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  • Synchron Player v1.3.1137 causes audio driver loss in Logic Pro on M1 Ultra

    Yesterday I upgraded Synchron Player from 1.3.810 to 1.3.1137. Immediately after, I found that while playing a project in Logic Pro X 10.7.9 on Monterey (MacOS 12.7.1), Logic would play through once, but if I stopped the play and started playback again, there was no longer any audio output (though my audio device still appears in system settings and in Logic). I tried rebooting the audio interface, rebooting the machine, restarting Logic, restarting my MIDI devices, changing USB cable, using a USB-C instead of USB A, plugging into a powered USB hub instead of direct to the Mac, etc. The problem persisted.

    Today I downgraded back to Synchron 1.3.810, and immediately the problem went away. Unfortunately, I saved my project before downgrading. When opening the project again with 1.3.810 reinstalled, all my Synchron instruments in the project are empty -- i.e., the player shows no sample library selected. Fortunately, I was able to reconstruct it from a saved copy by copying new MIDI regions over, but I'm guessing the save format has changed as well, so that files saved with the new Synchron version can't be loaded properly with old versions.

    FOR THE SYNCHRON DEVELOPERS: I did find one web page stating that this problem can occur when "samples with very large magnitudes or even inf or nan values are sent to the audio driver". I encourage you to check Synchron 1.3.1137 to see if it is emitting inf or NaN values, as these may be causing problems for some audio drivers.

    My machine: Apple Studio 2022 M1 Ultra 128 GB RAM. Audio: Axe FX III USB.


  • UPDATE: today I moved my projects to a new 2023 M2 Ultra running the latest version of Sonoma (same audio interface), and so far this problem has not occurred with the newest version of Synchron and the newest version of Logic Pro X. The problem may be specific to M1 Ultra, to MacOS Monterey, or to Logic 10.7.9.


  • Now it's happening again, on M2 Ultra in newest version of Logic and newest version of MacOs Sonoma. It appears to only (so far) affect Strings Pro. I'm getting a +infinity on the volume, which is consistent with my previous post. Elite strings playing the same Midi region doesn't do it, and neither does Spitfire Chamber Strings.


  • Correction: it also occurs with Elite Strings. I have also ruled out my audio interface as the problem: the +INFINITY appears to disable the built-in MacOS audio driver, because if I switch to using the mac's built-in speakers, the problem also occurs. There is no sound, either for Logic Pro or for other apps, until I reset the audio driver in Logic by disabling and re-enabling core audio and pressing "apply".

    Once again, reverting to Synchron v810 eliminates the problem. This has now happened on two separate Logic projects, on two machines (an M1 Ultra and an M2 Ultra), in two versions of MacOS (Monterey and Sonoma) and two versions of Logic (1.7.9 and 1.81).


  • Is anyone else experiencing this? For Synchron 1.3.1137 the volume indicators in the Synchron mixer are spiking to large values, the MASTER spikes to infinity, and MacOS's audio is disrupted so that no apps produce sound until core audio is reset inside Logic. This is true for both my external audio interface as well as the built-in speakers. Logic 1.8.1, MacOS Sonoma, M2 Ultra.


  • Correction, Logic version 10.8.1.


  • I see the same behavior in Cubase M1 Max. It comes accompanied with a blast of sound. Switching the plugin off and back on fixes it. I hope they are able to reproduce it since I am not sure what logs to provide.


  • I’m having exactly the same issue with an M1 running the latest Ventura, Logic Pro and Synchron Player. The 1st trumpet in Synchron brass says it’s peaked at 600+ db and the level bar is at max, and then everything is silent. If I play back there is no audio, but trying again the audio is restored. This happens when trying to record a new part on another track, not sure if it also happens during playback as I was mostly replaying in new lines at the time it happened.


  • This is happening with Intel Macs as well, the latest Synchron Player in OS 14.1.1. Causes massive problems in Logic, exactly as listed above, and sometimes just altogether crashing LPX.