The Cherry Audio Quadra is a super-accurate and immensely improved emulation of the ARP Quadra synthesizer, originally released in 1978. It’s something of a unicorn instrument in that they’re rare, not only because ARP didn’t produce a lot of them, but also because many have been scrapped over the years as a result of their inherent unreliability. That said, the Quadra has developed something of a cult following because they were frequently used by Genesis keyboardist Tony Banks, and the late jazz legend, Joe Zawinul. And Quadras look super cool, in a here-come-the-neon-80s kind of way. (For the trainspotters, you can also find a Quadra wedged between Mickey Thomas's mustache and acres of leather in Jefferson Starship's impressively corny "Find Your Way Back" video.)

The Quadra was conceived at a time when ARP was on the verge of bankruptcy, large due to the Avatar, a not-ready-for-prime-time and thus, poorly selling guitar synth. Though ARP made their name on monophonic synths and poly “string” synth instruments, it was clear that polyphonic instruments with instantly recallable patch storage were the way of the future, as illustrated by the wildly successful Sequential Circuits Prophet-5. But instead of putting their noses to the grindstone and developing an instrument that could go head-to-head with the Prophet-5, ARP took the cheap/easy way out and essentially combined a few existing instruments in one box - the Omni II, a glorified string ensemble, the Solus dual-oscillator monosynth, and a rudimentary bass synth. These were (sort of) controlled by an underpowered 8048 microprocessor. We say “sort of,” because its primary function was to manage the Quadra’s 16 patch storage locations, but the patch storage implementation is so ill-conceived and poorly executed, it’s hard to imagine how it made it out of R&D*. Adding insult to injury, the colorful flat “touch” buttons that were all the rage in the late-70s and early-80s were prone to not working, the chassis tended to flex, and the keyboard jutted out from the front of the instrument a few inches, making it very easy to break keys. 

While we’re slugging a synth while it’s already down, another issue: The Prophet-5, and other programmable polys that followed soon thereafter were what’s known as “voice assign” instruments - essentially multiple monophonic synths under the hood, controlled by advanced microprocessors. This allowed each note to have its own independent filter and amplitude envelope curve (imagine a bunch of typical “weoooww" synth notes, each producing their own little “weeooowww” cycle as they’re played). Prior to the advent of the computer-controlled voice-assign instruments of the late 70’s, polyphonic synths and string machines were far more primitive, and would typically have just one filter and envelope generator that affected all notes played. This wasn’t too bad for sustained string or organ-type sounds, but the lack of individual note articulation was less than ideal for plucked sounds such as pianos, clavs, or the “weeoooow” sweep described above. The Quadra’s Poly Synth and Strings sections both made use of antiquated “paraphonic” organ/string machine technology, thus, no individually articulated notes. 

So why would anyone in their right mind want this thing? A couple of reasons... to begin with, ARP had the good sense to incorporate a great-sounding phaser, and the Quadra allowed independent routing of the bass, strings, poly synth, or lead synth sections through it. And although the four synth sections weren't stupendous on their own, the ability to use all four at once (in various split or layered iterations) enabled large and unique tones that would be hard to create on other instruments. Did we mention that Quadras look really cool too?

The Super-Good News

Cherry Audio has seriously addressed all the dumb parts, left the great and unique parts, and wildly expanded the Quadra for an experience that blows away the real thing in every conceivable way. Unlike the original, each section is independently assignable to any region of the keyboard for endless splitting and layering flexibility. The highly limited, one-waveform poly synth's oscillator bank is greatly expanded, retaining the original's "spiky" and "hollow" waves, and adding ramp, and pulse wave with pulse-width modulation, immensely expanding its tonal palette. The odd patch storage has been replaced with Cherry Audio’s extensive, unlimited patch browsing system. And not only did we make a killer emulation of the aforementioned onboard phaser effect, we added a stereo chorus/flanger, a syncable echo, and studio-quality reverb, all individually routable for unprecedented effects flexibility. And finally, we've included a multi out version of Quadra that allows individual DAW mixer routing of each of the four sections for individual panning, using third-party effects plug-ins, or routing to separate physical outputs of a multi-output audio interface.

