Nonlinear Labs C15 Synthesizer Hands-On Review

In his latest loopop video, host Ziv Eliraz takes an in-depth look at the Nonlinear Labs C15 synthesizer.

The Nonlinear Labs C15 has been a somewhat polarizing synth since it was introduced, because of its focus on being an expressive instrument. For example, it has no LFOs to automatically modulate sounds, because it’s designed with the idea that you will expressively modulate sounds using your fingers on its dual, full-length ribbons or its unique pitch bender, or using its four pedal inputs.

The top of the keyboard is detachable, so you use the keyboard section for performance and add the top panel for doing deeper programming.

Eliraz digs deep into the synth’s expressive options and its unique sound engine.

Topics covered:

0:00 Intro
1:50 Overview
2:55 Expression
5:25 Interface
8:25 Synth engine
9:00 Osc A & B
11:20 Shapers
12:40 FB mix, Ring Mod
12:20 SVF
15:30 Comb filter
19:15 Output mixer
19:55 Feedback mixer
21:35 Effects
23:40 Envelopes
25:25 Elevate
26:25 Macros
27:50 MIDI hacks
28:20 KeyStep Chords Arp Seq
29:45 Expression ring
30:25 MIDI LFO
31:35 OSC as LFO
31:55 Cool stuff
33:40 Pros, cons
38:00 60 P-sets

For another look at the C15, check out our interview with Nonlinear Labs founder Stephan Schmitt at the 2019 NAMM Show, below. Schmitt gives an introduction to the philosophy behind the C15, and then demonstrates how the keyboard’s expressive capabilities dynamically control its synthesis engine:

For more information on the C15, see the Nonlinear Labs site.

30 thoughts on “Nonlinear Labs C15 Synthesizer Hands-On Review

  1. A very interesting synth, beautifully crafted for sure, by folks who had a unique vision. However, for $4k I would be very hesitant to buy a synth where I feel like I would be asking “why isn’t this included”, or “why did they design it this way” a lot. It was cool that loopop drew the parallel to Kontour. I always felt like that was an underappreciated synth. Very simple in one sense, but you can create some amazingly complex sounds with it.

      1. I thought about the same thing for 2 days, comparing to other options, and today i ordered the Opsix.
        To switch EACH OPERATOR connection between FM, RingMod, Filter, Waveshaping and since OS 2.0 use operators as effects or noise is powerful. Nick’s soniclab video convinced me.

  2. Why add an arpeggiator if your philosophy is user modulation?
    If the users need to provide their own vibrato what on earth is the instrument creating notes for them for?

  3. I’ve programmed over 100 sounds from scratch on the C15. Maybe half of them feature modulation that most people would think comes from an LFO. That’s because LFOs are oscillators, and there are two extremely flexible oscillators on the C15 that can be used to modulate each other, or the comb filter, or the variable-state filters.

    This synth has been misunderstood since launch. It’s also definitely not for everyone – if one were to make a comparison to a Prophet 5, for example, that would indicate the C15 is not for that person. It’s expensive, yes, but if you have a stable income, Nonlinear Labs makes basically any payment plan work and it can be returned at any time. For me, I can’t imagine ever getting rid of it.

  4. The demand for Star-Trek-ish boutique synths seems surprisingly high. I wonder how profitable they are to create? Not many can drop $4k and up, so their total unit-sale numbers will be low. Just curious. Bowen still supports his Solaris, so it can be done well.

    That makes arguing their design points seem downright goofy. This one is missing an element or two for me, but its still an elegant thing… I’ll never even get to demo. I laugh when people argue over the Yamaha CS-80. I got to fiddle with just two of them as a kid. I naturally fell in Synth Luv, but back on Earth, the numbers built are always surprisingly low for Mega-synths. So, um, meh.

    I have a computer that’s filled with about 3/4 of everything synth, so I’m already on Mount Olympus. It makes it easy not to sweat the small stuff.

    1. Today’s high-end boutique synths are the classics of tomorrow.

      There’s obviously a ton of interest in dumbed down synths and synths where they’ve cut corners to keep things cheap. But, like you suggested, there are so many incredible options at the high end, from the Sequential Prophet 5 to the Moog One to the Super 6 to the C15.

      It’s a golden age for synth fans. We’ve got it better than at any time in history. So it’s really puzzling to me how these great synths are so polarizing to some people.

      When Moog introduced the One, it was without a doubt the best polysynth that they’ve ever made and one of the best polysynths ever made. But it seems like half the people can’t get over the price or the idea that there’s an big audience of people that will buy a $6,000 synthesizer.

      And they’re not just mystified that people want to buy synths like the Moog One, but they’re angry about it. They think it’s a scam that boutique companies make super synths, when a company can make a decent polysynth for $1000, They’re angry that ‘rich collectors’ are somehow spoiling the market. And they think that the buyers are getting scammed because Behringer will make it for $99 or you can buy an Arturia soft synth version.

      I’d love to eventually have two or three top of the line synths like this, in addition to the many more affordable ones that I own. I currently have a K2500, which was top of the line in its day, and I got it for under $1000 and yet it has enough depth that I know I can explore it and discover new features and new sounds for as long as I live.

