Recently DIY Computer Build has Major EMI Issues, Remedies??

[MidiMagic]

My worst hum elimination problem.

The owner of the stereo and I were trying to get rid of hum in his right speaker. No matter what we tried, it was still there.

Suddenly I noticed the hum was still there when the stereo was turned off.

Someone had hung an electric clock on the other side of the wall behind the right speaker.

 

[Tribby2001]

HDMI cables are susceptible to and generate noise. You have some homework to do. Read about ferrites and their different core types for different noise sources and how to install them. There are several different ferrite compositions each designed to suppress various bands of frequencies of source noise.

https://palomar-engineers.com/ferri...DTV-A-V-units-I-O-cables-12-filters-p74369093

 

[Frogmort]

When I put together my dual Ultimax 18" subs with my Behringer power amp, I got terrible hum from both sub cabinets. I tried making sure the subs were on the same power line, and then made sure they were not on the same power line, and many different combinations of connections, but I arrived at the same conclusion that you did.

After dozens of iterations of trying different things to fix the terrible 60Hz hum, I tried lifting the ground from the subwoofer amp, and then hooking that ground-wire from the subwoofer power supply directly to the turntable ground screw on the back of my AVR. That instantly fixed my hum problem completely. I can now turn it loud as hell, and crank the bass, and still put my ear up to the subs, and it's absolutely silent.

 

[Tribby2001]

When I put together my dual Ultimax 18" subs with my Behringer power amp, I got terrible hum from both sub cabinets. I tried making sure the subs were on the same power line, and then made sure they were not on the same power line, and many different combinations of connections, but I arrived at the same conclusion that you did.

After dozens of iterations of trying different things to fix the terrible 60Hz hum, I tried lifting the ground from the subwoofer amp, and then hooking that ground-wire from the subwoofer power supply directly to the turntable ground screw on the back of my AVR. That instantly fixed my hum problem completely. I can now turn it loud as hell, and crank the bass, and still put my ear up to the subs, and it's absolutely silent.

My Vandersteen sub has a banana style ground plug with instructions to connect it to the pre-amp's ground.

 

[jimfisheye]

Ground loops will not be cured even a little with ferrite beads, FYI. The loop puts a ground path on "higher ground" and the noise can't drain "down hill" anymore. So it jumps into the signal wires. Put as many beads on the thing as you please but the call is coming from inside the house!

Give the ground a proper path again and suddenly all the little capacitors in the circuit start pulling noise outagain as the circuit design is restored.

 

[Tribby2001]

Ground loops will not be cured even a little with ferrite beads, FYI. The loop puts a ground path on "higher ground" and the noise can't drain "down hill" anymore. So it jumps into the signal wires. Put as many beads on the thing as you please but the call is coming from inside the house!

Give the ground a proper path again and suddenly all the little capacitors in the circuit start pulling noise outagain as the circuit design is restored.

Yes, of course. Ground loops and EMI/RFI are two different issues. But if your neighbor installs an appliance that radiates noise the properly chosen ferrites installed on both the appliance and your device(s) will help. No amount of grounding short of a faraday cage will help in this case.

 

[godathunder]

My worst hum elimination problem.

The owner of the stereo and I were trying to get rid of hum in his right speaker. No matter what we tried, it was still there.

Suddenly I noticed the hum was still there when the stereo was turned off.

Someone had hung an electric clock on the other side of the wall behind the right speaker.

Mine was the evening I spent trying to track down a strange resonance that seemed to be affecting some bass notes but only intermittently. Spent an hour or so with a section of the track on repeat whist I moved ornaments, braced things against drywall, covered things with cushions etc

Eventually the cat woke up and stopped her gentle snoring

Never have managed to eliminate a very low level hum from my system. Thankfully its quiet enough that its not really noticable unless Im listening to something thats nearly silent at 4am

 

[mandrix]

A long time ago, to patch my pc and Creative DTS-610 in one room to my primary/house AVR in another room, I ran 50 ft of analog cables under the house to the AVR and I had a terrible hum. Eventually I bought a some devices intended for use in a car, having some caps the size of D cell batteries and put it inline with the cables and it cured the hum.
At one point I just finally went with a 50 ft toslink cable, which could have saved me previous headaches. I had somehow failed to remember the Creative device had both analog and toslink outputs. lol.