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  1. Rando
  2. Getting Started with MIDI
  3. Thursday, 22 November 2018
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HI,
i tested the signals of my good old Technics SX P50 piano with the Midi-OX software. Most keys send the right ON/OFF signals, but 16 of 88 keys send no OFF-signal when I release a keay. Insteat they send a second ON signal. What i can do to fix this issue?

  • might be dust the problem? -> Opening the piano and cleaning everything carefully.
  • might be the cheap midi interface the problem? -> buy another one
  • can this repaired at all?


Thank you for your help.

Edit:
1st. Thank you for the replies and yes, i got a second on signal with velocity zero. Fortunately the piano from the 90's is not broken, so no repair or cleaning necessary. I bought another more expensive Midi-Interface (Roland UM-ONE mk2) and with this one, every signal was as it should be. No problems at all.
One of the sellers mentioned, that in the 90's there were a non-standard midi (format) used by Roland, so may be my old piano used this as well. Or the cheap interface (from china) was just broken.
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A note-on message with a velocity of zero must be interpreted as note off. But I guess you do get a non-zero velocity in those messages?

What device are you using to get the MIDI into the computer? Some interfaces are just broken.

If only certain keys behave like this, then it might be a problem with the keyboard itself. If those 16 keys are consecutive, then it's obviously the hardware that handles those keys.
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Hello Rando,

I've just looked at the manual for this keynoard, and I note from the Midi Implementation Chart that it does NOT support explicit Note Off, but ONLY Note ON with Velocity=0.

So, as suggested by Clemens, I'm sure you're referring to seeing Note On with a velocity NOT zero when it ought to be zero when you say Note Off.

It may be important to know WHICH keys are giving this problem. As well as that, when you monitor via MidiOx, it would be interesting to know what the velocity numbers are for the messages that OUGHT to be zero (Note Off), and how those values relate to the previous Note On messages. Maybe the velocity sensor is sticking?

MidiOx will record. And the data can be saved as a midi file. It would be useful if you could record something (even a few seconds of sound) including both the keys that seem to work OK and those that cause a problem, then ZIP the midi file and attach the ZIP file to your next message. Might tell us a LOT.

Geoff
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Rando,

Your edit does not make sense.

Note ON with Velocity=0 is an entirely normal (and correct) way to instruct Note Off. Also, that is the ONLY way that your keyboard sends Note Off.

OK, you've now got a (better ?) USB interface, but what has actually changed? Maybe you've still got a problem that might come back?

Geoff
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