hum from my new monitors?

Do you here it with a BLANK track playing?

Just curious, I get some noises here and there with nothing going on in Sonar but if I start the transport, it all goes away and doesnt export with the Mix.

hum is 100 percent a ground issue,am i wrong?
id go through every cable,plug,turn over every mattress looking for this offender.
sometimes its as easy as plugin in a ground surge into your amps plug or sometimes as hard a a TRS jack or a dirty pot somewhere in the chain thats shorting a solid ground.

grab the microscope and go scuba hunting

Sounds like its time to disconnect everything then start reconnecting just one thing at a time till you find the culprit.

You either need to get shielded RCA cables or use the balanced inputs instead of the unbalanced (RCA) input. Get a couple of TRS cables or XLR cables and that should fix the problem. 

From the other symptoms, it can also be electrical noise from the PC and the monitor. Maybe there is a shielding fault inside the speakers? I'd go back to the shop and try swapping them for another set to make sure you didn't get a lemon.

On the outside chance you are running a laptop, unplug the charger from the wall..  I used to use a Dell Inspiron for the longest time. No matter what I did (different power supply, ground lift), nothing fixed it.

L

While it's plugged in and humming, do this to check for a chassis short from one of your rca cables. Take your shoes off and touch (with your finger ) each of the rca connectors where they plug in to the interface. If it's a chassis short, the "leak" will go through you to ground and go silent when you touch it. The USB cable could mearly be the path of least resistance to the leak if it's jumping across the metal chassis of the interface. They are powered monitors so you should check the grounds on your monitor power cords as well. If they are bad they may send the leak to the speaker audio cables ground sheild . Tracing a ground leak can involve a lot of steps but starting with the touch the rca connectors step should isolate the problem to the monitors.

@M_Glenn_M

First, the hum you hear is probably the build-in USB hub running low on power. The hiss and noises you describe are a give-away for that. I see you have already worked that one out. If you have a PCI slot left you can consider to add an extra USB I/O card and use that solely for your keyboard. That way you do not have to use battery's etc., and your on-board USB hub does not have to deliver power for your keyboard.

About the noise from the fan etc.

I have a (in my opinion) quiet computer by using some "low noise" parts.

For cooling my processor I am using the Scyte Big Shuriken 2.
It is a difficult monster to mount, but it is extremely quiet and well worth the hassle.

As power unit I use the Cooler Master Silent Pro 600W.
It is not that cheap, but has a very low noise level.

As video card I use a fanless GeForce 8200, as that gives more than enough "power" to use with X1.
Obviously without a fan there is no noise.

My hard discs are mounted with the Scythe Hard Disk Stabilizer II.
Keep in mind you have to use the CDROM/DVDROM driver bay to mount the drives + damper.
Using this dampers, the hard drives no longer transfer their vibrations to the computer case, resulting is much less noise.

By using this measures I do not even need as special computer case, because everything is quiet enough.
These measures are not that cheap, but neither overly expensive.

Hope this helps a bit...

strikinglyhandsome1


"hum is 100 percent a ground issue,am i wrong?"

Hum can come from faults inside the electrical goods. The shielding isn't great either in some. Generally the hum is an outside issue. Cables and supply are first ports of call.

You could check if both monitors hum by just having one on at a time and setting them each up as left and right - on their own.

if these are faults of inside elecrical good,wouldnt that still be a ground issues(of a faulty electrical component?)
i thought hum is one thing,but shielding and interference is another story all together.