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question for those who still plug in keyboards with wires into their audio interfaces


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I'm not a VST guy so I plug my boards straight in when I'm recording. one of my Korg keyboards is transmitting the slightest bit of noise which is kind of irritating. It doesn't come across in the general mix but I still want to lose it. When I crank it it reminds me of the sound of a dial up modem (or perhaps a cousin of that sound).  I plugged in my other board that has a balanced output and it does not transmit the faint noise signal that I described. Is it just a matter of spraying some contact cleaner about, or something more sinister?

www.youtube.com/ericjungemusic
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Are you saying the Korg that is making the noise is unbalanced, whereas the other keyboard--and the inputs on the interface--are balanced?  If that's the case, I've had some luck making "psuedo-balanced" cable specifically for connecting unbalanced to balanced.  It involves soldering a resistor inside of the 1/4" cable, if that's something you'd be comfortable doing.  It's been years since I've built them though, so I'll need to do some digging/Googling to figure out the details, resistor value, etc (if someone else doesn't chime in first).

 

Edit:

Below are a couple of links (with diagrams) for the cables I was referring to.  You'd have to buys some balanced 1/4" cable, and then an unbalanced TS connector, as well as a balanced TRS connector.  The connections are 1)Tip to Tip...2)Ring (of the balanced connector) to Shield (of the unbalanced connector)...and finally 3) the braid/shield goes from the Shield of the balanced connector to through a resistor and capacitor (in parallel) to the shield on the unbalanced connector.  My recollection of all this is fuzzy.  I don't even recall exactly why I needed to make these or what I was hearing; but I do know that they helped at the time, and I'm still using said cables in my studio.   YMMV 

 

https://www.soundonsound.com/sound-advice/20-tips-reducing-noise?amp

 

https://www.soundonsound.com/forum/viewtopic.php?t=80701

 

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Yes - to my knowledge the KORG has unbalanced outputs so I'm not sure if that has something to do with the noise I'm hearing. I also tried running the headphone output from the KORG to the audio interface and still heard the noise. 

 

that's really interesting but sounds a bit beyond my skillset. I don't have any soldering tools.

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I think I can eliminate the balanced/unbalanced theory since I'm testing out the connection on other unbalanced outputs and I'm not getting the same results. So it must be an issue with the KORG. I'm thinking dirty contacts or maybe some other issue (grounding?)...

www.youtube.com/ericjungemusic
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It could be oxidation on contact points, outputs are certainly worthy of maintenance. 

Some electronic devices are not friends with other electronic devices. Sensitivity to noise radiation. 

 

My Mackie MR5 monitor speaker will start sputtering and humming if I put my Android phone anywhere near it. Obnoxious. 

 

Location and position of various bits of gear and conveniences can make a difference, also worth investigating. 

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It took a chunk of my life to get here and I am still not sure where "here" is.
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I seem to have found the issue! When I connect the KORG to my PC via a MIDI USB wire, the noise starts up. No noise otherwise.

 

I guess I'll be using 5 pin and/or trying a different USB MIDI wire.

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I've had this many several times where USB is involved. As you've confirmed the problem disappears when using a MIDI DIN connection it's almost certainly a ground loop problem. ( DIN MIDI is isolated from ground connections).

You may get some luck adding filters, but it can be a bit hit and miss. Ensuring there is only one ground connection is generally a more reliable solution.

 

If you do need to use USB MIDI then it's probably best to use that as the only signal ground connection. That will mean isolating the audio signal output from ground.

 If you have a balanced audio output you can usually simply disconnect one end of the cable screen, leaving the other end connected. But only disconnect a signal ground (cable screen)..... NEVER disconnect a safety ground.

 

Or you can get complete isolation by adding a transformer isolator. I find the ART DTI very good .. or maybe a Behringer HD400 which also works well in my experience, and is cheaper...

 

I believe you can also try and isolate the USB connection ground, but that is likely to be a more expensive solution....

 

You might get lucky simply adding an RF filter, but it's a less predictable solution....

 

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Yamaha - YC61 - P105 - MOX6 - HC2 -- Neo Vent 2
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7 hours ago, KeyboardEric said:

it reminds me of the sound of a dial up modem (or perhaps a cousin of that sound)

Good description! And yup, when you hear that sound, it's almost certainly USB, and the easiest (but not only) fix is to use 5-pin MIDI if possible. It's been an issue discussed here going back at least this far... https://webcache.googleusercontent.com/search?q=cache:HtRyMDNnwJkJ:https://forums.musicplayer.com/ubbthreads.php/topics/2473835/Yamaha_CP33_USB_Midi_noise+&cd=1&hl=en&ct=clnk&gl=us

 

There are also isolation devices you can get, or some people just cut the ground wire in the USB cable...

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