AW: A few thoughts on the wasp clone

[Haible Juergen]

	>Today I completed the construction of a wasp filter clone!
	>Its on a 100x100mm matrix board. I powered it up, and ... 
	>...it immediately worked :->

Congrats !

	>One thing that *should* be added is exponential control
voltage. 
	>The advantage is one could use it as a tracking filter.
	>A little NPN/PNP expo converter will probably work even at
+/-5V, and the 
	>expo current could be added at the Iabc pins, so one has linear
and expo
	>control 
	>as well. I prefer a filter with expo *and* linear cv inputs,
since with an
	>exponential decay EG, the filter sweeps sound better to me with
a linear
	<response 
	<on the filter, since the time that it takes to sweep the filter
from one
	<harmonic 
	>to the other is equal, for basic waveshapes, and the filter is
longer in a
	>frequency 
	>range where it effects the harmonics.

Ok, you could use the expo converter of the original WASP circuit
then. It uses 1/4 of a LM3900 and two pnp transistors, and it has
a linear input (for keyboard scaling from the Wasp's linear f/V
converter),
and an exponential summing node (for ENV modulation and LFO).

JH.