Distortion in Juno patches

[dpwe]

Many of the Juno patches (as loaded with juno_ui.py) are sounding great.

Some, however, take the AMY engine into severe distortion space. We need to track these down to remove the opportunities for whatever nonlinearity they are inducing. The problem patches include:

• 38 = "A57 Thud Wah". High resonance + inverted filter env is wrapping. Then somehow the ChorusII is making it much worse; turning off chorus reduces distortion significantly
• 88 = "B41 Resonant Rise". Another case of high resonance + inverted filter, so a sweep up from below-harmonics at the start. And again Chorus II is badly exacerbating it.
• 111 = "B68 Ow Bass". No chorus, but high resonance + inverted filter pushes the filter to the negative rail all through the note.
• 127 = "B88 Owgan". Sounds fine until release, which clamps at the positive rail until the note is terminated. High resonance again.