There’s been an unfortunate development. Since 2 weeks or so both my Alesis M1’s produce a faint high pitched sine when they’re on. It’s not noise, it sounds like a pure sine (If I move around the room the interference pattern from the 2 speakers is very clear).
As far as I know nothing changed in my setup at that time.
I’ve done some troubleshooting and this is how far I got:
Disconnect signal cable: still there
Adjust gain knob: doesn’t change the sound
Disconnect all other devices on the same power outlet: still there
Move power connection to a grounded one on the same floor: still there
Move power connection to the living room: problem solved.
Conclusion: Something is up with the power in my room, but everything else in my room works just fine. I don’t know enough about speaker electronics to say more than that. Anyone have a clue what could cause this and more importantly: how I can solve it? I’m not willing to spend much cash on a power conditioner etc, for something that worked perfectly the last 5 years or so.
Perhaps nothing changed in your setup, but something may (must) have changed in your environment. Have you changed, added or replaced any lighting? Flourescent lights can cause this also their starters. Have you added any appliances on the same circuit? Are you in an apartment or a single detached house? If an apartment, perhaps a neighbour has installed something new. Also maybe try running a power extension cord from the living room to the room in question (temporarily of course) just to see if it’s really on the power line or perhaps an airborn interference.
So I let this rest for a while because I didn’t use my DAW much, but today I experimented with it again.
I used an extension lead to be able to walk around with my speaker. The noise is definitely coming from some kind of interference. In 1 location the tone could be very loud, 20cm further it would be nearly gone. It’s not related to the power, I put the extension leads in different sockets throughout the house, the noise only appears when the speaker is at the top floor.
I used a tuner app and apparently the tone is 1999.7Hz. I’m not sure what could cause a 2KHz interference and a quick google doesn’t reveal much. Additionally to the constant tone, there’s also some ‘digital sputtering’ sometimes, for lack of a better word. It sounds a bit like the sound a speaker can make when a phone is nearby. It’s not that though, I moved all my digital devices out of the way which had no effect.
I’m about to ask the neighbours if they changed something because I’m not sure where else to look.
Using Aluminum foil to cover just the left side of both speakers reduced the noise incredibly. It’s now faintly audible when listening for it, but I can work with this. Thanks for your suggestions though!
According to the specs (and the SOS review) they are shielded. Correct me if I’m wrong, but I believe magnetically shielding speakers isn’t to prevent interference, just to make sure you can safely use them alongside magnetically sensitive devices like CRT monitors and harddrives.
That is correct, but I understood it worked both ways.
In this case however, it’s probably a case of RF radiation which is a bit different.
It might disappear if the audio monitors could be further removed from the video screens.
If you put the foil on the rear side of the video screen does it achieve the same effect? It would look better if that worked as you would not see the foil in that case.
It doesn’t look like it’s the video monitor that’s causing the interference. Note that I currently covered the left side of both speakers (also the one left of the video monitor, so not between the speaker and video monitor) to get rid of the noise.
I’ve been experimenting with monitor placement, and even 4 meters away from their current position they pick up the noise. Interestingly enough there is a pattern when moving the speakers. Every 50cm or so, the whine will completely disappear. It’s hard to measure of course, but it seems like a perfect 3d sine distribution throughout the room.
At this point I’m just blaming the 4g tower across the street, I don’t know what else to blame.
