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Mar 2, 2023 A look at the famous ARP Quadra from 1978. Huge thank you to Andrew “The Quadra“ Ward for the loan! Download the song (all proceeds to the Alan R Pearlman Foundation): ARP Quadra Playlist: 0:00 Intro Jam 1:17 Talk: The Quadra 1:37 Demo 1: Skeleton Dance 2:47 The Four Sections 4:40 Talk: It’s Very Simple 5:49 Demo 2: Legit Carpentry 6:51 Talk: Memory? 8:08 Demo 3: Band Member 9:05 Talk: That Keyboard 10:51 Demo 4: Fresh Lineup 12:05 Summary 14:06 Feature Track: Make It Happen VERY NERDY DETAILS FOR THOSE WHO CARE: BASS: Name: ELEC BASS Note Count: Monophonic / Lowest C to the B 23-semitones above / low note priority Settings: 16’ and 8’, fine tuning and octave select Contouring: Resonance and Decay Name: STRINGS BASS Note Count: Monophonic / Lowest C to the B 23-semitones above / low note priority Settings: 16’ and 8’, volume slider Contouring: Affected by the attack and release controls in the adjacent Strings section Name: STRINGS Note Count: Polyphonic and paraphonic / Second C to the highest C / all notes can sound Settings: 8’ and 4’, hollow waveform (switches to pulse from sawtooth) Contouring: Attack and Release FX: Chorus Circuit Name: POLY SYNTHESIZER Note Count: Polyphonic and paraphonic / Second C to the highest C / all notes can sound Settings: 8’ and 4’, hollow waveform affects it too Contouring: Cutoff and Resonance, VCF control from ADSR envelope or LFO (found higher up), VCA affected by ADSR also Name: LEAD SYNTHESIZER: Note Count: Monophonic or duophonic (and paraphonic) with “Two Voice On“ engaged / Third C to highest C or full keyboard if bass disengaged (also can extend the range greatly by using the “Interval Write“ function) Features: x2 VCOs with independent tuning (about 1.5 semitones in either direction) and VCO 2 can be disengaged. The available waveforms are sawtooth, 10% pulse wave or 50% pulse wave and there is also a pulse width modulation switch, which is controlled by the Lead Synthesizer envelope generator. The LFO can be applied to the oscillator pitch for vibrato and there is a trill function (with speed control), the interval of which can be changed using the “Interval Write“ function. There is a footswitch flat or hold switch which relates to the pedal section below. The lowpass filter has cutoff and resonance controls and it can be contoured by the Lead Synthesizer ADSR envelope, the controls of which are to the right. The sustain level does not have a slider, instead, it has a switch to toggle “Sustain Low“. The two notes have independent portamento controls in the bottom left and the master trigger mode can be set here too. In the top right are the aftertouch settings (volume/brilliance or pitch bend) as well as a “sequencer“ which is an arpeggiator for the Lead Synthesizer. It can run up or up/down and frustratingly, it has no hold function. Its tempo is dictated by the trill speed. PHASE SHIFTER/OUTPUT MIXER: Each section has its own volume slider and there is also a master volume slider. By default, the Bass and Lead come out of both the left and right channels and the Poly and Strings come out of the left and right channels respectively. There is then a 12-stage stereo phase shifter that can be engaged for any or all of the sections at once. The phase shifter has a resonance control and its frequency can be a dedicated LFO which has a “Sweep Speed“ control, a pedal (more on that below), a sample and hold circuit that derives voltages from VCO 2 in the Lead Synthesizer section, or the Lead Synthesizer envelope generator. The latter controls can be simultaneously in use, by the “Sweep“ can only be used on its own. Finally there is an external audio input, but frustratingly, this doesn’t run through the phase shifter! OTHER: REAR CONTROLS: Stereo Out (Left and Right Mono) Mono Out with High/Low switch (1/4“ Mono or XLR) Quad Out (Four Mono Section Outs) Mixer In (Mono External Audio In) Lead Synth VCF Pedal In (Can be hacked for other CV inputs) Poly Phaser Pedal In (Can be hacked for other CV inputs as I did in the intro piece) Volume Pedal In (Can be hacked for other CVs to modulate master amplitude) Poly Sustain Footswitch In Pitch Hold Flat Footswitch In Portamento On/Off Bass CV/Gate In/Out Lead CV/Gate/Trig In/Out with x2 CV outs ________________________________________ ________________________________________ Original:
