# Missing / dropped notes from time to time, how to debug? **URL:** \ **Category:** Using Zynthian\ **Created:** [January 30, 2025, 12:19am UTC](https://discourse.zynthian.org/t/missing-dropped-notes-from-time-to-time-how-to-debug/10949 "2025-01-30T00:19:00Z")\ **Posts on this page:** 10\ **Page:** 2

**Author:** ![rv5](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/rv5/32/13403_2.png) [@rv5](https://discourse.zynthian.org/u/rv5)\ **Post date:** [February 8, 2025, 1:46pm UTC](https://discourse.zynthian.org/t/missing-dropped-notes-from-time-to-time-how-to-debug/10949/21 "2025-02-08T13:46:21Z")

Going a bit crazy over this… Apart from the dropping notes in “busy” compositions, I also seem to get a lot of hanging notes even in simple compositions Currently have it with only 2 tracks playing. one plays 3 note chords with Dexed, other plays single notes on Noize Mak3r The moment I play these together, I almost immediately get hanging notes… I’m beginning to think there’s perhaps a hardware problem, like optocouplers failing on V5 batch? I don’t know. I just find it weird that I’m having so much problems and not everyone is having them. ```auto CH#04 NOTE_ON 77, Vel: 83 CH#04 NOTE_ON 82, Vel: 112 CH#04 NOTE_ON 84, Vel: 111 CH#06 NOTE_ON 61, Vel: 102 CH#04 NOTE_OFF 77, Vel: 83 CH#04 NOTE_OFF 82, Vel: 112 CH#04 NOTE_OFF 84, Vel: 111 CH#04 NOTE_ON 77, Vel: 83 CH#04 NOTE_ON 82, Vel: 112 CH#04 NOTE_ON 84, Vel: 111 CH#04 NOTE_ON 82, Vel: 112 CH#04 NOTE_OFF 84, Vel: 111 CH#06 NOTE_OFF 61, Vel: 0 CH#06 NOTE_ON 64, Vel: 102 CH#04 NOTE_ON 77, Vel: 83 CH#04 NOTE_ON 82, Vel: 112 CH#04 NOTE_ON 84, Vel: 111 CH#04 NOTE_OFF 77, Vel: 83 CH#04 NOTE_OFF 82, Vel: 112 CH#04 NOTE_OFF 84, Vel: 111 CH#06 NOTE_OFF 64, Vel: 0 CH#06 NOTE_ON 60, Vel: 102 CH#04 NOTE_ON 77, Vel: 83 CH#04 NOTE_ON 82, Vel: 112 CH#04 NOTE_ON 84, Vel: 111 CH#04 NOTE_OFF 77, Vel: 83 CH#04 NOTE_OFF 82, Vel: 112 CH#04 NOTE_OFF 84, Vel: 111 CH#06 NOTE_OFF 60, Vel: 0 CH#04 NOTE_ON 77, Vel: 84 CH#04 NOTE_ON 82, Vel: 111 CH#04 NOTE_ON 84, Vel: 97 CH#06 NOTE_ON 61, Vel: 102 CH#04 NOTE_OFF 77, Vel: 84 CH#04 NOTE_OFF 82, Vel: 111 CH#04 NOTE_OFF 84, Vel: 97 CH#06 NOTE_OFF 61, Vel: 0 ``` I count 20x NOTE\_ON in this example, and 17x NOTE\_OFF. So there are NOTE\_OFFs missing. I have a ton of other MIDI gear and nowhere do I see any similar issues, so the problem must be either hard or software on the Zynthian. Was planning on playing live in 2 weeks with the Zynthian as main source of synth sounds. I’m pretty much stressing out about this now 😯 Here’s a video displaying the issue with hanging notes: [![](https://img.youtube.com/vi/wcOehKYX9pg/hqdefault.jpg "8 februari 2025") ](https://www.youtube.com/watch?v=wcOehKYX9pg) I’m now going to find my midi interface so I can make some easy to reproduce scenarios for the issue queue… Being a software engineer in a former life, I guess I will have to dive into the code behind all this if I want to achieve a fix before my gig. Is there some sort of diagram somewhere that gives an overview of how all the components interact with each other? I did check the documentation but I couldn’t find anything like that, so it’s hard to just dive in without a general overview. ---

**Author:** ![chrismat](https://discourse.zynthian.org/letter_avatar_proxy/v4/letter/c/67e7ee/32.png) [@chrismat](https://discourse.zynthian.org/u/chrismat)\ **Post date:** [February 8, 2025, 2:14pm UTC](https://discourse.zynthian.org/t/missing-dropped-notes-from-time-to-time-how-to-debug/10949/22 "2025-02-08T14:14:32Z")

Hi @rv5 Your video is really good at explaining your issue could you attach a midi file, similar to the video, I wasn’t able to reproduce (from listening ) from your previously attached file. I tested with both din and USB host. ---

**Author:** ![rv5](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/rv5/32/13403_2.png) [@rv5](https://discourse.zynthian.org/u/rv5)\ **Post date:** [February 8, 2025, 2:14pm UTC](https://discourse.zynthian.org/t/missing-dropped-notes-from-time-to-time-how-to-debug/10949/23 "2025-02-08T14:14:39Z")

