I have a problem with my dj controller about humming and buzzing noise.

Probably not the controller or cables but the PC itself that is causing a ground loop hum. Sometimes it is the power block but mostly it is inside the PC itself. Using a Macbook Pro or Macbook Air there would be no issues at all with hum. Some PC’s cause hum others are OK. It’s a common issue which is why most DJ’s and musicians choose to use Macs. Other forum members will be able to point you to PC models that do or don’t hum.

A professional studio can have desktop computer but it would most likely be a Mac and they would output the sound through a dedicated external sound card via USB and then into the studio monitors. Does your controller (what is it?) have a sound card built in or are you using the PC’s sound card?

Maxy – get off your Mac soapbox. Lots of PCs in the music industry too, and they’re working just fine thank you.

Dexter – ground hums can generally be traced back to bad cables or bad power. If you’ve swapped out cables and still have it, then try plugging the mixer and the PC into different circuits and see if you still have the hum. Ground hums can be a real pain to track down, and even a bigger pain to fix. Bars frequently run into this trouble when someone plugs a fridge into the same circuit that part of the sound system runs off of.

My question is, what are you playing from your laptop that you need a 3.5mm cable to the mixer?

In any serious sound environment, using built-in sound cards is hardly ever a really good idea, especially when using flimsy connectors like 3.5mm which are great (well sort of) for headphones on mobile devices, but really have no place in your set up when you need to get sound from the PC out to the mixer.

The minimum I would do in such a case is get a good stereo (or dual stereo/quad channel depending on your need) external USB sound card with proper connectors, preferably balanced XlR or 6.3mm Jack and proper RCA for that short line out to a stereo line in on a small PA or DJ mixer.