Aurora Polaris – Model 2AP

Aurora Polaris  Model 2AP

Duophonic synth voice

• East Coast style voice architecture
• West Coast modulation routing and audio/CV standard

Oscilator section 

• 4 waveforms , Saw, Triangle , Pulse and dedicated sub osc with three shapes
• Curtis style 3340 HYB core with PWM drift compensation
• VCA for each wave form to allow wave blending
• Local mixer with optical clipping stage
• Local pitch, fine tune and octave switch
• Pitch compatible with Buchla or Euro levels 0.9 1.3V
• PWM CV with attenuator.
• Switchable Modulation output featuring 4 wave forms
• Multi Sync input with level adjust
• FM input with level adjustment, normalled to adjacent VCO
• FM cascading and looping around

LFO and Mixer section 

• 3 OSC mixer with adjustable gain and optical clipping stage
• Level booster 3x
• Collective pitch with 5 octaves range level indicator
• CV input for all three oscillators 

• Through zero LFO with 8 different wave forms
• 8 synced LFO outputs with attenuator
• Frequency control from minutes up to 150hz
• CV control that freezes or doubles at 10V
• Clock input that transforms the frequency into a multiplier
• Phase offset 0-180 degree
• Phase Spread switch with 1:8 sub harmonics

Filter Section 

Two rich multimode filters

• Clean 2-pole (12dB/octave) state-variable design.
• CV-controlled filter response, continuously variable between low-pass, band-pass and high-pass.
• CV inputs with attenuverters for cutoff and resonance.
• Attenuated frequency CV input, calibrated for 1.2V/Octave tracking.
• Self-oscillation after 3 o’clock across the audio range, extending into very low frequencies, with constant high amplitude.

Routing possibilities

• Continuously variable (and CV-controlled) routing from single over parallel to series filter action on the MIX out
• With a signal patched into filter 2’s audio input, the routing knob and CV act as a crossfader.
• Switchable Filter 2’s cutoff follows filter 1’s cutoff relatively.

Two essential overdrive circuits

• A CV-controlled overdrive stage precedes each of the two filters on the input side and bites at 5V
• Overdrive response continuously adjustable between soft-clipping and 2-stage wavefolding.
• Additional optical clipping at the two single outputs which starts around 3V

Envelope section

Three individual ADSR envelopes, two of them with CV control

• Gate (hold) and Trigger (free) modes switches
• ADSR, Gated Looping, and LFO Looping modes
• Exponential and Linear Envelopes
• Normal and inverted envelope modes
• 0.003 sec to 30 seconds long envelopes. 
• LFO frequencies up to 300Hz
• Time CV for envelope/LFO modulation
• Level CV for voltage-controlled envelope depth
• Logarithmic time control response over 1:10,000 range
• Audio out versions of the envelope signal with 1V Peak-to-Peak Voltage

VCA section 

• Dual logarithmic VCAs 0-10V CV +-5V audio
• Internal or external sound processing driven by the ENV
• Normalled to the filter L and R outputs