Eventually, even the most impassioned synth lover gets bored of mixing oscillators together. You need a little spice in your sound life. You need Karplus-Strong synthesis.

Commonly associated with physical modeling strings, Karplus-Strong can also be thought of as a flexible feedback system of delayed, filtered noise. Okay, that’s a lot more abstract than imagining fake strings, but I say that for a reason – because it’s a system with lots of component parts, you can use it to create a wide palette of sounds. Some might sound like strings. Some might sound more artificial. Some might sound like percussion. Some might sound downright weird. You get the idea.

And it’s actually one of the best things you can do with a modular rig. (Indeed, if you really want hardware and you’re on a budget, getting the modules that accomplish this is a great start.)

But alas, finding explanations of this that are easy to follow has been something of a chore. So, we must again look to our friends in Moravia, Czech, to humbly and lucidly walk us through the process as no one else can.

That Nikol, she’s the great synthesis guru of our time.

So-called “Patchení Nikol” is back in the latest of the wonderful series put out by Bastl Instruments. (Child of Nikol joins her, too!) And now might be the time to binge watch. (Plus, she’s speaking nice, clear English, too, in case you were afraid of hearing Czech!)

She explains the synthesis concept, then shows you some nicely chosen Eurorack modules for pulling it off.

One advantage of Karplus-Strong’s flexibility is that it works with both digital and analog gear (or any combination), whereas some physical models are digital only.

And if you’re on a budget or need to accomplish the same on the bus, you could easily port this to Reaktor Blocks or Pure Data or something else. That loses the fun of patch cords and physical knobs (though you can certainly assign the latter), but does open up other modulation options — and Pure Data is free, crucial for any of us out of cash. I’d actually been doing some demo patches in these already, so I will take Nikol’s work as inspiration and try to polish them up by next month to share.


Other ideas, or useful demo materials? Got some patch of your own or SuperCollider code or whatnot to share? Comment away!

  • heinrichz

    Great article here! Physical modeling is my favorite synthesis method for producing stunning pseudo-acoustic and other worldly sounds with intense dynamics. If you don’t have the hardware i recommend using Chromaphone, NI Steampipe, Prism and even Kontour, which also maks use of phase modulation, shapers and a combfilter.

  • gustav

    Good tutorial! One thing she misses is that the delay time defines the fundamental frequency of the resulting sound and therefore the perceived pitch. That’s the reason why you need a short delay, it needs to be at least 50 ms (20 hz).

    • Gustavo Bravetti

      I agree and I must add that as the delay time defines the fundamental, a way to modulate the delay time to follow incoming pitch is a must to be able to play melodies. Actually thats for me the hardest part when working with this kind of synthesis on modular environments.

      • Mikhail Myasoedov

        she said in comments that doepfer bbd delays tracks nicely

  • This is comb filtering.

    • Gustavo Bravetti

      Nope, comb is another thing 🙂

  • lala

    attention not the usual noodling! lol
    this is quite funky

    you need really short delay times something between 3 and 25 ms for the pitch …

    • lala

      you can also do this with any free delay plugin that offers short delay times;
      you get the idea I guess

  • wingo shackleford

    I dig her. The baby is a nice touch.

  • Ben Mason

    Great tutorial! For bus types, the Moog Model 15 app works. I reccomend pink noise to the 904A, using separate envelopes to keep the burst shorter than the filter mod. The delay time can be set in 1ms increments, using wet/dry mix to tune the “strike” sound. For the intrepid, I’m sure there’s an external delay you could patch in through audio-bridge.

  • DrüMünkey

    Synth, baby,cool technique, yea yea yea… THOSE SHELVES!! So cool! 🙂