User Caution: Centaurus reverb runaway volume increase with Pitch Mix > 80%

yyz67

Fractal Fanatic
Release Notes: "CAUTION: The MATRIX and FEEDBACK positions can cause instability at high values of Pitch Mix and Pitch Feedback. In general Pitch Feedback should be low or zero when using MATRIX or FEEDBACK."

I inadvertently discovered this on Centaurus (and a few others) that turning Pitch Mix above ~80% can cause the reverb volume to continue to grow even with no input signal (but with even a tiny amount of signal in the buffer/delay lines). Increasing pitch feedback to 100% moves the point at which Pitch Mix crosses over from a decaying signal to a growing one to a lower value (~65%).

(Fun to play with tho!)

I don't know if Cliff could algorithmically internally "rescale" the mix% and/or feedback % parameters so that this doesn't happen, but confirming the RN behavior.
 
The runaway volume feature also seems dependent on REVERBERATION Time.

The 20 sec default for Centaurus means it's pretty sensitive to Pitch Mix & FB. Lower times (<10 secs) don't grow even if Pitch Mix is 100% (Pitch FB = 0). For Pitch Mix & FB at 100 requires <8 secs to not grow in volume.

Also be careful with very low splice times (e.g. < 20 ms) as volume can build up really quickly.
 
Last edited:
Back
Top Bottom