As with most things, it really helps to first decide what setup you want and then find a solution for any issues specific to that setup.
The difference beteen jitter and latency
It’s also important to understand the difference between jitter and latency. Jitter is the variation in the time between subsequent clock signals, latency is the delay between when a signal goes in and when a signal comes out.
Both jitter and latency are inherent in any digital system and can’t be prevented completely. You can only try to reduce them to a level where they’re no longer an issue for what you’re trying to do, or you can find a way to deal with them.
Direct sync vs. derived tempo
Another thing that confuses a lot of people when they’re talking about MIDI clock sync is the different between devices that use the clock signal directly, and devices that derive their tempo from the clock signal.
When syncing to an external clock signal, older or simpler devices forward their internal sequencer a single step every time they receive a MIDI clock message. Subsequently, these devices can’t have a resolution of more than 24 ppqn and any internal swing will be disabled when they are synced to an external clock signal.
Modern or more complex devices derive a tempo by averaging incoming MIDI clock signal and use that BPM value to set their internal clock source when syncing to an external clock signal. This way, they can continue to offer a higher resolution than 24 ppqn and continue to offer features such as swing even when they are synced to an external clock signal.
Another advantage of deriving the tempo by averaging the incoming clock signal is that jitter is much less a concern than it is with direct sync.
Computers are often better than hardware (really)
If we’re talking about MIDI clock, it turns out that computers actually output a more stable clock signal over regular MIDI interfaces than most hardware devices. As you can read at https://forum.mutable-instruments.net/t/midigal-yet-another-midipal-inspired-project/6731/116?u=t2k, Ableton Live running on OS X with a simple USB MIDI interface can generate a clock signal that’s over 3 times less jittery than what comes out of an Analog Four or a RYTM.
It’s the latency, stupid
In most cases where people are complaining about MIDI clock, they’re actually dealing with the latency that’s inherent in adding external hardware to a DAW setup where the audio from an external synths that’s coming back into the computer through their audio interface is delayed in comparison to the audio generated internally by the DAW or any plugins running inside it.
Most DAWs will offer a way to resolve this problem by setting a per-channel latency value for external hardware. Some DAWs even include an automated procedure to measure latency and set the compensation delay.
Another solution to this latency problem can be to mix the audio output from your computer with your hardware synths using an external mixer.
Don’t buy the snake oil
Using a “sample accurate audio clock to MIDI sync” hardware solution can help on computer setups where you have trouble getting a MIDI clock signal out of your computer that’s properly in sync with the audio that’s coming our of your computer.
However, keep in mind that this does noting to reduce the latency issue of getting the audio from external synths back into your computer through your audio interface.
Also keep in mind that reducing MIDI clock jitter won’t make much difference for modern hardware devices, so the only thing you’re resolving with additional synch hardware would be a latency problem which you can often also fix by changing a setting inside your DAW.
Recommendations and suggestions
Ok, keeping all of the above in mind, you might want to try to go through the following list of suggestions:
- Does your external hardware use MIDI clock messages direct to advance it’s sequencer or does it derive the tempo and uses its internal clock? If the latter is the case, then some jitter in the MIDI clock signal is not really an issue.
- Do you want to bring the audio from your external hardware back into your DAW or do you want to mix everything using an external mixer? In the first case you need to deal with latency of incoming audio, in the second case you don’t.
- Are there any issues with the MIDI clock signal your computer generates and can you fix these by tweaking settings in your DAW? Can you update your OS or maybe even switch to a setup that’s known for better audio and MIDI support?
- In case you are not using your DAW as the master clock, make sure you’re using one that’s actually good at syncing to an external clock signal (e.g. Bitwig really is better at this than Live for whatever reason).
- If recording latency is an issue, maybe it’s time to get a new audio interface. These days you don’t even have to get a very expensive one to get low-latency audio input; even some of the recent cheap Behringer interfaces offer impressive low-latency performance.
Finally, your life will be better if you accept that there’s not a perfect solution that will make jitter and latency go away completely. Your only option is to work around it somehow. 