``Virtual Analog'' synthesis is defined as simulating classic analog synthesizers (e.g., Moog, Arp, etc.) using digital methods. At the 1994 NAMM show in Anaheim, the Nord Lead virtual analog synth appeared to be a pretty big hit. It turns out it's not that easy to simulate analog synthesizers well in digital form. For example, it is not obvious how to ``digitize'' the classic four-pole Moog VCF (also known the ``Moog ladder'' after the appearance of its schematic). Even something as basic as a sawtooth oscillator is difficult to do ``right'' in digital form since a simple resetting-ramp approach generates an aliased sawtooth waveform. Using bandlimited interpolation techniques described in , it is straightforward, but relatively expensive, to generate properly bandlimited sampled analog waveforms.