ARP Quadra Synthesizer "Keyboard Electronics" Circuit Board PCB PN/ASSY-722021

Description

ARP Quadra 61-Key Analog Synthesizer 1978
KEYBOARD ELECTRONICS CIRCUIT BOARD
ASSY-7220201 PCB
***EXCELLENT CONDITION***
***NO SIGNS OF DAMAGE***
***30V OP AMP HAS BEEN REPLACED, ADDED SOCKET***
***LOOKS LIKE IT HAS BEEN RECAPPED***
https://www.ti.com/product/MC1458
ITS VINTAGE!
https://www.vintagesynth.com/arp/quadra.php
"The Quadra is pretty much a hybrid version of ARP's Omni II and Solus synths. It's a four-section synthesizer consisting of a Bass synth, Poly synth, Lead synth, and String synth. It is quite good at emulating each of these sounds and can function in any of its four modes at a time with the ability of layering the different sections! Sounds you create in any of the four sections are instantly recalled from memory by the push of a button! There are 16 program patches for storing your sounds. Other major features are the incredible phase shifter, tons of balanced audio outputs for each section, dual portamento controls and a superior arpeggiator...that's pretty good for 1978! On the downside, it has a fragile mylar front panel, very limited programability and a weird feature that autotunes the keys to play weird intervals.
The Bass synth section is monophonic and can be programmed to occupy the lower two octaves of the Quadra's 5-octave 61-note keyboard. The bass sounds pretty good and has 16' and 8' presets each for Electric and String Bass sections.
The string section is based on the Omni II String synth. It sounds excellent and implements a phase-shift effect that is sort-of like a chorusing effect that thickens its already great string sound. In Polyphonic synth mode there are more effects available such as sample-n-hold and the phase-shifter. String and Poly Synth sections have 8' and 4' Polyphonic Waveform Generators each along with a preset called Hollow Waveform.
In Lead synth mode the Quadra becomes a two voice screamer with aftertouch sensitivity in the upper octaves of the keyboard! It's duophonic (like the Odyssey). Get a bass sequence going, switch over to another section and play along! The Quadra is a synthesizer well suited to live performance use and has been used by 808 State, ELO, Genesis, The Human League, Pink Floyd, New Order, Nick Rhodes (Duran Duran), Joe Zawinul, and film-maker John Carpenter. The 16 patches of memory aren't true memories, they simply recall which parameter sliders are active (and thus need adjusting!) and which are standards settings."
MADE IN USA!
ASSY-7220201 ASSY 7220201
FAB-5417501 A FAB 5417501