Computer noise carrying through USB Cable

sproyd · Post by **sproyd** » Fri Jan 14, 2011 11:51 pm

Hi All

New to the forums here but I am really excited at the chance that you gurus may be able to help me with my problem.

The setup:
- Windows 7 PC Desktop
- Pro Tools Le 8
- Digidesign MBox 2. Powered via USB.
- Korg microStation (there is no microSTATION specific thread, but I believe it works similarly to the microKORG). Powered via AC.

I have the MBox hooked up to the computer via USB which powers the unit as well as transmitting signal. The microSTATION L/R outputs run straight into the MBox L/R inputs and everything works well like this.

The problem:
However, as soon as I plug the USB into the microSTATION for MIDI and to use the included RTAS setup editor in Pro Tools I get a low volume high pitch computer noise coming through the system - it records this noise too if recording the microSTATION. It only occurs when the microSTATION is plugged in via USB to the computer. I have a relatively cheap cable (KORG decided not to include one) but tried switching it with the MBox's included USB cable and same problem. I've tried different USB ports and tried different AC sockets. Someone told me that the issue is the USB from the computer is sending a power signal to the microSTATION causing interference - how do I rectify?

xmlguy · Post by **xmlguy** » Sat Jan 15, 2011 12:08 am

Connect MIDI out of the MBOX to MIDI in of the microStation, then test it. If there's no noise at this point, then connect MIDI out of the microStation to MIDI in of the MBOX. If there's no noise, then you're done.

The problem is that your computer has a noisy powersupply, which gets transmitted through USB ground or USB power. MIDI in should have optical isolation to stop a noisy ground/power from getting transmitted through an audio device.

sproyd · Post by **sproyd** » Sat Jan 15, 2011 12:12 am

Hi

Thanks for your reply. Good idea but two issues
(1) Don't have any MIDI cables to test it but suspect it would rectify
(2) I need the USB connection as its not just MIDI that I'm after, I need to use the live microSTATION software to edit programs and sequences in the microSTATION and that only operates through USB.

Could I potentially get a better PSU to correct? Are there USB cables that don't carry ground/power?

Cheers

xmlguy · Post by **xmlguy** » Sat Jan 15, 2011 12:28 am

sproyd wrote:Hi

Thanks for your reply. Good idea but two issues
(1) Don't have any MIDI cables to test it but suspect it would rectify
(2) I need the USB connection as its not just MIDI that I'm after, I need to use the live microSTATION software to edit programs and sequences in the microSTATION and that only operates through USB.

Could I potentially get a better PSU to correct? Are there USB cables that don't carry ground/power?

Cheers

Try the midi cables first. The editor uses MIDI. The USB cable is not the only way to use the editor. Think of the microStation has having a built-in USB-midi interface inside it, except that USB isn't electrically isolated, while hardware MIDI is optically isolated. The editor should work through the MBOX.

In the editor, press the Global button. Then you can set the MIDI in and out ports that the editor uses to talk to the microStation through the MBOX.

sproyd · Post by **sproyd** » Sat Jan 15, 2011 7:21 am

So you are saying that I can use the editor RTAS plugin in PTLE through regular MIDI cables via MBox and not just via USB (as I thought)

xmlguy · Post by **xmlguy** » Sat Jan 15, 2011 7:31 am

Yes, it should work unless there is a problem with your midi drivers for the MBOX 2. The editors/plugins use a midi interface. USB is just a wrapper around midi. I haven't tried your specific scenario because I don't use RTAS, MBOX 2, or the Microstation.

I have the Microstation editor and it has options to pick the midi port. All the other Korg editors work over midi without USB, so long as the drivers for the midi interface work. That includes the X50 editor and it's VST drivers, which I personally own and have tested.

You should buy midi cables anyways, they're cheap, and since all the other options are much more painful, like replacing the power supply or the computer, then you might as well give it a shot, huh?

sproyd · Post by **sproyd** » Sat Jan 15, 2011 7:35 am

Spot on - will pick up some MIDI cables tomorrow and report back!! Thanks for your help so far dude!!

sproyd · Post by **sproyd** » Sun Jan 16, 2011 12:59 am

Grabbed some MIDI cables today and while PT receives the MIDI signal the plugin editor tells me it can't communicate with the microSTATION

xmlguy · Post by **xmlguy** » Sun Jan 16, 2011 2:43 am

sproyd wrote:Grabbed some MIDI cables today and while PT receives the MIDI signal the plugin editor tells me it can't communicate with the microSTATION

Did you download and install any newer midi drivers for your MBOX 2? The editor should show the MBOX midi ports in the drop down list. Did it show them? Did the noise problem go away when the midi cables were hooked up?

sproyd · Post by **sproyd** » Sun Jan 16, 2011 8:14 am

Hmm... using these MIDI cables MIDI routed through the MBox 2 is working perfectly fine and the computer signal noise is eliminated.

However, the plugin editor doesn't really work properly and won't sync with the microSTATION. It can receive MIDI messages but upon launch comes up with the following message

and then if you click OK you get

So it would appear the functionality is seriously reduced without USB...

The editor/librarian manual here http://www.korg.com/uploads/Support/mic ... 750000.pdf suggests that USB MIDI is the only recommended way of connecting the keyboard to the computer.

xmlguy · Post by **xmlguy** » Sun Jan 16, 2011 8:39 am

It appears that Korg has changed how the editor works compared to other models. That sucks. But there may be some other things to try.

