Getting rid of 3.5mm hmmm

[ItsSoQuiet]

Using 3.5mm 7.1 into a yamaha 6090, yamaha 5740. There is a noise, or hmmm at higher levels (starting at -20 on amps). This noise is there with the Xonar sound card, and the onboard gigabyte 7.1. The noise is there with my other amd oem pc .

With the amd, even if the power cable is unhooked, nothing else connected to the pc but the 3.5mm cables, the noise is still there. I suspest the 6700k pc (in specs, the one I care about) would do the same.

This noise is obviously not there with sdif or hdmi.

What is interesting is that I have a Dell 8700 i7 with 7.1 analog and there is absolutely no noise using 3.5mm cables. I have another dell i5 with 7.1, and no hmmm or noise using analong cables.

The difference is definitely the computers, the dell computers are silent. Also, I connected a zune, and my Note3 to the amp, and no noise. I have the i5 connected in another house with 3.5mm and a yamaha 6080 amp, and no noise.

Any help appreciated

 

[FordGT90Concept]

3.5mm is usually analog stereo. If you use a digital connection (like SPDIF or HDMI), there won't be a hum. Usually interference comes from something not properly grounded in the case.

Please be more specific: What 3.5mm are you talking about? Rear or front? If you unplug the cable connecting the front to the motherboard, does the hum go away? Is the hum affected by touching metal on the case?

If you're trying to diagnose an analog hum on 3.5mm plugs, it is best to use 3.5mm headphones because they have no separate power circuitry nor amplification.

 

[thesmokingman]

Wait so you have tested multiple pc's in that setup and they both make noise? Ground loop? Get a ferrite core and loop the 3.5mm cables around it as a start or get a GL isolator.

 

[ItsSoQuiet]

Yea, 2 of the four pc's make noise. The 2 dell's I have tested make no noise. I have tested in 2 different houses, with 3 different yamaha amps. The noise is not a harsh noise, just a hmmm.

I have looked into those filters, will try those. I thought maybe it was something with the power supplies. Would be nice to figure what the difference is with the dell
.

 

[ItsSoQuiet]

I have a bunch of cables with those cores right before the connectors. Can I just monkey these on there somehow? I have psu cables, dvi, vga, etc. Some are bigger than other. Should I put them on both ends?

 

[thesmokingman]

I have a bunch of cables with those cores right before the connectors. Can I just monkey these on there somehow? I have psu cables, dvi, vga, etc. Some are bigger than other. Should I put them on both ends?

If they came with the cable they're probably not removable. I wouldn't mess with it since you can buy a pack of 20 ferrite cores for not much money. If you look around on amazon you will find many varieties, size, shape, etc to choose from.

https://www.amazon.com/dp/B00V4MMIBW/?tag=tec06d-20

 

[ItsSoQuiet]

I already removed a pair from a set of bad vga cables. Took about 10 seconds with a pair of box cutters.

They are just long bushings.

I am going to chop them in half, and heat shrink them onto the cables with some hot glue chips.

 

[eidairaman1]

Certain 3.5 cables are cheap and are not shielded properly, i have a coiled 3.5 here that makes my audio equipment hum if there is no music playing, i switched it out and no hum.

 

[ItsSoQuiet]

I have swapped cables, and still there. Do you have a link to the cables you have?

When you mean coiled, you mean the actual coils that stretch out make a difference?