Korg saw the writing on the wall for virtual plug-in synthesizers early. While other manufacturers steadfastly held to manufacturing physical instruments, Korg branched off and began creating virtual emulations of its most popular models, including the MS-20, the Wavestation, and the venerable M1 workstation—of which I owned an actual example way back in 1988 when it was released. Like Arturia's iMini, Korg iPolysix ($29.99) is an emulation of a specific analog synthesizer—in this case, the popular six-voice Polysix from 1981, which was the first relatively affordable polyphonic synthesizer. Korg iPolysix brings almost all of the real Polysix's goodness to an iPad near you—and for far less than its original list price.

User Interface and Sound Quality
For this review, I tested Korg iPolysix version 1.1 on a 16GB, Wi-Fi-only Apple iPad 3; Korg recommends an iPad 2 or later, and says it's optimized to work well on an iPad mini. The main interface looks a lot like the original's front panel, albeit in a condensed form.  There's a key difference, though: When you turn a dial, an overlay appears above it in amber that shows the exact value down to two decimal places, which is quite useful and makes precise adjustments easy.

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Tap the lower left lever, and a larger keyboard pops up that lets you adjust the width of the keys and the octave positioning. You can also tap "Kaoss Pad," which switches the instrument keyboard out for a pair of X-Y trackpads similar to what Animoog and iMini offer, plus the ability to choose from 35 types of scales and modes. Under the hood is Korg's electronic circuit modeling technology, most of which is dedicated to emulating a real Polysix. The iPad version adds a velocity controlled high-pass filter and a few other niceties the original synth didn't have. There are also 28 different internal effects.

In practice, iPolysix sounds great. The real one wasn't the world's fattest-sounding analog synth to begin with, but it was certainly versatile and fun to program, and iPolysix captures the feel of the instrument nicely. That said, presets are a little stingy; you get just fifty, and, while many sound great, the overall selection isn't particularly inspired. To be sure, iPolysix is designed for people to get down and dirty with all of the on-screen knobs and buttons, but another 50 or 100 patches would have given new users more jump-off points with which to create their own sounds.

Production Environment and Conclusions
What really makes this app interesting, though, is that you also get more than a Polysix emulation. For starters, you actually get two Polysixes; you can load sounds into two separate instances of the Polysix, and then play or record from both simultaneously. Korg iPolysix also contains a miniature composition environment; in addition to the two synths, you get a six-track drum machine and an eight-channel mixer with virtual VU meters. There's also Polyseq, a step sequencer that's part of each Polysix instance, and is great for electronic-music-style pattern composition. You can string up to 32 patterns together per song, with tap tempo and swing quantization.

In practice, this is a fun environment to compose beats and hash out song ideas, as long as you're thinking electronic music and not, say, a blues band or orchestral film score—which is perfect given iPolysix's target audience.

The latest version 1.1 adds some new features, the biggest of which is Audiobus support, which lets you stack audio from multiple apps, or stream audio from one app to another for recording. The new version also supports virtual MIDI, another between-app synchronization protocol, plus Retina screens and iCloud backup. Finally, online sharing options include Polystage, Korg's SoundCloud-based online platform for sharing and remixing songs with other iPolysix users; it requires a SoundCloud account. You can also export .WAV files, sync up with other WIST (Wireless Sync-Start Technology) apps, and control iPolysix with a USB MIDI keyboard like the Samson Carbon 49.

Korg iPolysix is a great way to get a "real" analog synth in a portable package. While the app is expensive by iPad standards, it's unbelievably cheap when compared to buying a real Polysix off of the used market—not to mention keeping it in tune and in proper working order. It's also a heck of a lot lighter to carry, and that certainly counts for something. If you do want the fattest-sounding synth, you may want to look at Arturia iMini instead, although that app lacks iPolySix's multiple-synth functionality, as well as its step sequencers, mixer, and drum machine.