Strange 6kHz noise in my new house, any ideas? (Update - getting closer)

Johan Allard

Power User
Hi guys,

Just wanted to see if anyone's have had anything similar issues and possible solutions?

We have renovated our house and moved back in just before Christmas. It's our forever home and we've done a lot of work to it. There's complete new wiring throughout, we've added solar panels and a Tesla Powerwall. As soon as I connected everything up in my office/music room I noticed quite a lot of different noises that I'm currently trying to track down.

The first and loudest noise was sort of a crackling noise in my studio monitors that happened as soon as I turn on the LED lights in the staircase. They are the only ones that are powered by a transformer. I have no idea so far if the noise is caused by the transformer or the lights themselves but today I added an USB isolator to my Audioengine DAC and that made that noise almost completely disappear. There's still a very, very slight noise when the LED stairlights are on but no where near as bad as before. I did try to add a ferrite bead after the transformer but that didn't do anything.

The other issue that I have no idea what's causing it at the moment is a high pitched noise whenever I play guitar (through my FM3). The noise is a constant 6kHz noise and happens when the guitar's volume is turned up. I can work around it by adding a peaking PEQ with -12dB, max Q and 6kHz frequency first in my chain. I have measured with an EMF (Electromagnetic Field meter) and there's hardly any EMF interference. It doesn't really matter which way I point my guitar or stand at different places, it's still there. I've turned off the lights, A/C, all computer related stuff, studio monitors, ... and play through the FM3 directly connected with one of my CLRs and it's still there, ruling out any electric interference from the computer stuff and the noise is still there.

Through my hours and hours worth of Internet searches I've understood that solar can lead to dirty electricity. I have ordered an EMI dirty electricity meter to help troubleshoot this. I got a Furman AC 210 power conditioner today and tried running everything through that and it made zero difference. I've contemplated getting a double online conversation UPS (where the UPS always uses the battery so should make a perfect sine wave a clean power) but these require a fan to operate so basically trading one type of noise for another. If that is indeed the best/only solution I could place the UPS in the cupboard next to the office/music room, cut a hole in the wall and run the power from there.

So, anyone have any similar experience with anything like this? Any experience using solar in a home studio environment? Is a double conversion UPS just a waste of money? Are there different/better power conditioners than the Furman that could potentially solve this? Or is there something else all together that could potentially fix this?

Thanks in advance for any ideas.
 
Maybe the noise is not coming in through your power cable but instead coming from the source wirelessly and is picked up by your music equipment. UPS will not help in that case. Try a good shielded guitar cable first.

Finding the source of the noise should be the priority, only then you should look for solution.

I suspect the LED driver.

Maybe try using your beaker panel to turn off the circuits one by one to narrow down the location of the noise source!
 
Thanks for the response.

I‘ve tried using different cables and using a wireless system. No difference. Also, usually when there’s some form of non-electrical interference it’s directional so moving around would change the amplitude of the issue. But in this case the 6kHz issue is there, at the same level, wherever I’m standing in the room or whatever direction I’m pointing with the guitar, leaning me to believe that it’s not a non-electrical issue. It could still definitely be something over the air but as far as my understanding about this stuff it would be directional from the source that sends the signal that gets picked up.

The 6kHz issue is there with no lights on in the house. I haven’t tried turning off the fridge or Internet related stuff yet (firewalls, switches, NAS, ...) but I’ve never had or heard of any issues with anything like that before, which is kind of why I’m suspecting the solar inverter.

I’m still waiting to get a run-down of exactly how the solar stuff is connected so not sure yet what I can turn off to try things related to that. But was hoping that someone here had any experience either with running their home studio in a house with solar panels and a battery.
 
Thanks for the response.

I‘ve tried using different cables and using a wireless system. No difference. Also, usually when there’s some form of non-electrical interference it’s directional so moving around would change the amplitude of the issue. But in this case the 6kHz issue is there, at the same level, wherever I’m standing in the room or whatever direction I’m pointing with the guitar, leaning me to believe that it’s not a non-electrical issue. It could still definitely be something over the air but as far as my understanding about this stuff it would be directional from the source that sends the signal that gets picked up.

The 6kHz issue is there with no lights on in the house. I haven’t tried turning off the fridge or Internet related stuff yet (firewalls, switches, NAS, ...) but I’ve never had or heard of any issues with anything like that before, which is kind of why I’m suspecting the solar inverter.

