What is the best way to limit an audio signal for ADC input (to 0V - 3.3V) with out disrupting it harmonically? Ideally, I'd like the conditioned signal entering the ADC to be a signal uniformly spanning 0V to 3.3V. That is, I'd like to strip the original signal of its envelope and have a flat envelope at the output. I've spent the better part of a month attempting to get simulations of different VCA circuits to respond to these specifications using variations on the original input signal's envelope as the control signal. I know near-blind trial and error through simulation is not the most elegant way to go about design but I'm early in my EE studies and it's all I have.
Is there a standard scheme for this kind of signal conditioning?
Is designing a circuit, whose response is consistent across the audio band (or a good part of it), which attenuates/amplifies a signal, varying from 0.1Vpp to 6Vpp, to a uniform 3.3Vpp signal with negligible change to the harmonic content (negligible meaning that an FFT would still faithfully report the first several harmonics of the original signal) a realistic goal?