Another example, just playing mutliple notes at same time from MIDI keyboard, usually results in hanging synth (in this case now, ZynAddSubFX) Midi monitor on Zynthian clearly misses some NOTE\_OFFs: ```auto CH#03 NOTE_ON 56, Vel: 74 CH#03 NOTE_ON 68, Vel: 74 CH#03 NOTE_ON 80, Vel: 74 CH#03 NOTE_ON 68, Vel: 77 CH#03 NOTE_ON 80, Vel: 77 CH#03 NOTE_ON 92, Vel: 77 CH#03 NOTE_ON 80, Vel: 43 CH#03 NOTE_OFF 80, Vel: 43 CH#03 NOTE_OFF 92, Vel: 61 CH#03 NOTE_OFF 68, Vel: 61 CH#03 NOTE_OFF 68, Vel: 61 ``` And strange enough: Why is there an extra NOTE\_ON on 80? I only played 6 notes. The last NOTE\_ON should be a NOTE\_OFF, as displayed by the midi monitor on my Hapax: ![IMG_3559](https://discourse.zynthian.org/uploads/default/original/2X/f/fe8d6ecc724b7f8873853a219ee6e84f0d074448.jpeg) This adds to my reasoning of data corruption on hardware level ---

**Author:** ![chrismat](https://discourse.zynthian.org/letter_avatar_proxy/v4/letter/c/67e7ee/32.png) [@chrismat](https://discourse.zynthian.org/u/chrismat)\ **Post date:** [February 8, 2025, 2:16pm UTC](https://discourse.zynthian.org/t/missing-dropped-notes-from-time-to-time-how-to-debug/10949/24 "2025-02-08T14:16:10Z")

> [@rv5](#): > > Midi monitor Is that on the midi through port ---

**Author:** ![rv5](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/rv5/32/13403_2.png) [@rv5](https://discourse.zynthian.org/u/rv5)\ **Post date:** [February 8, 2025, 2:18pm UTC](https://discourse.zynthian.org/t/missing-dropped-notes-from-time-to-time-how-to-debug/10949/25 "2025-02-08T14:18:22Z")

no, hapax is in between the Midi KB and the Zynthian ---

**Author:** ![rv5](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/rv5/32/13403_2.png) [@rv5](https://discourse.zynthian.org/u/rv5)\ **Post date:** [February 8, 2025, 2:21pm UTC](https://discourse.zynthian.org/t/missing-dropped-notes-from-time-to-time-how-to-debug/10949/26 "2025-02-08T14:21:50Z")

Won’t have time to check further in depth today. I’ll make it my mission tomorrow. ---

**Author:** ![chrismat](https://discourse.zynthian.org/letter_avatar_proxy/v4/letter/c/67e7ee/32.png) [@chrismat](https://discourse.zynthian.org/u/chrismat)\ **Post date:** [February 8, 2025, 2:50pm UTC](https://discourse.zynthian.org/t/missing-dropped-notes-from-time-to-time-how-to-debug/10949/27 "2025-02-08T14:50:13Z")

> [@rv5](#): > > Midi monitor on Zynthian Midi monitor on Zynthian is the webgui? ---

**Author:** ![rv5](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/rv5/32/13403_2.png) [@rv5](https://discourse.zynthian.org/u/rv5)\ **Post date:** [February 8, 2025, 2:51pm UTC](https://discourse.zynthian.org/t/missing-dropped-notes-from-time-to-time-how-to-debug/10949/28 "2025-02-08T14:51:58Z")

Yes ---

**Author:** ![rv5](https://discourse.zynthian.org/user_avatar/discourse.zynthian.org/rv5/32/13403_2.png) [@rv5](https://discourse.zynthian.org/u/rv5)\ **Post date:** [February 9, 2025, 3:15pm UTC](https://discourse.zynthian.org/t/missing-dropped-notes-from-time-to-time-how-to-debug/10949/29 "2025-02-09T15:15:56Z")

Okay, good news, sort of… I could 't find my Midi interface (meh) but I realized the Hapax itself is a Midi interface on its own. So connected Hapax and Zynthian via USB (Hapax in Device mode) and … **ALL ISSUES ARE GONE!!!** So I don’t get any dropped/missing notes at all. Everything is tight. I also never have any hanging notes… So at least I don’t have to stress any more for my live set, I can just use USB!. However I do want to investigate this further once I find the time. Especially want to focus on the Midi Through output from Zynthian. I have a gut feeling towards a hardware issue. ---

**Author:** ![chrismat](https://discourse.zynthian.org/letter_avatar_proxy/v4/letter/c/67e7ee/32.png) [@chrismat](https://discourse.zynthian.org/u/chrismat)\ **Post date:** [February 9, 2025, 8:03pm UTC](https://discourse.zynthian.org/t/missing-dropped-notes-from-time-to-time-how-to-debug/10949/30 "2025-02-09T20:03:02Z")

That’s good news at least, when you find time it would be good if you could produce a midi file similar to the video so that I can test it with my hardware. Since updating mine V5 & V5.1 to staging my issues have gone away. [Previous page](https://discourse.zynthian.org/t/missing-dropped-notes-from-time-to-time-how-to-debug/10949.md?page=1)