What on earth is this noise?

Renoized · 03-04-2021, 10:36 AM

So my guitar picks up some weird sounds in addition to the typical 50 cycle hum. Here's an example:

https://www.dropbox.com/s/nk8sjw4cn8...Noise.wav?dl=0

The beginning is the 50 cycle hum without a noise gate, annoying enough but manageable. Can anyone tell me what the noise in the middle is and the possible solutions? It comes seemingly at random at a frequency of 1350Hz. Could have none for an hour then a few per minute, I can't work it out. I've even heard it at work from the flourescent lights there. I'm in Cologne, Germany, if that helps.

I've been troubleshooting this for years, it even followed me when I moved house. Different guitars, cables, amps, audio interfaces, you name it. I'm pulling my hair out with it. I'm even running through a DI box, I thought that might be a long shot, but might fix it, nope.

Hopefully someone knows!
Alex

Bribedant · 03-04-2021, 11:30 AM

Yea well, I had my share of noise hunting too. Got rid of all LED lamps in my studio. That helped the continuous bzzz. Your problem, does it always comes in burst's of the same length as in the audio file?

Renoized · 03-04-2021, 12:25 PM

Quote:

Originally Posted by Bribedant

does it always comes in burst's of the same length as in the audio file?

Not always, they can be longer or shorter, but not by very much, only a few seconds. Bursts is a good way of describing them.

Funicello3 · 03-04-2021, 12:40 PM

It sounds like radio interference to me. Is there some wireless device nearby that could be causing it?

Jimmy James · 03-04-2021, 01:09 PM

Grab a wireless remove control for a TV. Turn on your guitar and recording rig. Then point the remote control at your pickup and hold down a button. Are the sounds similar?

Allybye · 03-04-2021, 02:24 PM

I agree that is sounds like rf interference probably detected in equipment as modulation reflected into the audio band (like radio demodulation) or perhaps aliasing once picked up.

Not looked at it's spectrum but it sounds like two distinct frequencies such as frequency modulation of a binary but regular signal.

Against that it seems too regular (within the burst!) so it could also be some equipment oscillating intermittently. That can happen for example in a power supply with some regulators and poor design.

However seems odd that it is location and equipment independent (all equipment changed?).

As you have experienced, with intermittent interference of the type you experienced, to find the cause can be difficult.
If there are no obvious sources in the building and you have different equipment that does point to an extetnal cause (such as a powerful transmitter) a welder or other indudtrial equipment or something of your own you have not considered. It can be a process of elimination switching off equipment till everything has been eliminated before considering extetnal causes. Sometimes it can be something as simple as an switching of a crude type of thermostat (heater, fridge) starters on flourescent lights etc. It seems unlimely f the frequency is always identical as they can be more broadband sources.

Could be down to a process of eliminition and keeping a diary of events to get some more clues!

Sorry, not much to go on!

Renoized · 03-04-2021, 03:22 PM

Quote:

Originally Posted by Allybye

However seems odd that it is location and equipment independent (all equipment changed?).

Very. New soundcard, new guitar (old one had active, now passive), new amp sim, regardless of cables etc. The computer is the same, I suppose, but I don't think that's the cause. I'm on Wifi and that doesn't seem to be causing any issues. (That's 2.4 or 5kHz anyway)

Quote:

Originally Posted by Allybye

Not looked at it's spectrum but it sounds like two distinct frequencies such as frequency modulation of a binary but regular signal.

You know what? You're exactly right! I looked again and there appears to be a second signal at 4kHz. No idea what that could be...

Quote:

Originally Posted by Jimmy James

Grab a wireless remove control for a TV. Turn on your guitar and recording rig. Then point the remote control at your pickup and hold down a button. Are the sounds similar?

I'm afraid we don't have a TV or a radio to check with! It may well be radio interference but I honestly don't know what it could be. I'll see about borrowing one from someone...

As a troubleshooting attempt, I've unplugged the printer. It's got a wireless function but it connects to my computer via cable. I doubt that's it, but we'll see.

Thanks for the input folks!

Renoized · 03-04-2021, 03:45 PM

Still happening, not the printer. -_-

karbomusic · 03-04-2021, 04:22 PM

Unlikely by the sound but cell phone?

Renoized · 03-05-2021, 06:56 AM

Quote:

Originally Posted by karbomusic

Unlikely by the sound but cell phone?

I've tried it and it's a very different noise from the phone.

bolgwrad · 03-05-2021, 04:18 PM

First thing that occurred to me was 'dial-up modem initializing'. May be a clue, may not.

Barafu Albino Cheetah · 03-05-2021, 04:25 PM

Are you near the airport?

WarrenG · 03-05-2021, 04:30 PM

Refrigerator cycling?

W

karbomusic · 03-05-2021, 04:34 PM

Aliens?

WarrenG · 03-05-2021, 04:44 PM

you got those too?

A 60's experience?

Bribedant · 03-06-2021, 04:46 PM

Quote:

Originally Posted by Barafu Albino Cheetah

Are you near the airport?

yea, that's what I was thinking too. Civil or military air strip with radar. Doubt it but who knows. Had a under ground rehearsal studio neighbor to a radio amateur ages ago. That did not work well. He could hear the kick drum thru 50 m of rock, we could hear his radio transmissions thru every amp.

Tubeguy · 03-07-2021, 01:38 AM

I get similar noises when I plug in an extra EQ or some preamp in to my recording setup. For me it's a ground loop problem. Goes away when I unplug what ever I normally don't have in the system. Sometimes I have to run the signal through isolation transformer to break the ground loop.

Renoized · 03-07-2021, 04:44 AM

Quote:

Originally Posted by Barafu Albino Cheetah

Are you near the airport?

