Stuck voices in synth while sequencing with hapax

I’m using the Hapax to sequence a Novation Summit via a standard midi cable, and it’s frequently triggering random voices, which continue to produce sound (on weird octaves), and as they keep hanging, they continue to sound even when there’s no more input.

30% of the time, sending the note stop trigger from Hapax helps to end the triggered voice(s), but most of the time I have to switch to another preset and back on the Summit to end the sound coming out.

This makes it impossible to actually play at all; it happens about every other minute, so I can’t even keep a 4 bar loop running without having to stop and reset the Summit or repeatedly press the Hapax’ stop button…

Is there a way to avoid this? Did I miss a (output) setting on the Hapax that avoids this from happening?

I have tested solving it by avoiding my midi splitter (no effect) and by using another hardware sequencer (Torso T-1) but then it does not happen at all, so I am presuming the issue is happening inside the Hapax output signal.
Just installed the new OS1.14 right out of the box, as this is the first day using the Hapax, I haven’t tried older firmware at all.
Edit: It is also consistently happening on the Moog Subsequent 37. Have to push stop-stop about every 2 bars to avoid the synths going in an infinite soundscape.

You have a Midi loop. How to go about preventing it from happening depends on your midi setup. The two basic options are either 1) disabling midi thru on Hapax or 2) setting Local to Off on your synths.
If you have a master keyboard to control desktop synths for example you’ll need MIDI thru on Hapax for that.

Thanks for the response! I’ve tried both options but sadly the random voices keep triggering on both synths. In the sub37 paired with severy note drops or non triggers.
The triggered voices are also mostly a few octaves higher that what I play in the pianoroll in the Hapax.
I’ve tried local off and midi thru off (which seems standard on the Hapax). Disconnected and turned off all midi out from the synths and turned midi in in off in the Hapax but to no avail.

Also tried midi port C with a lower ppqn and the D mini jack port, but the problem persists.

Anything else to try? Or is it just faulty and do I need to send it back to the shop?

Edit: I have discovered it does not happen when I connect the Hapax to only the Novation Summit. The problem starts when I connect more Synths to the same midi signal. Plugging them all in a different output of the Hapax sort of solves it for now. This just makes the routing more complicated because I want to connect way more devices than there are outputs available. Going to try daisy chaining and see if that works.

It sounds like an issue within your setup. Not something caused by the Hapax, since (as I understand) it doesn’t happen when you connect a synth directly to the outputs of the Hapax.

Also, I haven’t heard anyone with similar issues (not caused by user error/setup issues), so it is highly unlikely that it is an issue with the Hapax.

Can you describe your complete and detailed setup and routing?

Allright, so it’s been a while since I had the chance of getting things up and running so I hadn’t checked this forum while I was out of town for work.

I’ve discovered the issue primarily was caused by my midi splitter: the Esi m8u ex. This thing was functioning as a 1-in, 15-out to control my setup, and it turned out to be really glitchy in this configuration.
Have been in contact with their customer support but after one response they decided to stop answering, saying it could not be their product causing this.
This led me to sell the unit and replace it with a Kenton midi thru-12 which has been wonderful in his task of feeding my synths with the Hapax’ midi signals. No more glitches at all, ever again. I hoped…

Up until recently I bought a Behringer pro-800 and decided to hook ik up directly to the Hapax to try it out: suddenly there were stuck voices again all over the place. Just using the Hapax midi out 1 > pro800 midi in, and the Hapax live keyboard mode. (Brand new midi cable as well).

I have yet to try it with the Kenton device inbetween, which may be the key here to avoid the overflow of signal or whatever it is. Just updated both devices to the most recent firmware but that didn’t help.

Will test some more because I still can’t figure out what exactly is happening.

Rest of my setup is as follows:

Hapax as the heart of things> midi 1 out>kenton midi thru 12>Summit, ms20, subsequent, trigon, minilogue xd, mbase, drm1, jx-08>mackie vlz2404>speakers.
Hapax midi out 2>Torso t1> kenton midi thru 5> optional synth hookup.

Edit: also, there is no midi returns or daisy chaining happening at all. All devices have their own cable (from the Kenton thru) and midi channel (assigned in the Hapax) and none have a midi-out cable connected.

what os on hapax?

currently on 1.16

a lot has changed, i recommend you update

allright I’ll give it a try for a few days and see if that changes things. Hope this fixes the issue.
Thanks for the help!

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Just to share my experience, I run my hapax with 16 or more midi devices.
It hasnt suffered from stuck notes with almost every Midi & usb connection in use.

Try using midi thru ports on your gear (thru not out) and skipping the kenton thru device. it could be that thats dropping note offs and its one less thing to trouble shoot. Im on the latest firmware but havent suffered with hanging notes on any of the firmwares so far.

I did a little search to see if i could find anything to help and came across this Stuck Notes with Kenton MIDI Merge 4 : DelugeUsers (

Might be nothing but the last comment is removing the thru box fixed the issue. Good luck, I hope its solved quickly.

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I’m running the 2.0RC and have had this issue come up a few times. One of the tracks uses an FH-2 to convert MIDI to cv and gate for a eurorack voice. However the track where I experienced this last night controls one of the direct CVG outs on the Hapax. Definitely seemed to have a build-up and sustain effect described above.