Mclk (MIDI Clock Generator) plugin as Generator layer? [SOLVED]

I came across this plugin that is part of MOD:
It is what looks like a pretty versatile MIDI clock generator.
Would it be possible to load this (lv2) plugin outside MOD, ideally as a Generator or MIDI FX layer ?

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It is already available. Just enable it in webconf.


OOPs. Completely forgot that there are many more plugins in the hiding than what’s visible in the UI.
Thanks for your help !

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Hallo all,
Does anyone have practical experience with a this generator? I tried LV-2 Midi Clock Generator in MIDI-FX layer and in MOD also. Unfortunately, I didn’t catch any midi messages on my PC.

@ToFF it looks like MIDI Clock Generator isn’t working as expected. It does not seem to be sending clock messages. This is odd because we used to use it to drive teh step sequencer (before we integrated it with jack transport). There is a plan to add MIDI clock to step sequencer but that might not be immient due to other commitments.

Sorry - I was using gmidimonitor which does not show clock messages. Using jack_mclk_dump I can see that this is working. If set to free run then it will create its own stream of MIDI clock at the rate set in the plugin, assuming mode is set to “Clock+Transport+Pos”. Note that enabling “Rewind” seems to break it.

When sync is configured to "Host Sync (if available) then it locks to Zynthian clock. (Actually locks to jack transport which zynthian (step sequencer) controls.) The clock only runs when there is a sequence running and its tempo is controlled by the sequencer tempo. Song position is controlled by the sequencer too.

The MIDI clock is not routed through zynthian midi router. Its output is routed directly to the physical 5-pin MIDI output but due to a limitation (bug?) within the zynthian routing code it does not get routed to any other MIDI interfaces, e.g. any USB MIDI interfaces. You can do so manually by connecting with ssh and using command line routing tools or running patchage (needs to be installed first) with X-forwarding or in VNC.

[Edit] Another apology. There is a bug in Zynthian which stops it routing anything to MIDI outputs with spaces in their names hence I can’t route to my USB MIDI devices. MIDI clock is routed to all physical outputs by default (except those affected by this bug).

@riban thank you for the detailed explanation of the situation.
I had the idea to work around the limitations of the current state of sooperlooper, where multiple instances are not synchronized.
The basic points were as follows and were based on what I have on my desk:

  • setting the tempo in Zynthian
  • sending a time message from Zynthian to BomeBox
  • depressing the FCB1010 pedal sending command for recording / playback to BomeBox
  • BomeBox would hear the timing message and manage SooperLoopers (i think about tree independents loops) in Zynthian at the right time.

Because my zynthian only has USB MIDI, I will not move further in the current situation.

I don’t know the plans of Zynthian developers in this area, but somehow I feel that it would be great to have your own “engine” for the Midi clock generator (robust and very accurate), which could be used independently and not only in the step sequencer. By the way, it’s great, I immediately started using it to practice scales with auxiliary beats when I play on wind controler.

Again, I have to thank you all who are developing Zyntian, it’s a great tool.


I am happy someone else also wishes for a Tempo setting above the sequencer.
For my way of working it is also essential to be able to set an overall Tempo and not only have it set in the sequencer when I don’t even use it.
Tempo is something above all like the Master Tuning is.
Time is the soul of sound and rhythm and lots of effects do sync to the tempo, if non is set, all is probably on standard 120 BPM.


With my setup I would appreciate if Zynthian would handle “the other way around” as well: Receiving clock messages and properly syncing to them. Currently this does not work (at least here) as I can see plugins and MOD-UI receiving the same clock message twice (MOD-UI shows exactly two times the bpm rate my hardware is sending out).

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I had this effect on my emagic MT4 MIDI hub and this happens when the SYNC signal is sent to more than one of the 8 available channels. If it is sent to one it is automatically available to all the others and if I would select a second channel to receive the sync i would get the double tempo.
So, this issue could be cause on your side. If you use a MIDI hub, make sure you only send the sync to one channel. I am using Ableton Live and I am not sure, if this might be DAW related or just the way the MIDI hub works.

@Eule I am not using a MIDI hub. It’s just one MIDI in port where the USB MIDI interface in the Zynthian box is receiving a signal from my setup. Just asking for clarification: Are you talking about ports or MIDI channels ? Clock is a System Realtime message that is not tied to any MIDI channel.

@catherder So, my emagic MT8 has 8 MIDI IN and OUT and in my DAW (Ableton Live) I can select in the MIDI settings to which MIDI ports I like to send a sync signal.
If I send the sync to any one of the 8 MIDI OUT ports the sync signal it is also on the other 7 ports and if I would select now a second port to receive the sync I am getting the effect you explain.
The receiving device would double up the tempo.
I never understood why this happens. It is no problem for me since I know this because when I make a session with my external devices, I want each one to receive the sync anyways.
If I want one device not to get synced for some reason, I just switch the device on the internal clock.

Another thing you should make sure, that you don’t send back the sync on MIDI through, because this can act like a MIDI loop and could also cause this tempo issue.