Midi sync to external clock — Dropping out

VCV Rack
#1

Just starting with VCV, it is a wonderful platform!

Running into trouble slaving VCV to my hardware setup though… Master clock is being generated by the E-RM Multiclock (an amazing unit!) into VCV via the core Midi module and then to Impromtu Clocked but the BPM is jiggling and cannot keep a tight sync.

Wondering about the communities experiences syncing with external drum machines, I imagine it is uniquely my problem but would be curious to know others experience.

I may need to find another midi interface to test, but cannot imagine that being the issue.

Thanks!

  • Edit: I found a spare Midi interface to test, but still having the same problem.
MIDI: your experiences and the state of support in Rack
#2

E-RM Midiclock is more stable in my eyes.
E-RM Midiclock to Kenton Thru to different mac and pcs with MIDI input at the interfaces works very well here. Just keep an eye on reseting all computers programs before you hit start!

#3

You also could use a metronome click that is distributed to the audio interfaces of the computers to get good results

#4

Thanks jue - Yeah the Multiclock is rock solid. What module in VCV are you patching the MIDI clock to?

#5

I think there is an open issue on GitHub regarding unstable MIDI clock.

#6

Right, thank you for telling me, was driving me crazy.

#7

Is the only stable external clock option an analogue pulse into VCV?

#8

Hi Evan!
Do you have the option to use some sort of an analog clock? I have also a few Midi devices but I always use the actual analog clock to sync with VCV and Clocked. You don’t need anything special for this, just send the clock to your interface and from there to VCV and Clocked. Just make sure it’s not going also to your speakers and such. Let me know if that works for you.

#9

MIDI Clock into interface MIDI into Numerology into VCV via IAC Buss

Works well with a MIDI note as trigger/clock and additional MIDI controllers

All my macs and a Laptop are in sync!

#10

Thank you for the advice Omri!

I am going to try that, makes much more sense in the context of a software modular environment anyway. More elegant. I was just reading in another thread where you said you are using the BSP as master, so now I understand that you are using it’s clock out.

Great!

Evan

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#11

Thank you jue!

#12

Yes, I always try to use the actual analog clock for sync. Let me know how it works.

#13

Testing it out now, much better but still a tiny bit unstable. Seems to be related to my CPU (which occasionally glitches and then the clock drops out — a bit strange coz I am using an iMac 3,4 GHz i5, but was just reading that VCV is using a single core, so I guess makes sense to run out of steam). Funny enough I am trying your tutorial now using the Euclidean & Golomb sequencers and there are TONS of modules on there. :wink:

Running the clock directly into an audio input, Clocked is receiving the clock but the LCD display flickers between numbers - is that normal behaviour?

THANKS!

#15

Ah! Got it sorted! Was using a clock divider on the Multiclock > into Eurorack > then into VCV. Needed to run the raw clock into VCV and use P24 mode on Clocked. Rock solid now! :pray:

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#16

Perfect! I’m happy it works :slight_smile: Now you should share some sounds with this setup :wink:

1 Like
#17

Sure will share!

What is the normal process for that within this forum?

I have a mutated version of your dual-sequencer running the VCV voices you had and driving some Eurorack modules plus a kick coming from the Alphabase. Pretty interesting start… Heading to bed but can post tomorrow.

#18

there is a music thread so you can post there. just make a new thread for your posts and add new post to there. can’t wait to have a listen :slight_smile:

#19

I have the same problem, no matter if I try to sync internally with Ardour or Renoise, or from my external Midibox Sequencer, a lot of pulses get dropped in VCV’s Midi-CV Module.

VCV-MidiClock
VCV-MidiClock.jpg1076×725 116 KB

On Linux there is a workaround with a modular-Pulse.wav send to sjack input as a clock

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#20

See my reply here: Midi clock renoise-vcv rack If you manage to verifyably pin the problem down to Rack’s implementation of MIDI clock, that would be great, then we can get Andrew’s eyes on it.

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#21

I would love to be able to pin it down profesionally, but I can only read and understand a portion of code and believe, that if it would be easy, it already would have been solved :wink: .

Midi-Clock was always not 100% accurate. Most Softwares have a sort of “smoothing” or “calculate average” to get a “stable” clock.

By design Midi-Clock is hex 0xF8.
And if I see it right, MIDI_CV.cpp (Line 229ff) from github, triggers a Pulse in dsp::PulseGenerator in case the Midi Message is 0x8. But that does not happen everytime. Also, it is somehow depending on the Sample Rate. Higher VCV Engine Samplerate creates more Pulses.

CV-Midi sets a boolean (0 or 1) in midiOutput.setClock, wich then sends the hex 0xF8 as Midimessage, that, when monitoring it with f.e. MIDI-OX is pretty stable. Problems I found here is that Midi-Message Start (hex 0xFA) and Stop (hex 0xFC) or Continue (0XFC) are not always transmitted, plus my Ardour and Cakewalk behave differently if VCV is set as Master (wich might be Ardours Midi-Implementation).

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