Large amount of noise with USB Plugged in

tpantano · Post by **tpantano** » Tue Dec 08, 2009 10:40 pm

Whenever I connect my R3 to my computer via USB, my amp will start to buzz like crazy. Thing is, this happens even when the R3 is off! I can live with unplugging my R3 from my PC whenever I play or record, but patching is annoying.

I'm guessing it probably has something to do with the internal circuitry of the R3.... is there a way to fix this/can a korg tech do it?

P.S. I think I've seen a thread about this before, but I can't find it.

axxim · Post by **axxim** » Wed Dec 09, 2009 12:15 am

Hi,
connecting audio devices with computers is always a problem, specially with amps. I think this is not a problem of the R3 which is proved by your statement that it also happens when it is turned off. This problems are very frequent with all audio devices offering USB. That is why MIDI was or is (at least for me) one of the best digital interfaces between music instruments. It is galvanically isolated by optocouplers. The problems you are experimenting are the so called ground loops.

To solve this problems a little bit of tuning and trial is needed. You should set the input gains (i.e. of amps) as low and the audio outputs (i.e. instruments) as high as possible without distortion. This way the signals send thru the audio cables will have the highest level against electromagnetic noise. Avoid grouping (harnessing) audio cables with digital and power cables. Also avoid using unnecesary long cables. The same applies to the power cords, usually we all use extension cords that add noise (hum) to the signals.

USB cables should have noise supressors (those cilinders near to one end of the cable).

Sometimes adding aditional ground paths (cables screwed from one metal case to other) may help, but in other cases will increase the interferences.

I hope this helps a little!

tpantano · Post by **tpantano** » Wed Dec 09, 2009 3:21 am

I have plenty of MIDI cables at my house; However, can you patch from them? I'm guessing you can't.

axxim wrote:USB cables should have noise supressors (those cilinders near to one end of the cable).

I'm using a cable from my old printer, definitely not meant for music

So a type a male to type b male with a noise supressor will work better?

axxim · Post by **axxim** » Wed Dec 09, 2009 10:36 pm

I am using the USB cable that came with the R3? Didn't your R3 had one? I dont know if the one you use (the printers one) has a suppressor or not. Just try another one, but as said, USB is very noisy and the first thing you should do is set the gain and outputs as I told.

I dont know what you exactly mean with "patch from them"?

tpantano · Post by **tpantano** » Thu Dec 10, 2009 2:31 am

axxim wrote:I am using the USB cable that came with the R3? Didn't your R3 had one? I dont know if the one you use (the printers one) has a suppressor or not. Just try another one, but as said, USB is very noisy and the first thing you should do is set the gain and outputs as I told.

I dont know what you exactly mean with "patch from them"?

I bought my R3 secondhand, no cable. The cable im using is just Type-A to B, nothing else on the cable, so I'm assuming it has no suppressor.

And what I meant by "patch from them" was, 'Can I use the editor librarian through a regular MIDI cable?' The main problem I'm having is the USB cable causing noise while editing patches.

xmlguy · Post by **xmlguy** » Thu Dec 10, 2009 8:51 am

The noise is usually generated by the switching power supply in the computer that gets transmitted though the ground connection. The R3 has no reference ground, so it floats with whatever ground is connected to it. Some amps are more sensitive to a noisy ground than others, particularly guitar amps.

There's usually several ways you can stop the noise. You can use a powered speaker for monitoring, as it usually has its own ground through the AC cord, which can provide a stable ground reference that nullifies the noise. Or you can try another amp, or a different input on the same amp. It helps to have the amp/powered speaker connected to the same powerstrip, to reduce the chance of a ground loop due to different ground circuits. Sometimes wall plugs are on different circuits. The noise could also be affected by other loads on the same circuit, such as large motors, so trying a different circuit can help.

On a desktop PC, you might be able to change the power supply for a better one. That's usually not an option on a laptop computer. If you try all of these options and still have noise, then you can also stop using USB and connect using standard MIDI. A lot of audio I/O have midi, so this might only require buying two MIDI cables and changing the DAW configuration to use different MIDI ports.

The R3 really has nothing to do with this problem, directly, as this will problem can occur with any USB device on an external DC powersupply that shares a ground with audio inputs and the same computer. Extra care is required when hooking any computer to audio equipment to keep the signal clean.