AW: Expo conv. heater (tomg et al.)

[Haible Juergen]

	>The problem is usually not the 3340, but the leaky, 4051/cheap
ceramic disc
	>cap that the synths use
	>as S&H for the CVs.
	>
	>Also, it will depend on the circuit that does the autotuning. What
is
	>"warming up" is not the 3340 but the auto-tune crap.
	>
	>Paul Schreiber

In fact I had a severe problem with my P5 when I bought it that had to do
with
multiplexing the CVs. I have made a long post to AH back then, but in short
it was a TL084 with leaking input, so the MUX capacitor did slightly
discharge
until it was refreshed. But that alone would not have caused a detuned VCO.
At worst, there would have been a slightly "rougher" sound from the MUX
FM-ing the VCO slightly. The explanation I came up with at last was that
the MUX refresh cycle must be of different length in autotune mode than in
normal operation mode. Therefore the autotune was correcting for a wrong
amount of capacitor voltage droop ...
(Replacing the opamp cured the problem at once, but don't ask how long
it took to find the problem !)

But in my diy modular synth, there is no MUX and autotuning stuff. The same
type of external components (polystyrene caps etc.) for both VCOs. One 
3340 is better than the other, nevertheless.

JH.