🎓 Dr. Freemo 🇳🇱 @freemo@social.cleverlibre.org

Anyone except robbie and kamala :)

@snowgaze For sure :)

@snowgaze This one was unusually vibrant.. I dont quite see them with such a deep red color (largely because red doesnt show well in oceans)... It was amazing to see.

@thor Let me know how it goes... start with anything close by and move out.. if you get desperate you can power it off a battery source. Or move the speakers around and see what rooms it is loudest in.

@thor If it has poor shielding that would make the problem much much worse, but you still have RFI from somewhere, and its clearly some form of square wave, either an arc or a switching supply or other PWM type signal somewhere.

@thor So i just did some quick checking. the reason amps tend to show noise at 4khz is because they are tuned to have a peak frequency response right around there (which makes sense as that is where the audio frequencies are).

Due to the harmonics id still lean towards a switching powr supply.. the only other thing that would produce those sorts of harmonics would be an arc.

So if its not a switching supply in your home, and i presume you dont have high voltage in your home, then the next most likely culprit would be your power line transformer outside... it probably leaked its mineral oil and is internally arcing (very common and would produce this particular RFI)

@thor ITs very possible its a switching supply that isnt the amps supply itself... if its physically close enoough

@thor They dont generally develop over time. Switching power supplies are known to be noisy. They tend to be at higher frequencies though, but 4khz, while low, seems to be the norm in guitar amps for some reason I cant fathom.

@thor I'd be willing to bet its the powersource. Your speakers are likely using a switching power supply running at 4 khz.. the reason is a few 1) thats typical for guitar amps 2) the harmonics are typical of a square wave, which means your seeing RFI from a PWM like in a switching power supply.

So my top guess right now with like 80% certainty is that it is the power supply to the amp (if its a wall wart its that, if its a straight plug its internal).

@thor Perhaps so but 4 KHZ noise is well known to be common in guitar amps.

That said the source isnt the amp itself but oftent he wall wart... but 4 khz is very characteristic noise for a guitar amp for some reason.

Does the noise continue if only the power is hooked up but no audio in? can you try a different power source?

@thor Wait is this a guitar amp? and with a guitar hooked up?

@thor The volume of the hum is the same regardless of the volume nob? .. hmm thats unlikely to be RFI then

could be the power supply for the system, or a ground loop. If it is coming from outside the speaker it is traveling throught he power line then not the audio lines. RFI wouldnt be powerful enough usually to do much throught here which is what makes me think its a ground-loop issue or internal to the speakers.

Would require some more info to really narrow it down.. anyway if you need help let me know.

@thor No its either RFI or ground-loop issues. If you could get me a waterfall on that sound your hearing I can almost certainly tell you the likely source.

@thor Want my help as an EE?

One of the photos from my many dives int he #Maldives

#SCUBA #OCEAN