      It just puzzles me how we have the best synth options ever in history and yet so many people don’t see it, they just see things to whine about.

    2. “Not many can drop $4k and up, so their total unit-sale numbers will be low. ”

      A while back, Moog announced that they’d shipped 3000 of the One synths:

      That’s like a minimum of $10 million in sales/year, for one product, which is lot of business for a small company.

      And the Super 6 is doing well enough to justify a sequel. Dave Smith is selling tons of the Prophet 5. The Schmidt guys keep selling out batches of their $25k monster.

      Smart companies will have options at the cheap end for beginners, midrange synths for the mass market and some high-end synths, too. Currently, nobody is doing this better than Korg and Moog. No matter what your budget, they’ve got a great synth to sell you.

    3. I tend to agree about the hight end market. I’m no economist, but it appears that the middle-class is smaller than ever, so there are more folks able to afford expensive instruments than ever (my FB feed explodes with Greg Koch demoing gajillion-dollar custom Les Pauls all day long…”Ooh! It’s sunburst, how unique!” 🙂 but I digress). C15 isn’t for me, but going on about what it doesn’t have kinda misses the point – think of it as a very specific tool that does it’s particular thing really well. Nobody grouses because, “for that kind of bread, that custom shop Les Paul ought to be able to sound like a dobro and a 12-string.”

  5. Would you buy a synth with no dedicated lfos and a single dial to enter values for 4000€, that has midi as add on dongle and no polyphonic aftertouch?
    Hell no, are you kidding? Is it the mid 80s again? ^^

    1. Yes, if i tested it, use it, understood what it is, liked it and have the founds.
      No, if i think i know what is all about by watching some videos, read the specification and looking for what its missing instead of what its got.

      1. I can tell you by one look at the one knob UI that I don’t want that. Been there, done that. 😉
        Its 2022. complex sound engine and no touchscreen, but one knob. It’s a joke. 😉

        1. I’d like to try one. Although it has one knob, my understanding is that it still has muscle memory and you can program it without looking at it, because there’s roughly one button per function. That might be good enough. In fact it might be better than having 200 knobs on a synth with memory, because the knobs would all be showing the wrong values. And way better than a touchscreen — those have no muscle memory and you have to keep looking at the screen.

          1. im rubbing a touchscreen all day long, sure I got muscle memory where things are on the screen, even if “the window” changes. 😉
            its an urban myth that this does not happen.
            and the screen tells me what is going on in context, knobs and buttons do not do that.
            a 4000€ synth that needs an external editor is a fail.

        2. I can play and manipulate the C15 with my eyes closed. Once you understand the instrument, the UI makes a lot of sense.

          1. there are 4 pedals that u want to be able to adjust in context (as a simple example), impossible without the editor. u need to hop from one to the other …
            I dont know if that fits your idea of being practical. ^^

      2. This is definitely something you need to test to understand. I have played on two different occasions, and it is a really nice instrument. Technical specs rarely communicate how an instrument feels to play. Try it if you get the opportunity!

    2. @ lala

      Yeah why appreciate a paint of a ridiculous Spain painter with weird mustache how cant paint a Clock as it should (round) damn those melted watches should worth nothing nowadays?. Is not the brush…is the vision and the talent.

      1. this is non sense. I dont want to drive on a painting to the supermarket …
        you are mixing the brush up with the painting. 😉
        and this brush we are talking about here happens to be particularly odd. 😉

  6. I just saw a review of the C15 by loopop. The design of the synth is refreshing. Its unique and very artistic. It definitely has personality. The two ribbons and four pedals appear to give lots of opportunities for expressive articulations. It makes a statement as a musical instrument. For instrument of this quality 4K is not that bad. You want to see high prices for musical instruments check out the price of a good bass clarinet or bassoon…..

    1. Amen, people that complain about megasynths costing a few thousand dollars need to go price out cellos, reed instruments, etc for a while. Modern synths offer amazing value for money relative to almost any other instrument on the planet.

  7. I generally like the reviews of Loopop, but this time I am a bit disappointed, since it does not comment on the main focus of the synth, which is performing with it.

    Does it really bring something extra to the table for the performing musician? How different is it to play this instrument in comparison to other synths? Is it really more like a traditional instrument (whatever that means)? The review fails to address this topic properly when talking about the synth engine.

    By the way, based on what is shown, I fear the answer is that the synth does not bring much extra.
    I think current MPE controllers are bringing much more to the table.

  8. I have had one for a year, recorded an album with it, now gigging with indie rock band in NYC. I will add that I got mine on the rent-to-own plan which Nonlinear Labs offers interest free to students and working artists – I pay 87 euro a month. This synth literally feels like an acoustic instrument. I’m classically trained (violin was my main instrument) so the bar is very high for me to say that this feels like playing something ultra-expressive and acoustic. There is no way to understand this synth without playing it. Not everyone is looking for this level of playability in a synth. That’s the main purpose of the design, which is clearly stated in all the promo material and that’s your priority, there’s nothing else like it. Like others have pointed out, its incredible cheap compared to acoustic instruments of comparable quality.

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