Noise Issue from USB

[DonaldM]

Not sure which forum to post this, so I'll put it here. For quite a while I've been battling a noise issue in my set-up. Part of it is a bit of static type hiss, and the other a bit of higher pitch whine whenever PT is booted up. I have the MBox2 Mini and that whine noise is a known issue. I've made sure my audio cables are connected properly and shielded and all that. After plugging and unplugging this and that, I discovered that whenever I unplug the USB MIDI cable from my Yamaha Motif XS8 (my main MIDI board), about 60% of the noise goes away, if I have PT booted up. The remaining noise will go away if I unplug the USB cable from the MBox. IN other words, with both USB's unplugged my system is virtually noise free. (well there's a slight hum if I push the volume to like 90% or more - but that's not an issue).

I've made sure my USB cables are not lying on or near any other power cables or audio cables, or wall warts or anything else. I at a loss as to how to get rid of this once and for all. My USB cable from the MBox is one of those high end gold connector ones with thick shelding around the wires and its only about 3 feet in length.

The little bit of whine noise will go away if I have the mix knob on my MBox all the way to the right! However, when you're laying down audio, that's exactly the wrong setting. Also, that little whine noise gets into the audio track when I record audio from any external sourse (mic, the Motif, or any other outboard gear).

I use a Mackie Onyx 32-4 as the main way I get audio into the MBox. The sub outs 1&2 of the Mackie go to the inputs on the MBox, and the outputs of the MBox go to channels 1&2 as inputs on the Mackie. The main outs of the Mackie go to the L/R monitors (my JBL's). (My gear list is below)

All of this works well for mixing, playback, or when I just want to sit and play my Motif without even having PT up. I'm virtually certain at this point that the noise issues are indeed the USB cables...but I clearly NEED the USB cable for the MBox, otherwise I can't record to PT. Also, I very often record MIDI and/or instrument tracks with the Motif as controller, so need that USB plugged in as well.

I'm looking for direction here as to how to proceed to fix this. What am I overlooking? What should I try?

I don't have a power conditioner....don't want to make the investment if it wouldn't fix the issue. I did try using the adapter plugs to the power outlets for my PC and the Motif. Didn't make any diff either way.

Suggestions? Ideas? Help?

[dave911]

Try turning off your monitor and see if the noise stops.
Also in your computer BIOS there may be a settting for Spread Spectrum Clocking which is worth a try.
Do you have an UPS, a good one?
I would try two setups:
One with everything plugged into the same UPS.
The second with the audio interfaces connected directly to the power lines or a second UPS.

[John_Toolbox]

My old mbox original had this same problem. I never did come up with a solution, I just chalked it up to being caused by the mbox being a cheap interface.

While the power suggestions mentioned here are good to try, I don't know if they will help. I seem to remember having the same issue even when running the mbox from my powerbook running from the battery(The only cables in the whole setup would have been the usb cable and a mic cable).

[DonaldM]

Originally Posted by dave911

Try turning off your monitor and see if the noise stops.
Also in your computer BIOS there may be a settting for Spread Spectrum Clocking which is worth a try.
Do you have an UPS, a good one?
I would try two setups:
One with everything plugged into the same UPS.
The second with the audio interfaces connected directly to the power lines or a second UPS.

By monitor, I assume you mean my PC screen. Haven't tried that...but I will. I don't have a UPS. As I said, I didn't want to make the investment if that wouldn't solve the issue. But it might be the only route.

[DonaldM]

Originally Posted by John_Toolbox

My old mbox original had this same problem. I never did come up with a solution, I just chalked it up to being caused by the mbox being a cheap interface.

While the power suggestions mentioned here are good to try, I don't know if they will help. I seem to remember having the same issue even when running the mbox from my powerbook running from the battery(The only cables in the whole setup would have been the usb cable and a mic cable).

John...now that you say that, I recall having the same issue when I first set up Pro Tools 5 years ago on my laptop! Even with the headphones. So....what you're really saying is: buy a new interface!!!

That explains the noise from the MBox...but not the Motif. Even with the MBox unplugged, I get noise from the Motif... but only when the USB is plugged in. I'm really frustrated by this as I'd like to have completely noise free audio going directly from my Motif into PT. Instead what I have to do is create a MIDI track of a part I want to play using a Motif sound and record that in PT. Then, I have PT play the MIDI track back and record the part directly into the Motif. Then I have to export that track from the Motif - but it can only be a 16bit wav file, then import that file into the PT session. A bit cumbersome...but at least they're noise free!

But when I want to record my acoustic guitar either using mics or even the built-in pickup output, or vocals with my mic - that little high pitched whine from the MBox gets on the track!

Why would Pro Tools ship a product with a problem like that!?????!!!??

Too bad there isn't some kind of USB power conditioner!

[DonaldM]

I appreciate the suggestions guys, I really do!!!! I've never heard of such a thing as a USB ground device..but is there such a thing?

[DonaldM]

I just had a thought...always a dangerous prospect. Everything I've read about this sort of issue seems to indicate that the cause of the problem is the fact that the USB device draws its power from the same source as the computer, ie, the USB cable transfers both information AND power. If the USB device, the MBox for example, is wired just right, there may not be proper grounding inside it, or not enough power, etc. But I have one of those powered USB multi boxes where you can plug in several USB devices at once to just 1 USB input. Since the relay box is separately powered, I'm now wondering if that might solve the problem.

Not at home at the moment, but will try this when I am.

[DonaldM]

Well, I'm happy to report success...sort of. My idea about plugging the MBox USB through a powered USB hub first really does help...I'd say that annoying whine is reduced by almost 85%. It clearly is a design flaw in the MBox 2 mini itself.

I had better success when I ran my Motif through the powered hub. I'd say that is virtually noise free now that way. But I can't plug both the Motif AND the MBox into the same hub...that makes the noise all come back. So, I need to get a 2nd powered hub so each has its own. Then, I think, it'll be as quiet as I'm able to get it.

As soon as I'm able, though, I will replace the MBox with a better interface, more suitable to my set-up. When I got it, I wasn't sure what I needed, so went for simplicity. But something with more inputs/outputs would sure be nice. I'd love the Mackie 1640i..but don't have an extra $1600 or so laying around!

I appreciate the suggestions - at the least you all confirmed my suspicions and we may have discovered a way to, if not fix, at least greatly reduce, the whine issue on the older MBoxes.

[John_Toolbox]

I wonder if the powered usb hub would still work if you made a custom usb cable that only had data wires in it... basically snip the +5v power.

Or better yet if you could mod the mbox to not draw power from the usb port at all and instead use an external power supply.... USB power really isn't meant for powering mic pre's... that seems to be the issue, the mbox is using the usb power for it's analogue circuitry.

[John_Toolbox]

Also, there are some usb cables that have two male connectors on the computer end, so that they can draw more power for an external hard drive. I wonder if using a cable like that would change anything...