[StarMatt]

Hello. I don't know a lot in that kind of things so I'll try to be clear:
I recently got for my birthday a pair of Tannoy Reveal Active which I try to connect to my computer on my Xonar Xense soundcard. To do so, I use a Y cable with 2 jacks 6.5 that I plug in the monitors, and a jack 3.5 that I plug in the soundcard. Unfortunately, when I turn the monitors on I hear a distinct high pitch noise (not an acousting feedback).
My question is simple: what could produce that kind of interference? And what can I do to resolve the problem?
It does not do the same thing when I connect the monitors to my phone or mp3 player for instance, so I don't think it comes from the cable.
I did some research on the web, and it could be a problem with the electricity (and I think this is the most likely scenario, but then again I don't know a big deal) and the way things are plugged: my computer and the monitors are plugged to a power strip. I tried to plug the computer to an outlet on the wall and the monitors on other outlets, but it didn't change anything. I also found that something like that might help (don't know the name in english) and fix the interference in case of an electricity issue.
A friend of mine who knows a lot more than me in that field told me it could also be simply because of the setup, and that I shouldn't connect the monitors via a mini-jack, but I think it's the only way I can connect them to the Xonar Xense.
 
Please, if you don't quite understand what I said, ask me to clarify things (which is likely since english isn't my native language), don't leave me hanging!
 
Thanks a lot everyone!

 

[PleasantSounds]

I'm not really familiar with the Xense model so I had to look it up - and I don't see a 3.5mm socket on it. Are you plugging it into the extender?
Try using the the 6.3mm headphone socket on the Xonar instead - that should work fine.

 

[StarMatt]

Hi, thanks for the answer.
The Xonar Xense comes with that. That's how you connect speakers to it. I already tried to plug them to the headphone socket but it does the same thing.

 

[StarMatt]

Some more information:
 
When I use the GPU (in games mostly), the noise is way louder! However, I tried removing the GPU but there is still interference in the monitors.
 
Could it be the PSU? I got a Fortron Hexa 500, maybe I need something better?
 
Also, when I plug the monitors to my MP3 player, there is no interference, but if I plug connect the player to the computer via USB, I can here interference. 
 
Well, so, I think it either comes from the PSU, or maybe because of the way I plugged everything to the electricity... Or could it also be the computer case? I got a Bitfenix Merc, maybe I need something better. I also didn't isolate the mobo from the case with insulators for instance (mainly because it didn't come with the case or the mobo), is that of any importance?
 
Thanks for you attention!

 

[PleasantSounds]

Here's a few things yu can try:
 
1. Does your motherboard have sound support? If so, try removing the soundcard and checking if the noise is there as well.
 
2. Plug in something else in place of your speakers (i.e. headphone amp, AV receiver) and see if the noise is still there.
 
3. Bypass the Windows sound mixer - use a player with ASIO or WASAPI (I'm assuming you're on Windows platform).

 

[StarMatt]

1/ Tried that already, there is still interference
2/ No problem with my headphones or my old 2.1 speakers
3/ Noise still there with ASIO

 

[stv014]

Do your new speakers have a grounded (3 prong) AC connector ? Your problem is most likely caused by a ground loop.
 

 

[PleasantSounds]

Looks like it could be a ground loop. 
Try powering your monitors with the earth plug disconnected - i.e. use a plug with only 2 bolts.

 

[StarMatt]

That might be complicated, I don't think I have a "non-earth plug" in my room. Is there a way to disconnect it? Again, I don't have a lot of outlets and I plug everything to a power strip.

 

[StarMatt]

Hm, when I plug the monitors to my netbook, which is plugged into an earth plug, there is no intereference. Is that relevent?
 
 
 

Do your new speakers have a grounded (3 prong) AC connector ?

 Yes.

 

[PleasantSounds]

You can get a small powerboard and a new plug, cut off the original one from the power board and wire it yourself leaving the earth prong not connected.
If the powerboard is serviceable (i.e. can be opened) you can just cut the earth wire in it. Just make sure it's unplugged when you do that

 

[Snag1e]

Sounds like a ground loop to me too... you can buy three to two prong cheater plugs very cheaply online that will likely fix it.

 

[StarMatt]

Cool. Will do. Or die trying at least.
Random question: isn't it dangerous to have my computer plugged into a non-earth plug?

 

[PleasantSounds]

Quote:

Cool. Will do. Or die trying at least.
Random question: isn't it dangerous to have my computer plugged into a non-earth plug?

 
I'd rather connect the monitors that way.
Cheers,

 

[StarMatt]

So the monitors but not the computer if I understand correctly?
Thanks for your help btw This forum is awesome.