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Old 06-27-2020, 10:13 AM
RTGraham RTGraham is offline
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Join Date: Dec 2017
Location: New York
Posts: 51
Default Re: Can Anyone Verify / Advise? - Plugins / Delay Compensation / Timing / Downbeat

Here are steps to follow to create a test session that demonstrates this.
(I had attempted to reply to this post with a Dropbox link to a ZIP of a session folder, along with a description of that test session, but after two attempts over a 24-hour period that reply still has not shown up, and may be waiting for moderator approval.)

So - the steps to follow:

1) Create a new session. For my test, I set the bit rate to 24 and the sample rate to 48k.

2) Create three new mono audio tracks. For my purposes, I named them “KickGen,” “SnareGen,” and “HatGen.”

3) Insert a Signal Generator plugin on the first track. Leave the waveform on Sine and set the frequency to 50Hz.

4) Insert a Signal Generator plugin on the second track. Set the waveform to Pink Noise.

5) Insert a Signal Generator plugin on the third track. Set the waveform to White Noise.

6) Insert an A.I.R. Filter Gate plugin on the first track. Set the Rate to 1/4 note. Leave the pattern set to Straight. Set Attack to 0%, Hold to 25%, and Release to 50%. Set the Filter Mode to LP, with a Cutoff of -5% and a Res of +5%.
This will cause only quarter-note pulses to come through, resembling a kick drum.
NOTE THAT while A.I.R. Filter Gate will perform this operation even when the transport is not running, the synchronization of the quarter notes will jump once the transport is engaged (in other words, when you press play).
This indicates that A.I.R. Filter Gate is designed to synchronize its timing to the downbeat of a measure, in order to be rhythmically accurate to a session’s grid.

7) Insert an A.I.R. Filter Gate plugin on the second track with the same Gate settings, but set the Rate to 1/2 note, the Filter Mode to BP, the Cutoff to -3%, and the Res to -85%. This will resemble a snare.

8) Insert an A.I.R. Filter Gate plugin on the second track with the same Gate settings, but set the Rate to 1/16 note, the Filter Mode to HP, the Cutoff to +50%, and the Res to -50%. This will resemble a hihat.

9) Start playback to force the filter gate plugins to all synchronize with each other, then stop playback again.

10) Highlight the first four measures of all three tracks, and Commit them. For my test session I chose to consolidate clips and make the source tracks inactive. My track volumes were all at 0.0 so the option to include volume and mute automation was irrelevant.

11) Delete the first and last measure of the resulting audio, as the filter gate plugin sometimes takes a moment to catch up with its own synchronization at the start of audio processing, even on a Commit operation. This will leave two measures of audio on all three tracks, starting at the beginning of Measure 2 and ending at the beginning of Measure 4.

12) Create a stereo Master Fader track. I named mine “SubMaster.” Set its routing to Bus 1-2.

13) Set all three printed audio tracks’ outputs to Bus 1-2.

14) Create a stereo Aux track. I named mine “SubMaster Monitor.” Set its input to Bus 1-2 and its output to your main monitoring hardware outputs. Solo-safe (command-click the Solo button) this track.

15) On the MASTER FADER track (not the Aux track), insert a new A.I.R Filter Gate plugin in the FIFTH insert (Insert E), so as to leave room for additional plugins before it. Leave the Pattern on Straight, set the Attack to 0%, the Hold to 50%, and the Release to 50%, and set the Rate to 1/4 note. Set the Filter Mode to Off.
Make sure looping playback is enabled.
Start the transport, or if the transport was already running, stop and restart it.
You should now hear a rhythmic pattern where the beginning of each quarter note is accurately a full transient. This is the correct behavior.

16) Insert a Maxim plugin on the first insert (Insert A) of the Master Fader track. Leave all settings at the default, but set the Mix to 0 (fully Dry). We are using Maxim simply to force delay compensation, since it is a plugin that induces substantial delay.
Start the transport. The filter gate’s affect on the audio will no longer be properly synchronized to the measure’s downbeat, and instead of hearing clean chopping you will instead hear something resembling flamming because the audio transients no longer line up with the timing of the filter gate’s envelope.
Note that the problematic behavior will still occur even if the plugins are inserted on the Aux track instead of on the Master Fader track.

17) Insert additional Maxim plugins in the other Master Fader inserts before the filter gate, to hear the problem become more evident.

18) If you would like to complicate the behavior, create another Aux track to use for reverb. Insert a Maxim plugin before an A.I.R. Reverb plugin, or else insert any reverb of your choice that requires delay compensation. Create a send from the “snare” audio track to the reverb aux, and set the send’s level to about -12.0dB.

19) If you would like to test how this prints or commits, you can create an audio track with its input also set to Bus 1-2, and record into it in real time. You can also Commit the “SubMaster Monitor” Aux track, and you can create another Master Fader controlling the hardware outs to test how a Bounce behaves.

I'm aware that the timing of A.I.R. Filter Gate has been discussed elsewhere in this forum, but what I'm demonstrating here is not limited to that plugin. I can create the same timing problem with, for example, Sound Toys' Tremolator or xfer's LFOTool. Pretty much anything tempo-sync'd that depends on knowing where in the measure it is. I'm just using the filter gate for demonstration purposes because it should be easily accessible to other users as well.
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