Build and shape: 9/10
The design feels very solid. Not too heavy, not too light. Buttons feel nice and clicky, and light up when pressed, for a very cool effect. Keys feel really nice. Over-all it just feels like a very high-quality musical instrument, not some plasticky piece of crap like most things these days. Only issue I saw was that one of the keys, if pressed from high up on the key, was not very smooth in its action, but this did not affect normal playing. I've heard the pegs can come loose but I got mine from the more recent production run, after a 4 month backorder delay. So I'm hoping that the pegs have been redesigned on these more recently released ones. The shape of the body, and balance of the instrument feels great.
Ergonomics and usability: 5/10
In terms of usability regarding the positioning of buttons and controls, I really think the RK-100S could be vastly improved with a redesign to address certain issues. A firmware update could also help a lot, which I will explain below.
Good Stuff
First the good stuff: the easily assignable favorites buttons are very cool. The smallish mini-keys take getting used to, but are not a deal-breaker, and it lets you have more keys in a smaller instrument, which is not necessarily a bad thing. When playing with one hand, everything feels like it should, and it's cool to be able to use the "filter" or "pitch" buttons on the neck as a sustain pedal.
Awkwardness of using the Long Ribbon
You cannot use the long ribbon with your off-hand because the hand you're playing the keys with will block part of the ribbon, and you obviously can't play it with the hand you're playing the keys with unless you use your thumb for this, which is very awkward and even painful. It would have made a lot more sense had they put the long ribbon along the edge above the keys, rather than below, so that you could tap or swipe its full range with your off-hand, or hit it with any of your four fingers as you play.
But the main awkwardness of this keyboard's whole design becomes obvious when you try to actually use the "filter" mode of the long ribbon controller.
For example lets say you are playing a little melody with your right hand, and you want to change the tone of the sound by using the Filter mode of the long ribbon controller. Well, now you have to hold down the Filter button on the neck using your left hand, and then run a finger up and down the long ribbon controller. If you had a third arm and a third hand, this would be possible. Unfortunately it's not possible.
The awkward thing that you must do to use the long ribbon controller is to either:
a) hold the filter button down with the left hand, which engages a sustain-pedal effect, and then use the long ribbon controller to change the filter effect on the remaining sound that is left after you finish playing with your right hand and move up and down the ribbon; or
b) press Shift+Filter before playing a song, which engages a mode where the Filter button will be latched always, meaning the long ribbon is permanently in Filter mode and the sustain pedal is always on, freeing up your left hand.
Both of these options a) and b) suck! a) sucks because you have to STOP playing with your right hand to use the long ribbon, and I don't want to STOP. b) sucks because I hate playing with the sustain pedal always down, as it muddies up the sound, and it's awkward to use the long ribbon with the left hand while playing with the right hand, because the right hand blocks the left hand from being able to touch any part of the long ribbon to the right of the right hand without crossing your arms and contorting yourself. It's awkward to even try to explain why it's awkward! Further b) sucks because you cannot press Shift+Filter without stopping playing with your right hand, because the Shift button is on the main body, so you must press it with your right hand, while the Filter button is on the neck, and must be pressed with the left.
As it stands, the best you can do is press and hold Filter after finishing a riff before letting go of the last key(s), then while holding Filter, using your right hand, modulate the sound starting from the far left of the long ribbon (because if you start in the middle, then it starts the filter mod abruptly in the middle of the range, as opposed to starting at the zero of the mod range).
I would also like to see the long strip start any filter modulation at zero no matter where you tap it, and then have the amount of modulation go up no matter what direction you slide from there (ironically, this is basically how pitch modulation already works, except pitch modulation goes +/- where I would have the filter modulation always go +, since it has to start from zero for the transition to be invisible, and it can't go negative without redoing the whole system).
Shift Key
This bad placement of the Shift key is the main flaw of this keyboard's design IMHO. They could fix it with a simple firmware update to make double-tapping Filter or Pitch buttons engage a latch, and further, make sustain inactive while Filter is latched. Really, sustain should have been its own separate button, which could also be latched with a double-tap. Especially since there's no way to attach a standard sustain pedal to this keyboard, it seems like a bad solution to make other useful buttons double as the sustain pedal!
