Full Bucket Music tells us that the Nabla is a VST2.4 software instrument for Microsoft Windows simulating the KORG Delta DL-50 Strings Synthesizer from 1979. Is is written in native C++ code for high performance and low CPU consumption.
Paraphonic Synthesizer and Strings sections
Up to 64 voices polyphony
Flexible pitch/filter modulation by LFO or noise
Tweaks (not to be found in the original Delta):
Double precision audio processing
All parameters can be controlled by MIDI controllers
Plug-in comes in 32 bit and 64 bit versions
Fully compatible with SM Pro Audio's V-Machine™
Pricing and Availability:
Free download. Donations welcome.