I ran into PDC side chaining problem this week. I was searching for a reason as to why my tracks were suddenly out of sync after side chaining a compressor on the bass bus (with 5 basses) to the kick buss (with 3 kicks), side chaining a compressor on the instrumental bus to the vocal bus, and using some latency inducing plugins like Soothe2 on all of my individual vocal tracks. Just read through this whole thread and wow... am both frustrated and really grateful for how thoroughly this issue has been documented. Thank you all. I've reported the bug too to https://www.apple.com/feedback/logic-pro.html. It really seems like a fatal flaw.
Are folks just not using side chains? Side chaining bass to the kick or side chaining instrumental bus to vocals feel like foundational functions... Just curious what people are doing to achieve this in light of this bug?
Anyway, I'm trying to write out my understanding of the workarounds mentioned here and in other forums and wanted to share where I am. Would love any additional insights/modifications to this list:
1. DON'T USE SENDS ON AUX/SUMMING STACK (IF POSSIBLE)
Ploki says he found if he refrains from using a send from an aux/summing stack, logic generally behaves
viewtopic.php?f=42&t=135038&start=120#p814388
2. TRY USING INDIVIDUAL TRACKS INSTEAD OF BUSSES/AUX TRACKS (IF POSSIBLE)
3. TRY AVOIDING LATENCY-INDUCING PLUGINS IN THE AUX TRACKS (IF POSSIBLE)
4. TRY PUTTING LATENCY-INDUCING PLUGINS BEFORE SIDE CHAINED PLUGINS (IF POSSIBLE)
en5ca's observation: viewtopic.php?f=42&t=135038&start=100#p800080
5. TRY USING DUPLICATE OR UNPROCESSED TRACKS AS A GHOST TRIGGER
Create new track. Copy of the trigger track (i.e. Kick) and remove processing or import original unprocessed audio if receiving files from client. Mute it and name it in helpful way. When using side chaining, use this track as trigger. If needed: Audition the side chain track and the original trigger track solo'd and slide the trigger track forward until it hits with the original through the compressor plugin.
6. TRY USING BUS WITH SAMPLE DELAY AS A GHOST TRIGGER
Suggested by StevenTOAST: viewtopic.php?f=42&start=20&t=135038&sid=88f2c4338e737b1ffd774b5a4cef9be2#p718622
Send the Trigger (i.e. Kick or Inst 1) to a bus, let's say Aux 1
Aux 1 settings: output=none, add a Sample Delay
Send Aux 1 to Aux 2
Aux 2 settings: output=none
Insert ducking compressor onto desired track, Side Chain to Aux 2
On compressor, switch the sidechain to "listen" and use the Sample Delay on Aux 1 to sync both clicks (original source kick and the one that passes through the sidechain path)
Repeat later in the project, the latency will be different as we add plug-ins
Don't forget to check the sync before rendering the final mix
TIP: You can adjust the delay to feed the sidechain kick with few ms earlier, so the sound "pre"ducks - (He says "to be honest even if Apple will correct this, I will use the same method, I find this tip pretty awesome in getting a nice, bouncy, ducking." He usually make a group of 16 busses just for these chains.
7. TRY USING MIDI AS A GHOST TRIGGER
Set up the Ghost Trigger (as described by
). Create a new software instrument track (this will not be heard, only read as a trigger for a compressor). Select Klopfgeist (Instrument > Utility > Klopfgeist) as the instrument because it uses almost no CPU. Add in MIDI notes (by drawing or copying from original MIDI) where you want the triggers to be (i.e. match the kick drum pattern). Change Output to a Bus. On chosen Bus, change Output to No Output. Add a Logic stock compressor to a track you want to trigger and select the chosen Bus as the side chain Input. Adjust parameters to taste. Set the delay of the ghost trigger to a positive value in the Inspector so it aligns again (as described by viewtopic.php?t=143422). This works because the sound coming through the Side Chain input is correct in the first place, it's just the compressor that gets triggered too early. Bonus: In addition to general Side Chain issues, can also be a way to automate a side chain. (i.e. If going for a pumping effect, the compressor is only triggered when there’s a MIDI note. If you want to not have the pumping effect for a section, delete MIDI notes.)