[sdiy] Linearized 2164 VCA Warning

[David G. Dixon]

> OPA2132:
> 
> Its a high-speed op-amp, so I hope your feedback loop was nicely
> compensated, otherwise it could have been oscillating at a few MHz,
> causing the aforementioned heating.

Yeah, that might have been it, although a quick squizz at yon datasheet has
it slewing at 20V/us, which is just 50% faster than that "dirty, filthy,
smelly" opamp, the wretched TL072.

(Sorry, my kids and I have been working through the Monty Python boxed set I
got for Christmas, and I was reminded of the dirty fork in the "restaurant
sketch"...)