30 s intervals. It comes and goes a bit, and sounds like a wireless interference, much like standard mobile phone interference, except it is regular - rather than AC interference. We do have a security system in our house - I will check, could this be the cause.
You might want to check whether your main power board has a smart meter that monitors power usage and transmits power usage info back to supplier at regular intervals. Alternatively the source could be from neighbours, there are so many sources for wifi these days - routers, phones, many household appliances now have wifi active.
almarg - you were right. I unplugged the main alarm system control box and disconnected the battery. Now, the noise was gone. I will get service on the system tomorrow. It is both wired and wireless.
My wife signed us up for Verizon Fios. At one point, the Fios was going down with regularity, until I finally investigated our circuit breaker box, where they had installed an AC outlet to power their system, which is a simple plug-in. It was easy to demonstrate that power to the plug was intermittent, by simply wiggling the plug, causing our problem with lost service. When I opened the housing for the new AC outlet their tech had installed, I found that the wires were nearly floating free in the box, just barely in contact with the outlet, because of sloppy attention to detail. At least it was easy to fix. Then I noticed that the Verizon crew had tapped into my dedicated AC lines to power the new outlet they installed for Fios, thus assuring that my audio AC was constantly polluted with digital garbage. You've gotta keep an eye on these installers.
The solution so far - the installer moved the box out of the room with the stereo system, and up to the second floor of the house. Now the noise was gone. It comes from the GSM chip in the controller box (made by Honeywell) he told me.
I no longer hear the 8-minute bursts of noise, since the alarm control box is further away from the system. Now it is close to our bedrooms. And I wonder, how healthy is this, with such strong bursts? The installer did know about the problem, but they did not announce it (of course). When I asked for a better shielded control box he just looked at me. Then I asked, well, since the noise is produced by the wireless part of the box, can we have the alarm system wired, then? He answered: we don't do wired installations anymore.
Now it is close to our bedrooms. And I wonder, how healthy is this, with such strong bursts?
As can be seen in some past threads here, it is not uncommon for people to hear interference from radio stations when listening to phono sources. A factor in that, obviously, is the very high gains the signals at phono stage inputs are subjected to. In this case the issue arose only when the security device was in the same room as the phono stage, and only when that source was selected.
All of which would seem to suggest that the signal strength involved is very weak. And I suspect that it has to be, in order to meet FCC Class B certification requirements that are intended to protect against interference with radio and TV reception beyond distances of about 10 meters. And any potential for effects on health would presumably be further weakened in proportion to the low "duty cycle" (ten or fifteen seconds out of every 8 minutes). So personally I wouldn't be concerned.
It might be worthwhile, though, to try to find technical specs for the particular device via Google, or in the manual if you were given one. If an indication is provided of how much power it transmits, and at what frequency, it might be interesting to see how that compares with typical wifi power levels and frequencies. My understanding is that laptops may transmit a few tens of milliwatts in the 2.4 GHZ band, at a distance that is of course much closer to the user than the security device is likely to be. Also, I have a 2.4 GHZ wireless access point in my house which I understand to be considerably more powerful than most, and it can transmit up to a little under a watt when necessary.
Regards, -- Al
P.S: Cymbop, thank you kindly. However, I'd much rather listen to my stereo system than have to deal with all the problems the President has to face :-)
P.S: FWIW, I note the following statement in the datasheet for the security system device I linked to earlier, which like your device transmits every 8 minutes. This is in addition to a separate statement in the datasheet indicating compliance with FCC Part 15 requirements for a Class B digital device, which are intended to "provide reasonable protection against harmful interference in a residential installation."
Radio frequency radiation exposure information according 2.1091 / 2.1093 / OET bulletin 65 This equipment complies with FCC radiation exposure limits set forth for an uncontrolled environment. This equipment should be installed and operated with minimum distance of 20 cm between the radiator and your body. This transmitter must not be co-located or operating in conjunction with any other antenna or transmitter.
Thanks, Al. The transmitter was close to 8 METERS from the system, and yet the speakers made noise like mad. I am not in the "very worried about exposure" camp, but it was quite special. It is the pulse that matters (15-20 seconds per 8:20 minutes). If the specs only give the average radiation, they won't tell the full story. Thank you for your input, I will investigate some more.
The OP didn't say how long the interfering device had been in place or how long the interference (noise) had been perceptible.
So my question is: Could this noise be "a canary in a coal mine?"
In other words, if the devices had been in place for awhile but the noise only recently began to be heard, would it be an indication of something failing (a noise shunting capacitor perhaps?) in the signal chain?
Not that I want to turn over too many rocks but I am curious....
Good question, dbtom2, but I guess the answer is "no" since Mr. H stated in the OP that the issue occurred with multiple phono stages, and only when a phono stage was connected and selected.
If anyone is curious as to what led me to suggest the security system possibility, I have no particular knowledge of such things, and I don't have one in my house. What I did was to first Google one or two terms I thought might provide some clues, which turned out to not be helpful. I then Googled "every 8 minutes" (with the quotes) together with the word "signal." That led right to the security system device I linked to in my first post above, that is described as transmitting a signal every 8 minutes.
Yes, Al, your diagnosis was spot on. It illustrates the importance of describing the symptom precisely. It was only when I timed it, after just having been irritated by the burst of noise coming and going, that I started to make progress. I found that it was regularly periodic, like I described in the start of this thread. I got a lot of suggestions, and one of them hit the mark. Grateful to you all, and a happy new year.
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