When I have mastering plugin chain in the main bus, that includes some heavy plugins that push latency, My outboard synths triggered by MIDI and routed to an audio track (with monitor on, or with "external input" plugin) are out of sync! They sound late and it just falls apart. When I clicked "PDC" button on transport, timings change, but are still out of sync. With mastering chain disabled Everything is in perfect sync. What can I do to make sure my MIDI gear stays in sync even with lots of plugins in use? I can't mix down anything! The moment I use heavy plugins everything falls apart! All PC-based tracks and VSTi are in perfect sync, byt all outboard MIDI synths fall behind. It seems like a very basic stuff, but I just can't make it work. Any advice appreciated!

Turn all your external midi parts one by one into audio so they end up like audio tracks like the other Tracks in your session. Make sure there is no heavy audio processing going on while you do this to make sure everything is in sync.  It is wise to have any external midi parts turned to audio even for your own record. You may not have the hardware later then you would not be able to play the session correctly say a year later. Also if you want to give the audio tracks to someone else to mix you can because you have all the parts in your music as audio files which is good thing.

You should not be doing heavy mastering processing while doing a mix, it is actually not the right thing to do anyway. Others may disagree but it is best to get your mix perfect without any heavy mastering processing going on. Live with the mix for a week and you will end up fine tuning it. Master after about a week and you will have fresh ears to make the right mastering decisions. Making important mastering decisions while you mix is not smart.

And while you are mastering a week later you are only playing back one stereo file on one stereo track. You can then use all the heavy mastering processes you want and it won't matter. The plug in delays that are occurring here won't have any adverse effect on your audio as it should be.

Well, thanks, but that's not a solution but a workaround. I'm not mixing with mastering chain in, but as this is a studio project and I'm recording people one by one over a long period of time, I'd like to turn mastering on sometimes for a rough mix to approximate the final result: it consists of EQ, mastering compressor, harmonic enhancer and limiter, so the result is much louder and polished than just a mixing bus out. Because live tracks (where MIDI is getting replaced by live instruments) may sound very different from MIDI, I need to keep MIDI as MIDI for as long as possible, as I may change anything when closer to the final mix. It would seem a trivial task to match MIDI out and audio in (monitor) delay to be the same as PDC... But it doesn't work. It's a huge bug I think. Besides, bouncing 16 MIDI tracks to audio and then rebouncing when anything changes is a huge PITA that should not be necessary.

OK I can see where you are coming from more so now. First the mastering chain. Two things you still don't need it during any tracking or mixing. The volume, turn it up!. Why cannot you do that? The EQ in the mastering chain can also be applied back at track level individually. So the polished sound can actually be created without the mastering chain in if you are good. This is good practice because when you get you mix sounding almost mastered (EQ wise that is only) it means less mastering is actually required later on and that is a good thing. 

Harmonic enhancers are also not a good thing to be using on your masterbuss. Get the sound the harmonic enhancer is doing back at track level and only on the tracks you need and maybe use EQ instead. You are mad to run your entire mix through such a crude effect as an harmonic enhancer. You have got no idea what that is doing to your mix. It is altering it's integrity big time.

Midi should be OK when things are set up this way and leave your masterbuss alone. I can see why you would want to keep midi as long as possible. Although it is still not hard to convert to audio and then go back to the midi track if you need. But if you are replacing midi parts to live performances then I see in the end you would not need the midi at all.

I sometimes still use external midi parts as part of the final mix sometimes myself but I will convert to audio as well as a backup. Sonar is NOT smart in the way it handles midi and audio sometimes. That is one of the reasons I use Studio One. It is way better and smarter in that regard.

OK, I understand that there is no solution, just worarounds. I did some more searches in the forum and this issue did came up in the various forms over few years. I'm very surprise why such a simple thing as automatic MIDI delay to compensate for PDC has not been implemened in so many years. Of course I'm not using mastering chain when tracking or mixing (usually). However because it involves console emulation, eq, enhancing and compressing - being sound-altering techniques it's actually very good practice to check mix with mastering on, or even mix last stagees with it being on, or "mixing into it". By "harmonic enhancer" I meant a harmonic enhancer/aural exciter specifically designed for mastering. It has several countours etc. Yes, I can turn mastering off, but what if I use any plugins that affect latency (like attach shaping of any kind or ohter look-ahead plugins) on tracks - the same thing will happen. And I can't bounce current version off for showing anywhere with rough mastering applied... Very disappointing. It would at least be useful to have a manual MIDI delay but there is no reason not to make it automatic.

In my experience both the outgoing midi and the monitored incoming audio from the external synths are delayed by the PDC amount, so the delay is double what someone might like in that scenario. The MIDI is PDC-delayed so that it will trigger the synth in sync with Sonar's audio output. Then the through-going monitored audio of the synth is PDC-delayed because it is passing through the same audio engine as everything else. 

But if I monitor the played-back external synths through their own amplified output, they sound in sync with the project audio. Note this, though: if I record the synth audio into a Sonar track, it is automatically shifted earlier in the time line by the PDC amount when the recording is complete, just like the recording of any other audio performance, so the recorded image is in sync.

This all would be the correct behavior if either 1) a person were performing MIDI live and recording the audio against an audio project, OR 2) a recorded MIDI performance is being bounced to audio (monitoring the audio track will sound wrong, but record right).

All these scenarios work best when monitoring the audio directly from the synth. Same with a live performer. Biggest problem is not being able to listen to the external synths (or any live performance) live through Sonar's effects. With PDC, there is no automatic solution for this, but a per-midi-track option would be nice for playback (not recording).

Hey Roman did you know that Sonar offers a Midi Timing Offset parameter which can be adjusted. It is not clear which version of Sonar you are using but I am sure all versions have it. It allows fine tuning of timing between midi and audio. Do a search in your manual and you will find it. This may help you line things up while you are using heavy audio processing plugins.

Thanks for this explanation! Now I finally understand what happens and why. Monitoring synth output live would sound in sync, but obviously I can't use it that way, because I need to do a rough mix and bounce to file for sending to musicians etc., and when I try "export audio" with MIDI synth input it gets out of sync too. Seems like for that I'd have each time to record synth track first and then export. Beats me why this has not been addressed for many years...

Thanks. This would be a PITA to adjust correctly, but I guess I could get a roughly OK sound for temporary mixes...

But how would you ever be able to export a mix that included outboard gear live?