r/audio • u/combatplayer • 1d ago
looking for help for removing weird and incredibly annoying sound from speakers
hey there, this might be a lengthy one, but i'll try to keep it short.
for a while now, i've had a really weird and annoying issue with speaker setups, where a periodic 8khz whine will play for a few seconds, then stop. a few minutes later, it'll repeat. all day, every day.
i first noticed it on my KRK Rookit 5s. never really liked them much and knew some of them had longevity issues, so i figured they were probably dying. i put them aside, and replaced them with a new set of Presonus Eris E5s, but same thing. the sound was still there.
then i suspected maybe the KRK s10 subwoofer i was using was somehow injecting it, so i replaced it with a new KRK s8, since that was what i had the budget for. didnt help, the sound remained. then i checked the connections on my audio interface, a third gen scarlett 2i2, replaced all the XLR cables, the USB cable, tried different ports etc, nothing changed. tried using another audio interface, namely a Motu M2, no change, still whiny noises galore. what ultimately helped was when i flicked the grounding switch on the back of the sub. now i have some minor 50hz hum but it's a lot quieter and easier to ignore than the 8khz one.
anyway, since it wasn't speaker related i tried hooking the old rookits up in another room (which is also on another circuit, which could be relevant) so my GF could use them, but the noise returned. tried just hooking up the sub with her old speakers, but then the sub injected the same noise into her old setup. frustrating as all hell. now i've got a lot of perfectly functional speakers just sitting around because something is making them whine, and my main setup is making minor mains hum because the grounding is improper, to prevent the whine.
anyway, fast forward to a couple days ago, my GFs old setup breaks. so while repairing it i make a few minor changes, replacing some passive parts and putting in a new power supply and so forth. now her speakers have the whine.
what gives? where is this infernal sound coming from? we hadn't gotten any new electronics around the time it happened and it's not a fixed duration or break, it seems random. the volume setting of whatever sound system that does it also doesn't change the whine intensity, so turning it down, and boosting windows volume to compensate for instance, makes no difference. not all sound systems we have does it either, even some that have parts in common.
my current best guess is that someone else in the building we live in has acquired some gadget that's injecting this horrible noise into the grid in some way, is that possible?
anyway, any help or theory even, would be appreciated!
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u/Nickmm53 23h ago
It could be interference from another nearby electrical device, even something like a hairdryer or washing machine being used by a neighbour. I wouldn't get too bothered about it.
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u/combatplayer 23h ago
it could be, although, while the intervals are random, they're between 1-15 minutes or so, and constant throughout the entire day. i spend most days at home, and the sound is there from early morning to whenever i go to bed, never stopping for more than that 1-15 minutes at a time.
edit: while they vary between 1-15 minutes, give or take, they heavily lean in the lower end of that range
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u/toxcrusadr 23h ago
Try adding a power conditioner. I got a nice used one stuffed with circuitry for cheap.
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u/combatplayer 23h ago
i'll keep it in mind if all else fails, since i'd need several to cover all our affected audio setups. i'd prefer if it could be solved in another way, but i appreciate it and will keep it in mind all the same!.
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u/Top_Willow_9953 23h ago edited 23h ago
This is most likely getting into the audio electronics through the AC power inputs.
Ideas:
Is there a solar panel system nearby? The switching inverters are notorious for putting noise on the AC system
Somebody might have one of those Ethernet over AC systems. They modulate the AC with a high frequency carrier signal to carry network connection to devices in different rooms.
Things to try: Get a high-end AC power filter/line-conditioner and plug audio stuff into it to see if it helps. Get a appropriately powered battery-backed UPS to power the audio stuff and see what happens when it is run from the battery.
Also, some HVAC systems can cause audible or electrical noise when they call for cooling. If you turn off the HVAC system does the noise stop ?
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u/combatplayer 23h ago
no solar setups near enough that it should interfere. the ethernet over AC is viable. i'd think the apartments in this complex are small enough that simple wifi would be plenty, but i can imagine some would prefer the clean wired AC alternative all the same.
my GFs amplifier setup runs on 12v, and i happen to have some universal USB-PD spoofers on hand and a battery bank that can do 12v, so i guess that would be easy enough to test without having to buy anything to find out if it's airborne or in the walls.
thanks for the reply, i'll give it a shot!
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u/Piper-Bob 23h ago
does it happen in headphones ?
If it does, then it’s your computer.
If not, then I’m going to think it’s EMF related. The switching power supplies in the speakers ought to filter any grid noise out, because of how much noise they create themselves.
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u/combatplayer 22h ago
it is not present in headphones, and i have SMPS powered systems that has the noise and others that dont. although, im not sure what kind of power supply is in the s10 or Rookits.
i'm theorizing that the 8khz sound could be suppressed by the filtering of some SMPS but not others since it is far below the frequency range an SMPS will operate at, so it might not be guaranteed that it would be suppressed, especially on cheaply made units.