Awkwardness of the Neck Controls
Further I do not understand the purpose of putting the short ribbon controller and octave controls only on the neck, where they cannot be accessed if you are playing the instrument with two hands. (For that matter I don't even know why there is a neck in the first place, other than to make it "look like a guitar", even though there is nothing at all useful about that, other than having a phallic symbol sticking out of your keyboard and putting half of the useful controls farther away from your hand's natural positions.) They should have put duplicate buttons and strips onto the main body for everything that's on the neck, so when you're playing it with two hands, you could still do all that stuff. For example if you're playing with two hands, you can't use the short ribbon, nor the Pitch or Filter buttons for the long ribbon, nor the octave buttons.
If the neck had more than one short ribbon it would make sense to monopolize your whole left hand with it, but just having a single axis of control take up your entire left hand is just dumb. My favorite MIDI controller is the Alesis Photon, where a three-axis optical controller allows your left hand to control three different MIDI parameters simultaneously, which can be very expressive and awesome indeed. Korg could have done something like that here, had they put a simple thumb joystick (like from an XBOX controller) or a pressure-sensitive X-Y pad. Anything but just a basic strip!! Give me a break.
Given how great their iOS apps are, IMHO they should have put an iPhone/iPad holder in the neck, so you could use the Korg iOS apps without having to have your iPad duct-taped to the keyboard. Just a thought!
Annoying Sound Switch
To change patches you flip a metal switch up or down. Well, that's just weird. I've never once seen such a thing before. In pictures of the device I was hoping this would be an X-Y joystick for controlling sound modulation or something cool like fading between patches (alá the original Wavestation), but no, it's just a +1 or -1 increment switch for finding a patch. Holding down shift you can also change which favorites bank you're in. Given that there are 200 patches, it can take awhile to get through all of them.
Sound: 6/10
The sound engine is straight from the Microkorg XL, so if you're happy with that analog modeling, then great, but I've never been the biggest fan of that sound. I wish they had made some improvements to the sound engine or done something more modular like Roland's plug-outs.
The synthesis engine is based around two voices which can each have two oscillators, two LFOs, two filters, and standard ADSR envelopes for various stuff. The signal path is customizable with respect to the filters (parallel/serial/etc.) and each voice has a shaper that you can tack onto the end. The behavior of the long and short ribbons can be customized to a degree. The short ribbon is very useful and can act like a mod wheel or pitch-bend wheel, and you can customize those aspects just like on any other keyboard, by assigning the mod to just about any parameter in the synthesis engine, like cutoff frequency, LFO frequency, etc.
The built-in patches mostly suck. In almost all of them, vibrato is assigned to the short ribbon in mod mode. I freaking hate vibrato! I never ever use it. Whoever designed these patches is either in love with vibrato, or they have a major vendetta against people don't… ugh. If you want to change it to something useful like filter cutoff frequency, this requires using the Mac/PC software, which is a huge pain (as I will talk about in the next section).
There are a few cool built-in patches but this keyboard is stuck in that no-man's land where it does not have any great-sounding samples but its analog modeling is very digital-sounding. It's a step up from your typical cheapo Casio or Yamaha keyboard from the early 90s, but I can't see it replacing any of my analog-modelling virtual instruments or iPhone/iPad apps (like Korg's own iMS20 and iPolysix, which I use ALL the time).
And that's really sad and disappointing to me, because the main reason I bought the RK100S was to hopefully escape from having to use VIs. I was hoping this synth engine would even be better than the iMS20 or iPolysix, but it turns out that no, it's not. It's not bad but it's not a replacement for serious tools like those. And that's just kind of sad, since Korg themselves are who made those apps. Why can't they put the Legacy Collection capabilities into a keytar like this? Sigh.
Still, you can make some pretty nice sounds with this thing, and I'm sure that you could use it for live gigs in a band, etc. But I was hoping that it would allow me to get rid of my complicated rig for live shows and just bring one instrument. Maybe I'll change my mind after playing with it a bit more, but so far I can't see that happening.
Software & Technology: 4/10
There is a proprietary USB MIDI driver you can download from Korg. Works fine. That's a good thing if you want to use this as a controller for VIs and such, because based on the lackluster sound and even worse software (see below), sadly, that's all you will likely use it for.
Customizing patches is done through a proprietary Korg app that runs on Mac or Windows. I have a Mac and I honestly hated using this app. The UI is awful. The fonts are tiny on my screen and it looks like it was designed to run on a PC from 2001 at a native resolution of 800x600. On my 15" MacBook Pro's super-high-rez screen, the window for this app is about three inches across, and the fonts are so small I could barely read them. The controls are all microscopic and many of the things that should be sliders or knobs on screen are, instead, just a number that you click on and slide around to change it. My eyes seriously hurt after using it for very long. I ended up having to decrease my screen resolution to find it usable at all. (There is no iOS or Android app to customize patches. This really made me sad.)
