MOTM

>>I'm not sure if you're asking about the rectifier or the envelope
follower,
so I'll just answer both. Just feed the same signal into both the X and Y
inputs on the ring mod and you'll get a rectified signal out since when the
signal is positive, the two positives multiply to give you a positive out,
and when the signal goes negative, the two negatives multiply and also give
you a positive output.<<

That doesn't sound right. Squaring a signal (i.e. multiplying it by itself)
doesn't rectify it, in the general case. Consider a sine wave as an input
signal. There is a trigonometric identity as follows:

sin^2(x) = 1/2 (1 - cos(2x))

for all values of x [where "^2" represents raising to the second power in
ASCII]. A cosine wave is merely a sine wave shifted ninety degrees, so your
output is a sine wave of twice the frequency (because of the 2 in front of
the x)and half the amplitude (because of the 1/2 at the beginning) of the
input, with positive-only DC bias (because of the subtraction from 1).
That's not a rectified sine wave.

--Adam