I’m still waiting to get a run-down of exactly how the solar stuff is connected so not sure yet what I can turn off to try things related to that. But was hoping that someone here had any experience either with running their home studio in a house with solar panels and a battery.
What is the switching frequency of your inverter?
 
An oscilloscope could be used to "look" at the power source voltage for your Studio Room. That would tell you if the 6 kHz noise signal in the power line.

If you have a breaker panel try cutting power one by one to all the circuits in your home. That would eliminate potential noise generating devices in those circuits.

If your noise is still there that may be pointing to as @jakel suggested to the solar inverter. Trying to help, but I have no knowledge in solar energy power systems!
 
Ask any electrical contractor company to check with a Fluke the THDI current distortion factor of your installation. No use to check THDU; voltage can be beautiful while your current waveform is a shit. 6kHz is a 2nd octave harmonic of 60Hz so no doubt that it's a bad filtered power converter somewhere. The best way to check is cut of all circuit breakers and test one by one with the fluke which one powers the source of your problem. Once identified, you might contact the supplier of the equipment for a solution; or change the converter for a decent one. Danfoss are amongst the best if you can have one where you live.
Edit : a solution means : add a filter to the converter. These can be quite expensive so it's good business for the supplier to 'forget' to insert that (standard) option on the converter
 
6kHz is a 2nd octave harmonic of 60Hz
Sorry no. The 2nd harmonic of 60Hz is 120Hz.

It still does sound like dirty power though.

I assume turning guitar volume down doesn't affect the noise, right? Does turning down the level of your monitors? Unplugging the inputs to them? Divide and conquer, as always in troubleshooting anything.

Sounds terribly frustrating.
 
Have you made sure it’s not the FM3? Try it in another room or house. Make sure it’s not the CLR. What about with headphones?
 
Id agree with posts above, turn off things in the house and isolate to strip diagnostics, get a fluke if you can afford it but they can get very expensive, I cant tell you how many times have been tricked by bad guitar pots, jack solder joints even very very expensive Monster cables that picked up noises and changed them out for moderately priced ones that fixed the issue. Do you hear the sound with the FM3 when no guitar is plugged in but your patch is engaged (not muted)? I've always made sure all of my gear is running through good AC power conditioners. finally I think I'd have the electrician isolate the music room on its own set of breakers. Good luck Im sure you'll get to the fix, I'll be following as Im interested in what it is...
 
Were the people who did the electrical system and its design aware of your audio requirements? Have you explained your problem to them? If so, what did they say and are they able to help?
 
Do you have any dimmer switches for your lights in the house? The ones that use pulse modulation (all but the > $100 per switch) are going to induce high frequency into the power line. Any power brick can also radiate HF noise.

Get a cheap AM radio and tune it to static. Aim it around the house to find the source.
 
Thanks for the responses guys, yes it's all terribly frustrating. Also, I'm in Australia so the base frequency would be 50Hz, not 60Hz, but I don't think any strong harmonies would take it to 6kHz.

At the moment, it's looking more and more likely that it's actually non-electrical. Which in a way is even more frustrating.

Todays test included getting a UPS (a standard cheapish APC one, not a double online converter one) and ran my FM3 and CLR off the battery from the UPS and the issue was still there. I've previously tested and the issue is present both in my Adams A5x's and the CLR so don't think it's related to the monitors as such. And to exclude the FM3 I plugged the guitar directly into the CLR running off the UPS, turned the volume up quite a bit to compensate for having no preamp, and while the issue was muted, it was still very much there. I then grabbed my backup, a Tech 21 FlyRig and the issue was there with that one as well.

And sure, the power coming off the APC UPS on battery is probably some form of squarish wave instead of a pristine sine wave, but could it be exactly the same squarish inverter off the UPS that gives the exact same issue as when running off the mains? Maybe I'll order a double online UPS anyway, just to rule that out.

Next step in testing was giving the guitar to my wife and carry the FlyRig and CLR to 4 different points of the house (upstairs/downstairs, far east/west), plugged into the mains and the issue was there in all locations. We could find quieter spots pointing the guitar into the wall at a few different places, but almost everywhere there was that distinct 6kHz noise.

One other thing that we did manage to notice was that when holding the guitar right up to one of the dimmers, and I mean pickups 10cm (4inch) from the switch, we could hear additional noise as well but it wasn't the 6kHz noise, it was a different noise at a lower frequency. But yes, there's dimmers in pretty much every room so maybe the dimmers is what's causing the issue.

