Tube Challenge!!

[Haible Juergen]

	>One problem with tubes is that they can't swing all the way to zero
easily.
	>A negative supply helps here. (E.B. used an extra -150V supply in a
few
	>places.)
	>So building logic with "saturating" on-off switches is difficult.

Now if you really want to go retro, build the digital part of the ADSR from
relays ... but honestly, I don't expect a VCF to sound warmer when modulated
by a tube / relay ADSR. Hmm, thinking of it, the relay's hold time might
add some "punch" before the Decay phase starts ... (;->)

JH.