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Gain Envelope Anomalies

Question asked by PeterTheRed on Nov 6, 2014
Latest reply on Nov 12, 2014 by mmmike

A question / bug  report:  The 'Endless Loop Generic Gain Envelope' function in Sigma Studio seems to have some 'undocumented features.' 


1) One would think that a setting of 0dB in the gain envelope GUI would produce no boost or attenuation.  However, with the envelope set to 0dB gain, I'm measuring 32 dB attenuation!

 

2) Changes to the envelope do not always take effect until the project is re-compiled and downloaded, despite the status indicator remaining in 'Active: Downloaded' mode.

 

3) When this block is first instantiated, the default settings include an initial envelope point set to -100 dB.  It appears that the scaling of the envelope has an inverse relationship with the value of this initial point:  If I increase its value to, say, -80dB, then a nominal 0dB setting produces -43dB (an 11 dB reduction compared to the previous value of -32dB).  If I reduce the initial point's value to -120dB, then a nominal 0dB setting now produces -12.5dB gain - a ~20dB increase.

 

Strange, no?

 

I'm running this on an ADAU1452 @ Fs = 96kHz and system clock = 294.912 MHz

 

I've attached a basic test file that exhibits these behaviors

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