Dealing with some noise

[DonaldM]

I have PT LE 7.4 Win with MBox 2 Mini.

The audio input is routed from my Mackie Onyx 32 mixer. The output goes through the Mackie to my JBL powered studio monitors.

Sometimes when I turn everything on, I have this scratchy, hissy sound that is quite annoying. At first I thought it was the Mackie, or the monitors, or one of the other pieces of gear I have plugged into the Mackie. BUT, what I found is that when I boot up PT, the noise goes away...well almost...I'm always left with a little bit of high pitch tone, and even that goes away when I shut down PT. So I'm thinking its the Mbox causing the issues somehow.

Any thoughts on what I might do or try to solve the problem? It doesn't interfere with recording and no noise shows up on an audio track, so its not going into the actual session, as far as I can tell.

Thanks

[DGraham]

Take the output of your Mbox directly to your monitors if possible to be sure. There isn't anything between the Mbox and your monitors causing the sound. From what you said it does seem to be something to do with the Mbox, but just to be sure. Do you have any external drives hooked up?


The sound you're describing sounds similar to a sound that was being outputted from my system when I had a SeaGate USB external drive hooked up. I'd sometimes leave it plugged in and turned on prior to stating PT by mistake and would get a sound similar to the one you've described.
Hope any of this could be of assistance to you. If not, I'm sure some of the more experienced people here can help.

[DonaldM]

Thanks for the suggestions. I'm pretty sure its the Mbox causing the issue, just not sure why.

[zenstone]

hi,
i think im having this same problem.
i plug my active monitors directly into the mini and there is a high pitch noise.
when closing protools it stops.

maybe its the mbox...i dont know..maybe its the computer messing around with the usb signal?

[DigiTechSupt]

This problem has been found to have several possible causes:

1. Bad/nonexistent power ground. Check your outlets and make sure they have a proper ground.
2. Ground loops, usually caused by having gear plugged into two different circuits. You can try to connect all gear to one circuit to see if that helps.
3. Using balanced cables from the output of the Mbox 2 to your amp/speakers can also help.
4. Bad computer design - the computer is putting noise down the USB bus, which is being picked up by the Mbox 2. Some customers have reported success by using a Monster Ultimate Performance USB cable.


- Make sure you're using balanced cables on all balanced inputs and outputs in your system.
- Remember that the Mbox 2 outputs are unbalanced, and should use unbalanced connections. If your monitors accept only balanced TRS inputs, then you will need a TS-to-TRS cable for proper grounding. To make one yourself, solder both ring and sleeve to ground on the end of the cable that is connected to the outputs of the Mbox 2, and connect the balanced end to your monitors.
- Try using a power conditioner for all your electronic gear (Furman, Monster).
- Run your outputs directly to shielded monitors and not through a mixer to see if the noise goes away.
- Some noise complaints arise from noisey power supply units inside computers - try installing and running on another computer (or if you're using a laptop, unplug the power supply and run off of batteries to see if noise goes away).
- Unplug and turn off all unnecessary gear and run only the computer, the Mbox 2, and monitors.
- Listen through headphones. If the noise is not present, then the noise is occurring after the Mbox 2 (monitors or monitoring system).
- Make sure you're not running through a USB hub or other device - the Mbox 2 always needs to be plugged directly into the computer.
- Try all USB ports on the computer to see if the noise lessens.
- Trace your cable path for long cable runs, and isolate your cables from possible interference (other gear, flourescent lighting, CRT monitors, etc).

[paulrgmusic]

Hi

I had a similar problem with a high pitched noise whenever I started Pro Tools. It only happened with ONE of my pair of Alesis monitors. I tried everything - swapped them around, changed the leads etc. No matter what I did, it was always the same monitor that produced the hum so I assumed it must be the speaker.

I took the speaker back to the shop (I had only bought it a couple of days earlier) and they tested it on their Pro Tools rig. Guess what? It worked perfectly.

The solution was to use balanced TRS cables. I had been using very good quality guitar leads and assumed they must be fine as one of the speakers worked perfectly well. Bought the new cables and the problem disappeared.

Paul

[korkman]

A big thank you to Digi Tech support for the information in this thread. I have a variant of the problem, perhaps you could help me decide what the problem in my case is and how best to troubleshoot it:

I have recently bought a new computer and when the juice hits my Mbox 2 mini, my monitors start to whine. Observations:

1) No noise in my headphones
2) No noise when I use the same monitors and mbox but a different computer
--> would seem that the mbox is being less sensitive to the problem and that the problem is with the bad current as it hits the speakers, right?

I have tried:
- plugging the MBox into other USB ports in the same computer
- replacing the power cable with one that has some power conditioning properties (a very inexpensive one though, mainly protects against sudden charges)
- lessening the number of usb-connected devices and taking away all the power eating applications I could think of

Problem continues. First, then: IS THIS IS POWER PROBLEM. And if it is, should I perhaps worry not only about the noise itself but also whatever other effects the bad power might cause at some point to external hard disks etc? And second: WHAT SHOULD I DO NOW?

Ideas:

i) motherboard feeds bad juice through usb
ii) power supply in my Shuttle PC cannot keep the current stable, which affects the current going out through the usb, although not badly enough to disturb the mbox itself
iii) the laptop's power transformer protected against some odd effect that is not now protected against ??

Solutions: ??? I need help

[DigiTechSupt]

Problem continues. First, then: IS THIS IS POWER PROBLEM.

Maybe, though unlikely. It sounds more like bad computer design or some other issue within the computer that causes it to send noise down the USB bus.

What can you do? I'd say you have a couple options.

1. Try a Monster (or other brand) high quality USB cable
3. Try a powered USB hub - though this isn't supported, it probably will work and may isolate the noise so it's no longer going through the Mbox. I would try to get it from a place that accepts returns easily, in case it doesn't work for you.

[korkman]

Thank you, Support, that's what I'll do. I seem unable to find Monster cables in Finland, but I'll ask around for some other high quality or audiophile usb cables. In the end, if it is the mother whining, I may have to put up with it - or with her, eh? - oh, those mothers!

Petter