Noise/hum when plugging into MIDI IN on SH1oh1

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jpmct
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Noise/hum when plugging into MIDI IN on SH1oh1

Post by jpmct » Thu Jan 23, 2020 8:34 am

I have a problem with noise/hum when plugging a midi cable into the midi in of the sh1oh1. My set up is simple -- I am just using the sh1oh1 as slave when clock syncing to external sequencer. The noise is present whenever the midi cable is plugged into the sh101 and stops when it is removed. I've tried replacing the s101 with another synth to see if the problem is from my other device but all other synths I've tried give a crystal clear signal when connected.

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tubbutec
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Re: Noise/hum when plugging into MIDI IN on SH1oh1

Post by tubbutec » Thu Jan 30, 2020 2:19 am

This is off for the simple reason that midi is not ground coupled. So there should be no additional noise via a ground loop.
Is the noise just there if you plug it in, or only if you also send midi? Does it go a away if you stop sending midi clock and notes?

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Re: Noise/hum when plugging into MIDI IN on SH1oh1

Post by jpmct » Fri Feb 14, 2020 12:47 pm

Hi, thanks for replying -- I can confirm that the noise is only heard when it's receiving midi clock and note messages. When I stop sending midi clock and notes from the master device the noise stops.

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Re: Noise/hum when plugging into MIDI IN on SH1oh1

Post by jpmct » Fri Feb 14, 2020 1:29 pm

The noise is easily heard on recordings -- any help/info on how to fix this would be really appreciated

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goldplate
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Re: Noise/hum when plugging into MIDI IN on SH1oh1

Post by goldplate » Fri Feb 14, 2020 1:30 pm

Maybe the internal MIDI cable is near a critical audio path ?

jpmct
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Re: Noise/hum when plugging into MIDI IN on SH1oh1

Post by jpmct » Fri Feb 14, 2020 2:36 pm

OK, I'm not technical enough myself to start opening it up and moving parts. Are there any other explanations that might be causing so I can pass this on to an electrician. Anything at all will be a help

Thanks

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Re: Noise/hum when plugging into MIDI IN on SH1oh1

Post by jpmct » Fri Feb 14, 2020 2:38 pm

"Maybe the internal MIDI cable is near a critical audio path ?" -- would it be possible fix this with little electronics experience?

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Re: Noise/hum when plugging into MIDI IN on SH1oh1

Post by tubbutec » Thu Mar 12, 2020 8:28 am

This might be a power supply issue. You might want to check your electrolytic caps.

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discomicke
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Re: Noise/hum when plugging into MIDI IN on SH1oh1

Post by discomicke » Mon Mar 16, 2020 3:41 pm

Following this. I have this exact issue as well. The noise is at manageable levels but a fix would be great.

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Re: Noise/hum when plugging into MIDI IN on SH1oh1

Post by discomicke » Tue Mar 17, 2020 4:14 pm

https://soundcloud.com/ubx127/sh101-mid ... se/s-nOgQu

Did a brief recording of noise levels. It's very faint but noticeable with headphones.

One interesting thing is that my MPC has 4 MIDI outs (3 of which are connected to the midi patchbay where the SH101 is connected), if I activate clock over several MIDI outs from the MPC the noise from the 101 increases. Might be a valuable hint for someone more technical than myself.

(Seems like comments are not visible on private SC links, MIDI clock is turned on about 4 seconds in)

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goldplate
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Re: Noise/hum when plugging into MIDI IN on SH1oh1

Post by goldplate » Tue Mar 24, 2020 10:13 am

jpmct wrote:
Fri Feb 14, 2020 2:38 pm
"Maybe the internal MIDI cable is near a critical audio path ?" -- would it be possible fix this with little electronics experience?
Yeah just move the internal cables position and at the same time check if the sound change depending on where they are.

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