All right, I have just checked the issue, it can be reproduced easily, it's not a Tracktion issue.kylen wrote:Here's some more info - I've narrowed the problem down to the single instance of the stereo Dynamics plugin inserted in stereo audio track in Tracktion2 (got rid of the rack and all the surrounding plugs). I don't have Sonar over here so I can't say what happens there.
Here's my simplified test case:
1. Insert a clean audio track (I have pure pink noise, peak=-12db,rms=-22db).
2. Insert an instance of stereo Dynamics processor with these settings:
Envelope Detection: Att=20.9ms, Rel 203.1ms, RMS avg=204ms
Stereo=flip
Lower Curve: Thresh=-40db, Ratio=0.20, Knee=30db
Auto gain=off
Everything else is set to default I think.
3. Tracktion audio setup:
Direct Sound, 48KHz sampling rate, 6912 sample/144.0 ms latency
4. Hit play in Tracktion, a split-second BEFORE the audio begins I hear a pop, then the audio plays normally. If I set the detector attack to 0ms then I don't get the pop. The fact that the impulse hits just befor the audio starts has me thinking about audio buffers and things of that nature so I'm trying some things there.
NOTE: The impulse hits at +13dbm so I think I'm wrong about this being a moderate tick - it's a pretty fast impuls and I can't perceive it as being loud. Turn your audio down first...beware. I'm gonna post this over at the Raw Materials (Tracktion) forum and see if anyone else has seen this.
Here is what happens and what you can do to avoid it:
What happens
With a down ratio close to 0, very low sounds will be amplified a lot. At the beginning of an audio clip with no sound, the amplification is at its maximum (let's say + 160 dB), and when the sound starts, the envelope takes some time to raise (due to long attack time), so the gain takes some time to decrease. That means that you will have +160 dB gain at the very beginning of your sound, which will produce an horrible clip. If you try with 5000 ms attack time, you can hear a very loud noise as soon as the sound starts.
How to avoid it
In order to avoid such a behavior, here is what you need to do:
- decrease the attack time (as you said, with 0 there is no issue, but you can raise it a little bit)
- use a ratio closer to 1 (I have tried with .6 and it's fine, even with 200 ms attack time)
You need to have a good balance between these two settings. The smaller the ratio (close to 0, which means infinite gain at -oo dB), the smaller the attack time. The issue is produced by the fact that your settings are quite extreme. More generally when using down side expansion beware that humming and noise will be amplified a lot. When experimenting with the Dynamics product, I advise you to use the output limiter to avoid too loud output.
BTW it can produce very interesting effects when combined with the output limiter.
Hope this helps.