After turning my screen resolution down to where I could actually use it, the software was utilitarian at best. I was able to open a patch, edit it, then save it back to the keyboard. I'm not sure why but the patch on the keyboard reset itself back to the factory default after I changed patches and went back to it.
The keyboard does not support Bluetooth for audio nor for MIDI, which I was also sad. There is no accelerometer or motion/orientation sensor inside that could act as a mod control, which would have really been nice, given that it's a keytar. It feels like this keyboard could have come out in 2002 and nobody would have been impressed with the technology. Who knows how long ago they designed it?
What would really be awesome would be aftertouch and/or keys that each had a touch-strip on them, so you could slide your fingers up and down on the keys to modulate each note individually. Of course that would probably cost too much, but sigh.
Features: 8/10
Aside from these complaints I felt that this keyboard has a lot of great features. It's a very limiting design with lots of seemingly bad design choices, but if you accept it for what it is, there certainly are a ton of features. And the features do work.
I mean, it's awesome to have a battery-powered keyboard with a decent built-in sound engine that can be worn and attached directly to an amp. Having vocoder capability is also very cool, and that might end up being the killer app of this keyboard, given the fact that its not very well optimized to be played as a traditional keyboard and its controls are so awkwardly placed for that purpose. If you're singing and you don't need two hands to play a keyboard song, then the problems of sustain being held is not a big deal.
The patches being fully customizable via software is another really nice feature. I didn't like the version 1.0 of the software, but the fact is, it DOES have this feature, and it DOES work, and that's still better than NOT having this feature.
There is also a really cool feature that lets you check remaining battery life, which gets displayed on the light-up favorites buttons. This is a VERY useful feature, one that I'd consider mandatory for gigging.
I really liked the ability to plug stereo headphones into the same port that's used for mono output. The port auto-detects if it's stereo or mono. that's cool.
I liked the built-in arpeggiator that you can customize on the fly and play in Latch mode. This is probably the saving grace of the RK100S, given the fact that you can't really play the keys and use the long ribbon at the same time. With the arpeggiator latched down, now you can take full advantage of the ribbon controller. Give the fact that they dedicated two whole buttons to the arpeggiator (Tap and Arpeggiator), and the long ribbon is really only useful with the arp active, I suspect that Korg intends you to use the arpeggiator heavily. Too bad the arp is only 8 notes, then.
I would have much preferred if the keyboard had a small bit of built-in memory that let you create on-the-fly loops of a riff, Ableton-style, instead of a simple 8-note arpeggiator. But it is what it is.
Overall: 7/10
It's a fun instrument and but if you buy one, you must accept that this instrument is its own peculiar animal. It's not like playing anything else I've ever played, and the limitations of the design force you to play in a manner that feels very limiting. Sometimes, limitations enhance creativity by giving you a reason to do things a way that you normally wouldn't, and force you to play a different style. Whether or not the RK100S turns out to be a creativity-enhancing tool that forces you to think outside the box, or whether it ends up just being an exercise in frustration, likely depends on the attitude and creativity of the musician. Either way, they could've made it more broadly appealing and useful with some improvements. I feel that with a redesign (perhaps an RK-150?) this instrument could really be made into something amazing and indispensable. But as it stands I think it will likely end up in the "neat toy" category for most people (as opposed to "serious instrument"). For a $700 keyboard it's a bit too much on the limiting side to really rank too highly IMHO. At this price I'd rather pay a bit more and get a bit more, since we're not really talking the budget category here. This makes more sense as a second keyboard you wear while playing your main keyboard, and I doubt Korg would want to design something that made the Kronos obsolete
Personally my dream instrument would be if they took the RK100S, made it with a carbon fiber skeleton instead of a wooden solid-body (think Skelletron guitar), got rid of the guitar-like "neck", lengthened it to 49 keys, added bluetooth MIDI, more controllers, XYZ accelerometer input, top-of-keys long ribbon, aftertouch, iPad slot, lithium-polymer batteries with a 12-hour life, and optional attachable lithium-polymer powered speakers
Of course that would be the RK-3000 to be released in the year 2019 for $3000. Anyway i digress.
