External MIDI synths out of sync

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.

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.

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).

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...

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

In answer to you both (typed a long one first and it was eaten by the forum somehow): I've been doing it for ages in Cubase, it's very easy and convenient. External synths' output plugged to soundcard's input and to its own audio track in DAW. Live monitoring is always on in such tracks and when live mixdown to file is done its input is mixed in together by the DAW. That also allows to put plugins on them, like console emulation, EQ and noise gate for example, doing a final mix, and run it through the mastering chain - all in the DAW. Mixing it externally on analog mixer is not a good option for me, because then I can't do mastering right on the main bus, which is very convenient. And no recall - so I can't get back to it later and get exactly the same mix. Also, I don't have a high-end analog mixer and there is no point doing final mixing outboard otherwise.

I've been doing this in Sonar before, not just Cubase (just real-time mix with "include live inputs" gives you the same mixdown), and it was working fine until I started doing mastering ITB as well. When I was doing mastering on the final mix file later, delay was not noticeable (but it was there I guess). I do have a decent analog mixer, so that's not the problem, also my Tascam FW-1082 audio interface can monitor and route inputs separately. I just want to do it all ITB on the fly. It's easy, convenient and is technically possible. But because this stupid bug it's not workable in Sonar with mastering or other delay-compensation-inducing plugins.