Pre-Purchase Demo Mode

If you haven't purchased the full version of Quadra, it will run in demo mode. All functions will work, but inharmonic tones will occasionally sound (the LED next to Demo in the top toolbar will illuminate when the ugly tones are sounding). We've also added a handy button to make purchasing easy, so you've got no excuse! As you might expect, all this demo nonsense disappears once Quadra is purchased.

Technical Assistance

Cherry Audio's unique online store and automatic updating should make operation a smooth experience, but if you run into any issues or have questions, you can discuss issues online at the Cherry Audio forums at:

https://forums.cherryaudio.com/

... or you can communicate directly with our dour and irritable outgoing and friendly tech support staff at:

https://cherryaudio.kayako.com/

*Fun Facts About The Original Quadra Patch Storage

(You don't need to read this, but it's fun.)

If you’re a synth historian, or just a nerd like us, here’s how the original ARP Quadra “patch storage” system worked (in quotes, because "storage" is a somewhat optimistic description). On a typical vintage-style analog polysynth with patch storage, all movements of knobs or sliders are converted to stepped digital data using an analog-to-digital converter - the resolution is usually high enough that you don’t notice the stepping. This is done for two reasons: 1) it allows digital storage of control positions, and 2) it allows a single control to be multiplexed to control the same parameter of multiple voices. For example, when the cutoff knob on a Prophet-5 is rotated, its movement is first converted to digital data, then routed (aka, "multiplexed" or "mux'd") to simultaneously control the filter cutoff of all five filters at once

As you might imagine, all those steps of digital data, multiplied by the number of knobs or sliders on instrument, plus storing the positions of all switches, adds up to a lot of digital data to store (at least in circa-1978 memory). Because ARP cheaped out on silicon, the computer processor in the Quadra simply wasn’t up to the task of juggling and storing all of this data, so here’s what they did instead:

If you look at a photo of an ARP Quadra, next to the majority of its parameter sliders, you’ll notice a small orange dot. This indicates a factory-defined default control position. When a user “patch” is stored in one of the memory slots, the program memory doesn't store the slider position. Instead, it stores whether each slider is in the factory default "dot" position (i.e., bypassing the slider control with a fixed resistor under the hood) or if the current slider position should be used. The user selects between the factory preset control position or the current slider position by clicking the green and blue buttons beneath the sliders - if the LED above the button is illuminated, the slider is in "user" mode, i.e. current position. If the button/LED is deactivated, the control position defaults to the aforementioned fixed "dot" position, selected at the factory to be generically useful for... we don't know.

Thus, a "patch" consists of the current on/off state of the 40 blue and green buttons, about half of which enable or disable the slider above (some of the buttons are just switches that select octaves, waveforms, etc.).

Now imagine how wildly useless this is, and how you might end up with roughly 2 1/2 usable stored sounds in a live a situation - and that’s only if all the sliders are in the correct positions. It hurts my head to think about, and it should make it pretty clear why the every-parameter-fully-storable Prophet-5 handily clobbered the Quadra in the synth marketplace in the late 70s and early 80s.

It should go without saying that we eliminated every bit of this madness in the Cherry Audio Quadra.

Important Takeaway About Original Quadra Patch Storage

(You should read this.)

In case you skipped the preceding section, about half of the original Quadra's blue and green buttons work in conjunction with the lame-duck patch storage to enable or disable functionality of the sliders above them. Because the Cherry Audio Quadra has our unlimited, super-great patch browser, it completely does away with the switching-slider-functionality-on-and-off business - all of the blue and green buttons perform standard parameter on/off/toggling duty, making the Quadra much easier to operate, and storing patches is super easy as well. Hooray for modern technology!

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