• Registered: 2019-02-01
  • Posts: 5

Topic: Are there any electric leakage from Analog Input4 to MIDI input2 in UC

Hi, I have used Fireface UC for several years in my developments. But recently, I encountered a strange phenomenon.

When I input modulated sine 1.76kHz signal to UC Analog input 4, I receive invalid MIDI message from UC MIDI input2 even though I remove MIDI breakout cable.

I have checked 2 UC and same phenomenon happens so it might be the problem of Fireface UC.

Could you tell why it happens?


*Although I prepare
- my environment detail
- wav file of modulated sine 1.76kHz,

I cannot upload them in this post. I can send you by e-mail if you require.

Best

Takeshi

  • waedi
  • DAW Mastermind
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  • From: Swiss Zürich
  • Registered: 2020-12-08
  • Posts: 4,541

Re: Are there any electric leakage from Analog Input4 to MIDI input2 in UC

Is it possible to record this invalid Midi signals ?
Is there something similar to the wave signal ?
If you increase the input gain, is it affecting the Midi signal ?
I can imagine this issue is possible as both inputs have ground contact but never heard before of such in this way.

M1-Sequoia, Madiface Pro, Digiface USB, Babyface silver and blue

3 Reply by takeshi.kuwabara (edited by takeshi.kuwabara 2024-04-26 08:06:45)

  • Registered: 2019-02-01
  • Posts: 5

Re: Are there any electric leakage from Analog Input4 to MIDI input2 in UC

> Is it possible to record this invalid Midi signals ?

I receive following MIDI

F1 64 00
F1 71 00
F1 0D 00
F1 52 00
etc


> Is there something similar to the wave signal ?

I only check modulated sine 1.76kHz.
*It is a test signal for my current development. I also check it will not happen for pure sine 1.76kHz

> If you increase the input gain, is it affecting the Midi signal?
Yes, if I decrease input gain, the frequency of the MIDI decrease. So, I imagine there are some electric leakages.

> I can imagine this issue is possible as both inputs have ground contact but never heard before of such in this way.
Do I need some electrical shield to Fireface UC? But MIDI1 is okay in same environment...

  • waedi
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  • From: Swiss Zürich
  • Registered: 2020-12-08
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Re: Are there any electric leakage from Analog Input4 to MIDI input2 in UC

A shielding will not help as the voltage bleeding happens inside the box.
An additional ground contact to an external ground wire from both inputs may help, I would just ignore it and use Midi input 1.

M1-Sequoia, Madiface Pro, Digiface USB, Babyface silver and blue
  • Registered: 2019-02-01
  • Posts: 5

Re: Are there any electric leakage from Analog Input4 to MIDI input2 in UC

>I would just ignore it and use Midi input 1.

Yes, I also think "never use MIDI2 and always use MIDI1" is practical solution to the problem. But I am a little bit SHOCKED because  I rely on Fireface in my development. So I want to know the reason.

  • waedi
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  • From: Swiss Zürich
  • Registered: 2020-12-08
  • Posts: 4,541

Re: Are there any electric leakage from Analog Input4 to MIDI input2 in UC

You are right. Why is the phenomenon only in Midi input 2, this is the question.
Voltage bleeding is a normal thing in audio equipment.
I'm curious for a valid explanation.

M1-Sequoia, Madiface Pro, Digiface USB, Babyface silver and blue