One workaround would be to use the midi cables when recording to the computer, and USB to do editing, but that limits what you can do via the VST/RTAS plug-in.

Those errors you got were after changing the midi in/out settings in the Global page, right?

Another option may be to try a powered USB Hub. That might isolate the noise coming from the computer from reaching the keyboard.

You're using a mac, right? You might be able to go to an Apple store to see if the noise is a defect that is covered under warrantee. Perhaps you could test with another computer that's the same model to see if the noise is unique to your computer or not. It would seem to be reasonable for your computer perform properly for music production. The fact that you don't get noise via midi seems to indicate that the computer is at fault, not the keyboard.

Sorry for the bad news, but that's all I can think to suggest.

sproyd · Post by **sproyd** » Wed Jan 19, 2011 6:45 am

Those errors you got were after changing the midi in/out settings in the Global page, right?

Yup - and the standalone plugin works... to an extent (that's where the screenshots were taken from) - but the RTAS in PTLE doesn't work at all over proper MIDI for some reason! Won't pick up the keyboard no matter what...

Another option may be to try a powered USB Hub. That might isolate the noise coming from the computer from reaching the keyboard.

Had already tried this. Bought the best rated USB Hub I could find... no change noise still travels down the USB to the hub and through to the keyboard. Sold the USB hub now.

You're using a mac, right?

Nope Win7.

Any other ideas? I am happy to splash out on a new PSU if it solves the problem - anyone got any suggestions on a good one?

xmlguy · Post by **xmlguy** » Wed Jan 19, 2011 9:12 am

sproyd wrote:Any other ideas? I am happy to splash out on a new PSU if it solves the problem - anyone got any suggestions on a good one?

If you have a tower PC with a standard ATX PSU, then yes, that's the best thing to replace. The cheap OEM PSUs that come with many systems are often noisy for music production. I suggest you go to a local computer store that won't hassle you if you need to try a couple models, and so you don't have to wait for shipping turnaround. Get one with a big, quiet fan and ask a tech (not a salesman) which would be best that they have for music production.

synthjoe · Post by **synthjoe** » Thu Jan 20, 2011 1:06 am

xmlguy wrote:
sproyd wrote:Any other ideas? I am happy to splash out on a new PSU if it solves the problem - anyone got any suggestions on a good one?
If you have a tower PC with a standard ATX PSU, then yes, that's the best thing to replace. The cheap OEM PSUs that come with many systems are often noisy for music production. I suggest you go to a local computer store that won't hassle you if you need to try a couple models, and so you don't have to wait for shipping turnaround. Get one with a big, quiet fan and ask a tech (not a salesman) which would be best that they have for music production.

I'm not sure at all that a new PSU will solve your problem - it all depends on how the USB port is powered and how the Mbox generates from the +5V USB supply all other voltages required for its circuitry - plus isolation on its inputs, which is not particularly good, as you experience. The best bet would be to get a DI box (true isolation with transformer) for each of the two audio lines between your Microstation and Mbox.

I'm not sure whether an 'electronically floated' DI box (ike Behringer's DI-20, for example) will solve your problem, but even those might. What for sure will solve your problem is a transformer equipped passive DI box - there are lots of them on the market (might affect your sound slightly, thoguh - the cheaper you get, the more likely it is to happen). Either inquire at the store quoting your specific problem or make sure you get one with money back guarantee and try it for yourself at home. Should work without any doubt - unless you hear the high pitched noise directly from the Microstation using a battery powered headphone amp or similar on its line outputs when connected to USB only, i.e. no audio leads. Hearing the noise in this latter case means that your Microstation is likely faulty or the USB has indeed too much noise on its power lines, which might be due to the PSU or the motherboard, in most cases.

X-Trade · Post by **X-Trade** » Thu Jan 20, 2011 1:15 am

synthjoe wrote:
xmlguy wrote:
sproyd wrote:Any other ideas? I am happy to splash out on a new PSU if it solves the problem - anyone got any suggestions on a good one?
If you have a tower PC with a standard ATX PSU, then yes, that's the best thing to replace. The cheap OEM PSUs that come with many systems are often noisy for music production. I suggest you go to a local computer store that won't hassle you if you need to try a couple models, and so you don't have to wait for shipping turnaround. Get one with a big, quiet fan and ask a tech (not a salesman) which would be best that they have for music production.
I'm not sure at all that a new PSU will solve your problem. The best bet would be to get a DI box (true isolation with transformer) for each of the two audio lines between your Microstation and Mbox.

I'm not sure whether an 'electronically floated' DI box (ike Behringer's DI-20, for example) will solve your problem, but even those might. What for sure will solve your problem is a transformer equipped passive DI box - there are lots of them on the market. Either inquire at the store quoting your specific problem or make sure you get one with money back guarantee and try for yourself at home. I must work without any doubt.

This won't help because the noise is getting into the synth through the USB port.
I back up xmlguy's post that a new PSU is a good one to at least try, and isn't going to be too expensive.

If you're on a laptop, then there's not much you can do except for recording with the power supply unplugged. I've had this problem on a laptop before and the manufacturer typically refuses to believe there is even a problem, and third party laptop power supplies are usually even worse! So you're stuck if that's the case.

You could also try different USB ports. I've often found noise on one port but not on another, for example if you have front-panel or expansion card USB ports.