OB-Xtreme

OB-Xtreme 2.0 is a full remake of 2014 version 1.0, while V1 was a simpler take on an OB voice card architecture, V2 is more closely related to original OB designs and specs (including features from OB-X, OB-Xa and onward) it is not a direct V1 replacement, nevertheless it got a Legacy mode for Envelope Generators and Filter control so V1 sounds can be reproduced or made.

in a nutshell OB-Xtreme can act as an 8 voice polyphonic, 8 voice unison mono or true (one voice) mono, a FAT mode engages the unison while also providing polyphonic unison, that means 8x8 voices power.
Most OB-X/OB-Xa functions are provided, including SAW, PULSE, TRI oscillators shapes and the peculiar SAW+PULSE which can produce an interesting +1 OCT harmonic depending on the pulse width setting.
the 2Pole filter is based on the OB-X and the 4Pole is based on the CEM3320 implementation, the 2pole has that classic SVF linear "singing" resonance across the bandwidth while the 4pole will resonate less at lower cutoff values (a bit Moog like), a band-pass output is also provided in 2pole mode while 4pole have an optional volume loss compensation.
The Xtreme factor is the main control over the emulated OTA induced distortion, one chip in particular the CA3080 was used a lot at different places in the circuit (although less and less over the OB synths evolution). OB-Xtreme gives some control over that, you can push them way beyond the original specs or stay at minimum for more traditional behavior, you can also bypass PRE or POST circuits for versatility. The PRE stage will act more on lower notes while the POST stage is linear across the range.

Another feature is the under the hood access so you can control the 8 voice cards voltages across the main parts. The cards variations are an important factor to mimic the analog character, while using a VCM (virtual component modeling) approach, I wanted something effective but not time consuming so I designed some predefined offsets and deviations that you can mix in or scatter across all 8 voices.
You get seven macro sliders: OSC (which doubles on the front panel as the "SPREAD") controlling OSC 1 and 2 tuning offsets, FILT filter envelopes offsets, AMP for amplitude envelope offsets, VCF for VCF deviation, PW for pulse width offsets, PORT for portamento time lag and XMOD for cross-modulation offsets. Additionally you can toggle a real-time small random deviation per note or randomize and scatter deviations around. voltages offsets reflect on the GUI as positive or negative voltages (yellow/blue).

OB-Xtreme 2.0 New Features:

• Cross Platform 64-bit capability (Windows VST3 and Mac AU (Audio Unit).
• 64-bit build using latest OS and IDE(PC Visual Studio and Mac Xcode).
• Updated GUI(graphic Interface) also now using high-res graphics and DPI awareness.
• Rewritten and Refined sound engine.
• 8 voices poly or mono unison with per voice PAN control and global stereo widening control, can also turn into real (one voice) mono or act as polyphonic unison (8x8).
• Most of OB-X/OB-Xa functions added (OSC shapes, X-MOD, F-ENV, SYNC etc) on top of new modulation routing.
• Enhanced oscillators spectrum and filter modes (2Pole/4Pole LowPass and 2Pole BandPass) based on OB 2pole SVF and CEM 3320 24Db, 4Pole can have an optional volume compensation.
• Accurate SAW + PULSE OSC mixing (can produce +1 octave harmonic depending on the pulse width).
• Up to x32 oversampling.
• POST and PRE OTA (CA3080 chip used for VCA, Filter and Output Stage) variable distortion (Xtreme factor) with bypass.
• X8 Voice cards voltage offsets and deviation can now be controlled easily by seven macro controls, optional random propagation and real-time deviation (per note).
• Legacy modes for Filter modulation and EG/VCA shapes to match V1 sounds and behavior if needed, the default envelope/VCA behavior is the CEM3310/CA3080 combo (Linear VCA and exponential envelopes) while the legacy mode can be used for more snappy sounds (using an ultra exp VCA response).
• Vibrato LFO, original LFO + additional LFO 2, Phase reverse option mode for LFO (card 1,3,5,7) got phase reversed modulations, can also invert keytracking.
• LFOs have gate re-triggering option, SINE, RAMP, PULSE, SAW, TRI, S&H and Noise shapes, LFO2 can be BPM synced or set as a one-shot envelope.
• LFO can be set to single: one LFO on the main board for all voice cards or to multi: one LFO per card.
• Optional OB-X 6bit resolution on the Filter Cutoff knob scanning.
• Sustain pedal can act normally or use the OB Mode (sustain like piano) controllable Envelope Release offset.
• (Mac) Introducing new Mac Signed and Notarized Installers.
• Basic internal preset browser with main categories.
• OB-X (light mode) or OB-Xa (dark mode) changeable skins.