Please Help with possible Ground Loop problem.

[kyle g]

Hi DSF. I know there has been a few threads on ground loop before, but i've searched, including the google search but can't quite figure out the solution for my specific situation. I'll try explain my set up and what the problems are.

My setup:

PC running Traktor with Audio 8 via USB.
M Audio Delta 66 Soundcard for PC.
KRK Rokit 8 G2 monitors.
2 x 1210's and a DJM 600.

How i've got it set up:

I use this pc for both production and djing. Audio 8 is plugged in via USB supplied with the soundcard. My two 1210's are connected through the cables that are supplied with traktor. I have XLR out of my 'Master out' on my mixer, which go to a xlr-trs adaptor, so that i have 2 male TRS 1/4" to plug into my external 'break out box' for the delta 66. This is connected into my Inputs 1&2. From there I have 1/4" TRS from OUTPUTS 1&2 on the breakout box, 1 to each KRK monitor.
This allows me to have either my PC sound source playing, i.e itunes, and also my DJM-600 output.

My problems:

1. I have a soft high pitched humm and static kind of sound from my KRK's, this happens even when the computer is turned off. It is quite soft and not noticable when music is playing but i'd rather it not be there. Or is this normal?

2. When i plug my AUDIO 8 in via USB, i get a noticable static/white noise kind of sound through my monitors. This sound is constant and does not change with the volume of mixer or PC outputs. It is also present when the mixer is off. Though what i did notice is that if i unplug the cables from my 'Master out' on the DJM600 then this particular noise stops.

What I have done so far:

Bought 2 x ground loop isolators. I tried plugging it in both the line and phono inputs on my mixer (and obviously connecting the correct cables from audio . I thought this would have solved the problem as i had come to believe it was a ground loop problem. I feel like it is still a ground loop problem, since when i disconnect my mixer outputs, the noise is gone, so its something to do with the audio 8 being connected to the computer via the delta 66 breakout box.

Also i just purchased two male RCA to male XLR adaptors, and i plan use the 'monitor out' on my DJM600 rather than the 'master out', so i need RCA. And i was thinking of using one of the ground loop isolators in line with the 'monitor out'.

I hope this makes sense? And hopefully someone can shed some light on this for me because it's really fucking annoying!

Pce

[deadly_habit]

are you 1210s grounded?

[kyle g]

yeah one is internally grounded and the other is grounded via the mixer.

[nowaysj]

This sounds like some radio frequency/shielding problem. I've heard of this with the rokits, but have never experienced it (have to turn them way up and stick my ear on the tweeter to hear a hiss). I think all of the reports I've heard have been outside of the US, unless I'm mistaken. A ground hum will sound quite low, it'll be that, a low hum.

Also way to late here for me to figure out if you have a feedback loop which probably you don't by the sound of it. Then again maybe you do. Follow your signal from all sources, any chance it can be fed back into itself?

[VirtualMark]

I have this problem with my rokit 8's. I live in the UK, so its interesting to read that others outside the US have this problem. I fixed it by earthing the outside of my usb interface to my pc case, i don't know if this is correct or not but it stopped the annoying hum.

Strange tho, as no other equipment i have used has this humming. By the sounds of it, its probably a problem with the crappy krk's. I'm not impressed with them at all.

[kingbananathe]

get shielded cables

[kyle g]

shielded cables from my mixer to my breakout box or shielded rca's for my decks? or all shielded? sounds pricey

[Basic A]

how long are your RCA's?

[Promise One]

1. I have a soft high pitched humm and static kind of sound from my KRK's, this happens even when the computer is turned off. It is quite soft and not noticable when music is playing but i'd rather it not be there. Or is this normal?

Does this still happen if you turn on your KRKs with no audio cables connected or changing the input gain control (if it has one) to zero?
Have you tried plugging in somewhere completely different in your home?

Check your Delta soundcard settings, might be something to do with unbalanced connections, RCA or Jack. XLR is balanced and offers better noise and interference rejection.