Help! Humming/Radio Interference - Powered Speaker

[Syncretia]

I solved the problem. The answer as a DI Box (Behringer HD400 ).

This is the setup

PC (USB)->
Saffire USB 6 (Balanced Out) ->
DI Box (Unbalanced Out RCA) ->
Stereo/Headphones

But, I'm pretty convinced that this was not a ground looping problem. I'm convinced that this was because of a lack of grounding. I'm still sure that the interface itself is faulty because 3 internal sound cards don't have this problem, the M-Audio FTP doesn't have this problem, and the NI Audio 2 doesn't have this problem either.

BTW: I recommend getting a different card for DJ'ing etc. I bought the NI Audio 2 last night and it's perfect without the DI box. Any sound card that needs a DI box is shit.

[svensat]

I have an Audio 2 DJ and have this problem. Only when my laptop power is plugged in though. Does that mean I just have a faulty power adapter? My ground loop isolator doesn't solve the problem.

DJTT users, please advise.

[don358]

Hey guys this is my first DJ set up so I need some help on what to do with my sound. I'm getting a significant loud "humming" noise AND to top it off I hear a loud radio host talking about politics... talk about buzz kill when I'm trying to mix

DJ Set-up Gear:

1. VCI-100 SE (Traktor Scratch Pro)
2. MBP 13
3. Saffire 6 USB External Audio
4. Technic RP-DJ1200a
5. [ame="http://www.amazon.com/Monster-PRO-800-Color-Coded-Performance/dp/B0002ZO5WC"]Amazon.com: Monster MP PRO 800 with Clean Power Stage 1, Surge Protection, and 8 Color-Coded Outlets High Performance Pro PowerCenter: Electronics@@AMEPARAM@@http://ecx.images-amazon.com/images/I/41BEDVt2bGL.@@AMEPARAM@@41BEDVt2bGL[/ame]
6. Two RCF ART-312As

*Note: All items were purchased new.

Location: On Campus Apartment

Overview:
So first I connected all the power plugs into the Monster Pro 800 (I purchased this after I went to Guitar Center and told them about my problem) Now I connected my VCI-100SE and Saffire 6 USB to my macbook pro via USB. Both are updated to it's most recent versions.
I connected the ART312a powered speakers from it's XLR to the Saffire 6's TRS 1&2 Outputs (the cables are 10 feet long btw) so I assumed the connection would be balanced thus no humming/interference coming from the speakers.

I am obviously wrong.

Now when I brought my gear to Guitar Center and just hooked up one of the speakers with the saffire 6 & mbp the speaker was pretty silent. A slight hum but it was fine.
I tried in different rooms of my apartment and I still get the same radio frequencies coming from the speakers along with the humming. I re-arranged my set up at different angles and made sure all my gear was physically close together but still no luck. Also the volume knob on the speakers have no effect on the loudness/quietness of the humming and radio. I have NO idea what I need to do and these are the only speakers I have to mix with at home lol.

So ANY "feedback" appreciated!

Here's what's happening:
You are located near an AM radio transmitter, and the wiring in your setup is acting as an antenna. The radio signal is "loud" enough to overdrive the input stage(s) of your equipment, causing them to act as AM detectors. You were probably out of this field at the Guitar Center, which is why there was no problem there.

In short, your speakers have inadequate RF filtering, like a lot of other equipment. I wonder if your microphones, etc. are also picking up the station. Maybe, you could listen to the output of your mixer with earphones, with the mic gains up all the way, to see if they are also picking up the station.

The "fix" should be simple and cheap: You need to install or have installed one or two resistors and capacitors to make a low-pass filter, which attenuates the incoming AM signal below the point where the input stages act as detectors. These filters need to be installed inside the amplified speakers. A simple RC filter with a cutoff of ~50 KHz should help a lot. Pls. reply if you would like details on installing such filter(s). I will need to ask you some questions.