achieving rock solid sync with external hardware

[Dark Arps]

I am having an absolutely awful time trying to get my external hardware to lock solidly to Logic's clock. I prefer using Logic over Ableton when it comes to composition and arrangement... I use Ableton for live performance and it is as tight as a drum, mainly because I use the Elektron Machinedrum (or Octatrack) as the master clock, Ableton parses that incoming clock back out to all the other bits of hardware and everything seems to stay perfectly in sync with no drift or jitter.

 

But when using Logic as the master clock and selecting "All" as the MIDI clock destination, the timing between Logic and the hardware is intermittent and sketchy (not so however, if I select two individual outputs as destinations, but I have more than two outputs I need to send clock to). There is also an issue with hanging MIDI notes. Whichever channel I have selected in the arrangement will sometimes receive a hanging note when I stop playback... I will have to double click on the MIDI out panel in the transport to send an all notes off function to eliminate the hung note. Also these problems seem to develop over the course of a session and are often fixed after a restart, but then develop again over time. Sometimes all MIDI functionality will cease for a few moments and then the floodgates will open resulting in a cacophony of MIDI notes sending to the track's destination, as if they've been piling up against a dam. I have also tried using IAC Bus as the clock destination and using MIDI Pipe to parse that clock data out to the various physical MIDI outputs, instead of using "all" as the destination... this does seem to work quite well but does not result in absolutely perfect, consistent sync, and the other problems with hanging notes still occur. How I test this: hit play on Logic with the metronome active, place a note on the downbeat of each piece of connected hardware, or set up an arp, so that all note events are hitting on the 1/4 note, and I listen closely for perfect sync, adjusting the clock sync delay parameter until it sounds locked... usually I need about 10ms delay to get things synced up. The best situation I am able to achieve is one where sync is good for an indeterminate number of bars, but then there is some kind of hiccup and the consistency of the clock is interrupted slightly... meaning that any hardware that is synced to the clock does remain in sync but any external hardware running at the same tempo (but not receiving clock from Logic) will now be out of sync... for example, I have my Octatrack connected to receive Logic's clock, and we are working at 126bpm. I set up a drum loop on a Teenage Engineering PO-12 (a mini drum machine basically) which is feeding into the Octatrack's input. I set the PO-12 to 126bpm, and start playback manually to sync to Logic. I can usually get this pretty bang on... it will remain in sync with Logic for a while but inevitably there will be some kind of stutter and I lose sync.

 

So basically I would like to know, what is the most reliable, stable solution for a problem like this? Logic does not accept incoming MIDI clock, but it does accept MTC. Could I benefit from buying a MTC-generating hardware transport device, and would I be able to use Logic to parse this clock directly out to my hardware, and would this result in solid sync? Ideally I am looking for something that is accurate right down to the sample-level but I have no idea if this is even possible. Any help would be greatly appreciated!