Nowhere near the airport! I'm in the city centre. Radio might be an idea though, not sure where. I live in a residential street.

Quote:

Originally Posted by Tubeguy

I get similar noises when I plug in an extra EQ or some preamp in to my recording setup. For me it's a ground loop problem. Goes away when I unplug what ever I normally don't have in the system. Sometimes I have to run the signal through isolation transformer to break the ground loop.

This only happens for me with guitar, and this recording has come through a DI box already.

Reason · 03-08-2021, 08:53 AM

Is there any other equipment in the house that has stayed the same, eg a microwave oven? If you've changed houses, guitars, cables, amps, and recording methods, that's where I'd look.

Renoized · 04-02-2021, 04:17 PM

I'm a step closer! It appears to be something about Cologne, the "ripple control signal" the thing that the power station uses to control day and night power or something? They send a modulated frequency along the power lines, doesn't normally cause an issue, only by high end audio equipment and dimmer switches!

https://en.wikipedia.org/wiki/Load_management

Now I just need to find a way to filter it out...

Bribedant · 04-02-2021, 05:15 PM

Quote:

Originally Posted by Renoized

I'm a step closer! It appears to be something about Cologne, the "ripple control signal" the thing that the power station uses to control day and night power or something? They send a modulated frequency along the power lines, doesn't normally cause an issue, only by high end audio equipment and dimmer switches!

https://en.wikipedia.org/wiki/Load_management

Now I just need to find a way to filter it out...

Interesting. So it's dirty power maybe. The hifi/home movie AV guys and medical machines tech's knows about this and how to fix. Not very cheap tho I guess.

Edit. Had to google EMI filter for "homes" and found that it's not really that expensive. A pizza and a beer money...

Allybye · 04-03-2021, 03:17 AM

Two things (at least) you need to address.

Firstly is how the control signal on your power is getting picked up.
Maybe more likely that it is via the power supplied directly into equipment. In that case it should be possible to filter it out.

Could also be getting picked up via ground loops or by equipment on the signal input sides when it has been radiated by electromagnetic sources such as cabling.

Filtering is often the easiest way to deal with both cauuses (as well as eliminating ground loops!).

The former can be done on the power inputs at or into to the equipment. It is best if that is part of equipment design.

The latter closer to the power source gives woder protection but that will probably require filters of greater power rating. The supply to ring mains is a good place to install them but that then requires electrical work that you may need an electrician to do that for you.

Could well be a trial and error method starting at the equipment end. Much easier to do with add on filter units.

Two things to bear in mind:

For mains power with RCCD trips (leakage detection for safety) that are now common a balanced filter is required i.e. filters that work on both live and neutral connections so that there is not an inbalance at switch on causing unwanted niusance tripping.

Secondly the vast majority of filters for EMI/RFI are designed for high frequency elimination upwards of several kHz or MHz. You need ones for much lower frequencies -effective filtering at your known frequency.

One easy route might be through an uninterruptible (though battery) power supply that has inbuilt filtering.

Renoized · 04-16-2021, 03:09 PM

I wasn't really expecting any replies!

Quote:

Originally Posted by Bribedant

Interesting. So it's dirty power maybe. The hifi/home movie AV guys and medical machines tech's knows about this and how to fix. Not very cheap tho I guess.

Edit. Had to google EMI filter for "homes" and found that it's not really that expensive. A pizza and a beer money...

Can you share a link? I'm still pulling up nothing.

Bribedant · 04-16-2021, 05:55 PM

Quote:

Originally Posted by Renoized

I wasn't really expecting any replies!
Can you share a link? I'm still pulling up nothing.

Living in sweden I get swedish search results but try
EMI filter for power supply
Noise Suppressor Power EMI Filter
searches.

Allybye · 04-17-2021, 03:01 AM

I reiterate my recent post especially
"Secondly the vast majority of filters for EMI/RFI are designed for high frequency elimination upwards of several kHz or MHz. You need ones for much lower frequencies -effective filtering at your known frequency.

One easy route might be through an uninterruptible (though battery) power supply that has inbuilt filtering. "

Most off the shelf emi/rfi filters do not filter to "low" frequencies such as 1350Hz (low in terms of the overall electromagnetic spectrum rather than audio spectrum).

Don't take my word for it read https://www.google.com/url?q=https:/...nU5L1YVUApVqFP

-centre column just under the heading!

Will not do any harm but unlikely to cure your problem!

EDIT: Thinking about the problem again , my first port of call would be the low voltage (230v ) supply company/organisation.If they generate the interference it could well be that they are not meeting the standards that they should comply with and they ought to rectify the problem at source or at least when where it enters your property!

Bribedant · 04-17-2021, 05:16 PM

Hm, true that. But couldn't there be a hi frequency carrier signal resulting in audible noise? My own experience is of amateur radio interference in a rehearsal studio. Unbearable, we had to make d.i.y filter on every amp input. But that was radio and topic is of power line. A different ballgame I guess.

Allybye · 04-18-2021, 04:47 AM

"Hm, true that. But couldn't there be a hi frequency carrier signal resulting in audible noise? "

Hmmm, also true. It could be a much higher frequency demodulated, detected or aliased into that audio spectrum. Nothing wrong with what you write.

However the OP has established that the frequency is local power company control signal. I am of course presuming that it is travelling along the supply wires at the 1350Hz quoted and heard. But as filters that you mention are cheap to try and can reduce other sources of interference too so maybe worth trying?

I do not have information how the power control signal is communicated, could well be r.f carrier modulated and not via the live wires too. Bad solder joints do have a habit of detecting rf signals and acting like diodes resulting in the base band modulation! With high impedance circuits (like old valve amps and guitar interfaces with unbalanced signals) these can be quite good a picking up radio like the old medium wave AM transmissions that I had trouble with in my early teens!!