[sdiy] Monosynth features poll

[David G. Dixon]

> 7/ If adding a sub-osc, include a sine output (not just the usual
> square), and a level control, and perhaps a way of rolling its volume
> off as pitch increases. That Sub sine loses it's usefulness as pitch
> rises, sometimes becoming unwanted at the top end of the keyboard.

Is there an easy way to do this?  If so, can you point me to it?
Thanks in advance!

Oh, by the way, you forgot the ring mod!