To make that clear from the beginning: Unless a new bug has been introduced Live can be a very stable MASTER. I had it running as Master to my external Korg 01/W for hours (!) without the two drifting apart audibly (running a click on both Live and the internal sequencer of the Korg).
As you can see all of this has been discussed and buried for a long time already within the depths of the Ableton forum (and other forums) already, so I mainly use quotes even when they are based on older versions of Live.DOM, Posted: Tue Nov 04, [u]2008[/u] 2:16 pm wrote:Can't confirm or deny this yet, but we will investigate.
In the past Ableton...
Two things I like to stress about this discussion:Timur on the Gearslutz forum wrote:tell their customers that this is only a "cosmetic" issue (meaning only the visual BPM counter is moving while the Clock should be stable). But that is not true as can be seen in these screenshots (showing Kontakt 3 plugin running as Slave to the same Master clock on the same computer via Kore 2 and via Live 7):
It should be noted that the higher the BPM the more a Midi clock signal will vary in its BPM value, but the relative percentage should still be much lower than happening with Live.
Workaround: There are two possible workarounds.
1. Use Midi Time Code instead of Clock Sync. Live can theoretically sync to Time Code sample-accurately (albeit Ableton Support denies that this is even possible I had two instances cancel/null/invert each other).
The drawback of this solution is that you have to manually set the tempo on the slaves. So if you are playing a set with varying tempi you have to watch out not to forget that.
2. Rewire Live as a slave to a Midi Sync stable master. That way the Rewire master will do the Midi sync part and control Live's tempo accordingly.
Drawback of this solution is that Live does not allow you to use external plugins while being a Rewire slave (I think only Reaper allows that).
Solution: Make Ableton fix their Midi Clock implementation.
1) You should *not* discuss BPM values when measuring the tempo of the SLAVE, but percentage. +-1 bpm at 100 bpm is the same 1% as +-3 bpm at 300 bpm, +-3 bpm at 100 bpm is the same as +-9 (!) bpm at 300 bpm.
You may notice in the above screenshots that the Kore+Kontakt instance varies bpm by a far smaller percentage compared to the Live+Kontakt instance. Both were running as slaves to the same Master clock (via jitter-free MidiYoke connections to a Master running on the very same computer).
2) You should not (solely) rely on Live's BPM counter for your measurements but use a third-party one, preferably a VST/AU plugin that comes with its own BPM counter, like Kontakt. That is because Live BPM *display* may vary from its real internal counter. And the above screenshot in fact seem to imply either that or imply that the plugin gets fed another bpm/tempo than Live is using for itself (I assume the first, not the latter).
Not to mention that "audible" measurements like listening for phase shifts with the same audio-clip running on Master and Slave can often better pinpoint any drifting/wobbling.