Scaler 2.0.7 Overlapping midi notes of same pitch causing stuck/hung notes

Hi, I’m new to the forum but not to Scaler. Since I upgraded to Version 2 (great features btw which will improve our music in so many ways) I started getting consistently hung notes. I investigated this issue further and managed to narrow the problem down to my primary midi keyboard Kawai VPC1 midi buffer messing up every once in a while the midi ‘Note On/Off’ message order it sends out to the VST host.

Every time the midi keyboard sends ‘Note On’ message for a note that is already playing and not yet realeased with a corresponding ‘Note Off’ message causes a stuck note in Scaler 2. This double/overlapping midi notes getting stuck happens with the latest Scaler 2.0.7 version, but the problem does not appear with the older Scaler 1.8.1 version, so the newer Scaler seems to handle incoming midi a bit differently, with less error handling causing instability.

If it does not break Scaler 2 midi stability in other ways I would ask if you could change the incoming midi note handling code of overlapping midi notes in Scaler 2 to how it is in Scaler 1.8.1 version. I believe this would help with other users experiencing stuck notes also as not all midi keyboards handle midi ‘Note On/Off’ messages perfectly all the time. With my other midi keyboard (Korg King Korg) this issue does not happen at all. I will contact Kawai support about it but I think fixing this issue through updating Scaler 2 midi code will improve Scaler 2 midi stability greatly for all of us.

The fix should be relatively simple, just keep all incoming midi notes in a buffer and check the latest incoming ‘Midi On’ message against all currently sustaining midi notes, if overlapping notes are found then add an extra ‘Midi Off’ message right before any new ‘Midi On’ messages for the same note number are processed preventing overlapping of the notes. Lastly in the code you probably can just discard all ‘Midi Off’ messages for notes that are not playing anymore without any negative consequences.

Note: This issue happens even when using the internal Scaler 2 sounds so its not about how Scaler sends midi out.

Here is a picture of the incoming overlapping midi notes from midi keyboard causing the stuck notes in Scaler 2 (midi data monitored via MidiOx):

I am not sure but I think this could also be linked to the other Hung Midi note topic:
Hung Note Only On Legato (Kontakt Spitfire strings)

Thank you for your help.


Good investigative work and we appreciate it. We shall look into this at our next round-table. Thank you.

Thank you Davide. Until the fix gets implemented into Scaler 2 there is a working but a bit cumbersome workaround for those who are experiencing the same issue for the same reason. The workaround is to use a midi FX / VSTi plugin which prevents overlapping notes of the same pitch, the plugin should be inserted before Scaler 2 in the midi processing chain. Doing this completely fixes the overlapping stuck notes issue for me.

One such free plugin is called “midiOverlappingNoteKiller” by Piz MIDI plugins, the developer does not distribute these anymore, but they can be still found via a third party website, there are both 32-bit and 64-bit versions of the plugins: Piz MIDI plugins

Elementalis, thank you for all of your great work on this which is greatly appreciated! You have summarized this issue perfectly and very succinctly. I too am having the exact same problem on Version 2.0.9 AAX (within Pro Tools) with hung midi notes utilizing the Kawai VPC1 midi controller and verified this using a similar midi utility application as well. I am embarrassed to admit the hours that I have put into researching how to correct this issue only to arrive with the same findings as Elementalis. Hung midi notes are occurring with the vast majority of my instruments and we would greatly appreciate a fix to this issue ASAP as it is difficult to use Scaler with this issue persisting.

Many thanks in advance for all of your help.

Hi @Donald,

thanks for reporting your issue. We pushed a fix for this in 2.0.8 but apparently it wasn’t enough to get rid of the issue completely.

We will have another look at it and try to get it fixed for 2.1.


Many thanks, Ed. Scaler is such an amazing tool and anything that you could do to address this issue soon would be greatly appreciated … thank you again!!


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Dear Elementalis,

I’m still having the same issue with using my Kawai VPC1 with Scaler @. Did you find the application “midiOverlappingNoteKiller” that you suggested to completely solve the issue with hung midi notes and is the download from a safe (virus free) website?

Thank you in advance for your help which is greatly appreciated!!

Best regards,


Dear Elementalis,

I’m still having the same issue with using my Kawai VPC1 with Scaler @. Did you find the application “midiOverlappingNoteKiller” that you suggested to completely solve the issue with hung midi notes and is the download from a safe (virus free) website?

Thank you in advance for your help which is greatly appreciated!!

Best regards,


Dear Donald,

Sorry that you are still experiencing this issue, I can happily report that for me the issue with Kawai and Scaler 2 is now fixed. A big thanks to the Scaler team for fixing this, its greatly appreciated and now I can use Scaler 2 finally in its full capacity.

I tested both the VST2 and VST3 versions of the plugin and they both work now without overlapping notes getting hanged anymore, just rock solid performance which is great. I’m using the latest Scaler 2.0.9 version in a 64 bit Studio One. Perhaps Pro Tools with AAX handles incoming midi somewhat differently I cannot say, might be something to check and compare in your system with some other DAW’s and with the VST format to be sure. I quickly tested the new Scaler 2 VST’s also with my older DAW Cakewalk Sonar and the hanging notes issue is fixed for Sonar too.

Something else that you might try is to test if there is any difference between the USB and the midi output of Kawai VPC1 if you have the possibility to do so. Using the midiOverlappingNoteKiller plugin before Scaler also fixes the issue completely so if you can try that its worth testing. The download was safe when I tested it with but its always a good practice to check downloaded files with a local antivirus program as well as upload and test it online after download for any possible viruses.

Also try updating the VPC1 USB drivers to the latest version if you have not already done so.

Hope you find a solution to the issue.

Best Regards,

Many thanks, Elementalis … I greatly appreciate your responsiveness and all of your great ideas!! Unfortunately, I am not able to use the midioverlappingnotekiller utility as it only runs on Windows PC computers and I am working on an Apple Mac workstation. I’m currently trying to find an equivalent plugin that will work on the Apple Mac platform with Pro Tools.

Scaler has always been an incredibly stable program for me and I have never really had any issues. The more that I think about my current issue with the overlapping midi notes, the more I think that the problem lies in how I am using the product which runs from PT in the Mac workstation through converters into a recording console and then back into the Mac workstation. Considering this application, even the smallest bit of latency may be enough to create this issue with overlapping midi notes.

Thanks again for all of your wonderful help which is greatly appreciated!!

Best regards,