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Silly tread
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SiliconWizard:
Just listened to your sound sample. (Yes the recording is very low volume, so we need to crank up the volume to actually hear anything.)

To me, it sounds like noise coupled from some switching power supply. Could be something like a computer monitor, or maybe LED lighting, or a lot of other possible sources. It's very possible it's coupled to the guitar pickups or its internal wiring as I suggested.

It could also be coupled to the guitar amp itself. You could try plugging in a jack with something like a 10k resistor to the amp's input, crank up its volume and see if you hear the same noise.

You could try and locate the noise source itself (by switching off any surrounding device one by one) until the noise disappears.

ebastler:

--- Quote from: 001 on November 28, 2018, 07:22:07 pm ---
--- Quote from: tpowell1830 on November 28, 2018, 07:19:12 pm ---Have you measured this frequency, it sounds much higher than 1 khz.

--- End quote ---
I can`t do this since signal is  muddy and  squeak is masked by others :-// It include some HF harmonics too

--- End quote ---

I took a quiet section of the signal, which mainly has the high-pitched noise, and Fourier-transformed it via Audacity. The dominant tone is pretty exactly 5 kHz.

Edit: Found the level control in Audacity's spectrum plot and attached a clearer version of the spectrum...
ebastler:

--- Quote from: 001 on November 28, 2018, 07:25:47 pm ---
--- Quote from: floobydust on November 28, 2018, 07:20:08 pm ---
I use a battery-powered audio amp with a pick-up coil, or an AM radio and look for the noise source. Do a walk around and see what can be found.

--- End quote ---
Yea whistle is everywere  |O

--- End quote ---

Just to be very clear: Is the signal audible (at similar levels) when you use a battery-powered amp only, without any mains connections? That's very relevant, since it allows you to distinguish whether the noise is coupled via the power line or via radiated emissions.
Buriedcode:

--- Quote from: 001 on November 28, 2018, 06:36:30 pm ---It is same for different guitars and amps  :-//

--- End quote ---

So its most likely radiated EMI.  Just to rule out the cable - have you shorted the end of the cable?  Does the interference disappear?


--- Quote from: chris_leyson on November 28, 2018, 08:41:12 pm ---...Floobydust has the right idea. A pickup coil and a battery powered audio amp might offer a few clues, ..

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Well he already has a pickup (the guitar) and amp.  Does it change in amplitude depending on where the guitar is?  My guitar seems like a pretty directional pickup to me - I have to face the window to not pickup the noise from the large collection of power bricks I have plugged into a multiway.
001:

--- Quote from: ebastler on November 29, 2018, 06:41:24 am ---I took a quiet section of the signal, which mainly has the high-pitched noise, and Fourier-transformed it via Audacity. The dominant tone is pretty exactly 5 kHz.


--- End quote ---

Thanx! Awesome help  :-+ What about this 5kHz peak nature?
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