OB-Xa emulation : Synapse Audio Obsession
" Obsession brings the power of a great polyphonic vintage synthesizer to your fingertips. It combines the astute modeling of voltage-controlled oscillators (VCOs), voltage-controlled filter (VCF) and voltage-controlled amplifier (VCA) with a comprehensive individual voice control that has never been done before in this detail."
There are several VST emulations for Oberheim synthesizers such as Arturia OB-Xa V, Sonicprojects OP-X Pro-2, Synapse Obsession , etc. My best pick is the Obsession. I found that this VST synth sounds great and is very responsive to EWI. It can create fat, thick, smooth, and analog-feeling brass sounds. The pad and lead sounds are great as well. I can control filter envelop amount with breath controller (midi cc #2) . It also allow expression midi cc # 11 to control any parameter real time. I feel this completes my VST synth collection including U-he DIVA, REPRO-5, Reverb Machine TAL U-No-Lx, Korg Mono/Poly, Xfer Records Serum and Spectrasonics Omnisphere. Now I am waiting for a DSI OB-06 as a final add-on to my hardware analog synth collection.
The patches are easily tweakable and many patches are available free as well as commercial.