env_curve: 2 sometimes produces clicks instead of expected synth sound

[ethancrawford]

I have noticed in certain conditions, (at least observed on my system) that setting env_curve: to 2 produces a clicking noise instead of the expected synth output.
While not having been able to do a thorough investigation yet, a basic example of the problem is:

play 50, env_curve: 2

It also occurs when using different synths. All synths except :pretty_bell, :dull_bell and :tb303 seem to exhibit the same issue.

I dug around a little bit in the synth designs to try to see if I could spot anything that might be different between the synths that exhibit the issue and those that don't, in case that gave me any clues as to the cause of this, but haven't really seen anything tell-tale yet.

I'd be happy to keep investigating if someone had any further suggestions.

[ethancrawford]

Also, if you add attack: [value] or release [value] when env_curve: is 2 then you hear the click.

[ethancrawford]

I'm beginning to think it has something to do with this code, as all of the affected synth designs I've looked at so far all share the use of this fn, and the unaffected synths don't:
https://github.com/samaaron/sonic-pi/blob/master/etc/synthdefs/designs/sonic_pi/synths/core.clj#L50-L74

[samaaron]

Interesting find, thanks for bringing this to my attention :-)