DX3 Pro Hum issue

[solderdude]

Would be very easy to test for the OP.

A small piece of wire from under the screw of the rear panel touching the RCA out shield.
When the hum disappears the enclosure is not connected to signal ground.

 

[lystor]

Last three days my DX3 Pro is dead silent.
Nothing changed in my setup.
I hate this electrical magic.

 

[solderdude]

Well you probably did plug in and out the connectors and dragged it from here to there.
Possible that a connector made better contact or inside a connection made better contact or a wire is routed differently.

 

[gypsygib]

I have a similar problem. If I plug in both RCA cables I get an audible intermittent hum in the right earpiece on high gain. I think it may also be there on low gain but is much harder to hear. Nothing makes it go away

I've tested with just the DX3 connected to laptop on battery, still there. Tested with just the DX3 plugged into the wall and not connected to a computer and it's still there.

Only thing that gets rid of the intermittent hum is if I unplug the RCA cords or switch to lineout or dac mode. The RCA cables don't even need to be plugged into another device to produce the hum, they can be dangling out the back and the hum is still there on high gain. I've tired multiple cables and the stock PS and a Meanwell one and tested on a separate outlet in another room with nothing else plugged in. I'm starting to think the RCA ports weren't soldered properly but I don't know much about these things.

Also should add that the hum is present at any volume level and lower impedance headphones make it more noticeable.

 

[daftcombo]

Last three days my DX3 Pro is dead silent.
Nothing changed in my setup.
I hate this electrical magic.

I have a similar problem with a DJ-mixer. When I plug headphones in, sometimes there is a weird hum.
I live in a flat. I noticed that the hum only happens when my neighbours are at home (in the flat above). Probably when they have some light on or something. Maybe yours are on holiday?

I also have a lamp that can be turned on by touch. It doesn't work except when I also touch my radiator or anything metallic linked to the ground at the same time. (That's part of why I chose that avatar.)

If it happens again, try putting your DAC on your fridge or anything big & metallic...

 

[JLaFu]

Hello

My DX3 Pro has very silent but still noticeable hum in headphones (250 Ohm Beyerdynamic DT 1990 PRO) even with disconnected USB and TOSLINK cables.

The hum is constant and it does not change in frequency and intensity.
Hum does not depend on the volume level.

Hum disappears when I touch metal case of DX3 Pro with my finger.

Is it possible to eliminate this hum?

Europe, 230V / 50 Hz

Thank you

Hello, I have same issue.

Have you finally solved this problem?

With some BA earphones, I sometimes feel electrical spark on my ears. :<

 

[solderdude]

run a wire from the metal enclosure or RCA shield to a known ground. This could be water piping or central heating (with metal piping). Make sure to let the wire make contact with bare metal (not painted parts)
That should take care of any 'sparks' BUT could also make it worse when the sparks you get are from you being charged on a carpet or such.
In the latter case the problem is static electricity. In the former case it is earth leakage or poor grounding somewhere (PC connected to 2 prong mains socket for instance)

 

[ryohnosuke]

Hello

My DX3 Pro has very silent but still noticeable hum in headphones (250 Ohm Beyerdynamic DT 1990 PRO) even with disconnected USB and TOSLINK cables.

The hum is constant and it does not change in frequency and intensity.
Hum does not depend on the volume level.

Hum disappears when I touch metal case of DX3 Pro with my finger.

Is it possible to eliminate this hum?

Europe, 230V / 50 Hz

Thank you

I have exactly the same issue! I noticed it only happens if I touch the floor (with 'bare' feet) and USB is connected to my computer.

This building have not grounding system, could be that?