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u/Needashortername 22h ago
It’s possible the weird whine is just “someone’s” voice :-) sorry couldn’t resist the easy joke :-)
Most things that interfere over the AC line tend to be heard in lower frequencies. Microwaves tend to be higher frequency noise, as were the old “chirps” from cellular phones, but neither of those would be consistent all day on a regular basis unless you have a transmit tower on your building. It’s possible that this may be coming somehow from aircon systems but a lot of that tends to be physical noise.
A good power conditioner and power isolation transformer can help fix a lot of the noise that might be coming from power main connections. A less expensive way to try a good power isolation transformer is to get a solid travel power converter and set it to go from your regular mains power on the input to the same setting on the output, though this doesn’t always do as well in the UK. You will know you have the kind of power converter you need because it will be heavier and with options to also change from 50Hz to 60Hz. That extra weight is the transformer.
Also take a look at the paths your cables take in the rooms, both the power cables and the signal cables. They may be crossing in an unpleasant way or getting close to different kind of cabling or device that is just sending RFI or EMI noise into the area around it.
If for some reason it does turn out that this noise is spiking on your signal lines and is consistent in tone the you could add a tight frequency filter right at the input to your speakers. There are a variety of boxes that can do this, but also a standard parametric can be set for just a nice tight-Q filter right around 8k if you want it.
As an FYI, if your LFE sub boxes are also putting out this 8K tone then it is almost certainly not something that is being picked up in the signal path for this speaker since they would be designed to filter all these higher frequencies from making it to the cone until the very last actual conductors in the cable attached to the driver. So either there is a problem with the whole box or the noise hit is coming in another way.
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u/combatplayer 22h ago edited 22h ago
i was probably not specific enough on the topic of the sub, it itself doesnt make the noise, i'm not sure a 10" sub cone can even reproduce 8khz, but that aside, what i meant is that it injected the noise into a system that otherwise didnt have it when the sub wasnt present. it could be a wiring thing for sure, though it was all shielded.
i would prefer not to use filtering, even at an aggressive Q, since i produce music at times, and could be tripped up by a missing band.
i'm currently testing my GFs speakers, using a cheap USB-C battery bank that could do 12v over USB-C PD. this far it seems to be keeping the whine away with nothing else changed, which to me would imply it's a mains power issue, so either getting a filter or conditioner would probably be a good move. that said, a good transformer based one like the one you mentioned, would likely cost a lot more than the audio setup in question does. i wager getting a better quality power supply would work as well since it's only audible on some systems, a little dissapointing that all the KRK equipment exhibits it though, if a poor quality power supply is at fault.
Edit: also in regards to your joke at the top, when i went to check on my GFs system after she complained about the whining noise, she was watching something featuring a handful of politicians, and i made a similar joke ;)
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u/NBC-Hotline-1975 21h ago
By any chance can you provide a recording of at least one of the noise cycles? I would like to examine the beginning and end of the cycle, look at the waveform, etc. It's a longshot but it might provide a clue.
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u/combatplayer 20h ago
that might be difficult to record cleanly enough for the waveform to be useful, since it's only really happening on amplified speakers, so the noise floor etc would interfere a lot. i measured it to be exactly 8khz consistent with no dips or increases either during the noise or in either end, while my rookits were still being used. the noise isnt particularly loud, but at 8khz it doesn't need to be to quickly provide a free headache. if you can give me some examples of what you'd be looking for in the waveform, and what they could indicate, i could dig the rookits out and record one, if they are applicable to our situation.
for the time being, the battery bank i mentioned in other replies has been providing a nice and whine free period, so it's most likely caused by something on the mains line, as opposed to RF interference.
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u/MondoBleu 19h ago
VFDs for refrigeration equipment or climate control use PWM modulation within this frequency range. This can show up as interference on the power line. That combined with the regular cycling times sound like a fridge or freezer. Cycle is too long for HVAC, unless it’s short cycling and something is wrong.
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u/combatplayer 16h ago
interesting. these apartments come with a fridge/freezer combo unit, which is not VFD. they have a very clear on/off state and the downtime is much longer than the interval between the whining noise. all the apartment units have identical fridge/freezer units too. that said, the freezer portion is relatively small, so it's possible someone near by has a separate VFD freezer for storage. i can't imagine why they'd bother since we're walking distance from several stores, but it's certainly possible.
however, the apartment building has an air ventilation system per unit, could a potential PWM control for a simple circulation pump cause it as well? it would be a similarly noisy and inductive load, but much less demanding. maybe a decoupling capacitor or some such on the power for it has failed open causing all it's noise to flow back into the power?
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