What I've done to manage to hide it, is to add a PEQ block in the beginning of my chain. And from testing today, I think that 5.9kHz is a better block than 6kHz. At -12dB it's still very much audible, at -24dB still but at -36dB it's silent. At least to my 50 year old ears :)

Screen Shot 2021-01-12 at 6.41.02 pm.png

Tomorrow, I'll see if I can cut all the light switches out on the mains power board and see if that makes a difference. The troubleshooting continues...
 
It could be coming from outside the house. A transformer on a pole, a smart-meter on the side of the house...
 
Thanks for the responses guys, yes it's all terribly frustrating. Also, I'm in Australia so the base frequency would be 50Hz, not 60Hz, but I don't think any strong harmonies would take it to 6kHz.

At the moment, it's looking more and more likely that it's actually non-electrical. Which in a way is even more frustrating.

Todays test included getting a UPS (a standard cheapish APC one, not a double online converter one) and ran my FM3 and CLR off the battery from the UPS and the issue was still there. I've previously tested and the issue is present both in my Adams A5x's and the CLR so don't think it's related to the monitors as such. And to exclude the FM3 I plugged the guitar directly into the CLR running off the UPS, turned the volume up quite a bit to compensate for having no preamp, and while the issue was muted, it was still very much there. I then grabbed my backup, a Tech 21 FlyRig and the issue was there with that one as well.

And sure, the power coming off the APC UPS on battery is probably some form of squarish wave instead of a pristine sine wave, but could it be exactly the same squarish inverter off the UPS that gives the exact same issue as when running off the mains? Maybe I'll order a double online UPS anyway, just to rule that out.

Next step in testing was giving the guitar to my wife and carry the FlyRig and CLR to 4 different points of the house (upstairs/downstairs, far east/west), plugged into the mains and the issue was there in all locations. We could find quieter spots pointing the guitar into the wall at a few different places, but almost everywhere there was that distinct 6kHz noise.

One other thing that we did manage to notice was that when holding the guitar right up to one of the dimmers, and I mean pickups 10cm (4inch) from the switch, we could hear additional noise as well but it wasn't the 6kHz noise, it was a different noise at a lower frequency. But yes, there's dimmers in pretty much every room so maybe the dimmers is what's causing the issue.

What I've done to manage to hide it, is to add a PEQ block in the beginning of my chain. And from testing today, I think that 5.9kHz is a better block than 6kHz. At -12dB it's still very much audible, at -24dB still but at -36dB it's silent. At least to my 50 year old ears :)

View attachment 77298

Tomorrow, I'll see if I can cut all the light switches out on the mains power board and see if that makes a difference. The troubleshooting continues...
I suggest :

1- Turn off all the electrical breakers in the electrical and the solar panels system (including the power wall) and redo the same test you did (i.e. running your setup from the UPS battery).

That should give you an idea if it’s noise coming from one of these items. Although the power wall may still be running so you may have to actually shut it off if that is possible. Or wait until the batteries run out.

You then can turn back on one breaker at a time and see (hear!) which system cause the issue.

All this assuming it comes from the house. If it doesn’t, I would move to the next step which would be try the setup away from the house. In a car for example since you can run the setup from the UPS battery.
 
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Sorry no. The 2nd harmonic of 60Hz is 120Hz.

It still does sound like dirty power though.

I assume turning guitar volume down doesn't affect the noise, right? Does turning down the level of your monitors? Unplugging the inputs to them? Divide and conquer, as always in troubleshooting anything.

Sounds terribly frustrating.
2nd OCTAVE harmonic (ie on a logarithmic scale..). As it's 50Hz base frequency it's a 3rd Octave harmonic, 120th to be precise, which means it's probably not a "harmonic" ( 120th would be very much, as well as a 100th harmonic BTW). But could be a cutting frequency of the DC-AC inverter from your solar system. Maybe chexj the documentation and/or verify if the supplier brand does propose any harmonic filter solutions/options for this equipment.
 
2nd OCTAVE harmonic (ie on a logarithmic scale..). As it's 50Hz base frequency it's a 3rd Octave harmonic, 120th to be precise

This still doesn't make sense. Going up one octave means doubling the frequency. The 120th harmonic is almost 7 octaves (~83 semitones) above the fundamental frequency. You seem to be mixing up Hz and harmonic numbers.
 
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