Permut8 Fun

John Verity2 145 views4 posts
  • John Verity

    I have been enjoying Permut8, exploring it in various ways. I had been feeding it melodies, or basslines - sequences of notes - with some success, and some frustration. I just did something different, though, whose results I liked and thought I would share. (I am using the device with AudioMulch.) I feed it a simple 110Hz sine wave (a low A, that is) and set Instruction 1 to MUL and Instruction 2 to MSK. And then, I just fiddled around with the operands and Feedback and Filter and Clock Freq. and made some very interesting and varied sounds. Hard to describe them, but there many pleasing combinations. Sometimes the device creates chords and arpeggios, which is a delight. And some cool rhythms. In short, something from essentially nothing! Next, I am going to mess up that sine wave with added distortion and see what that gets me.

    Anyway, all good fun and confirms my experience that the only way to tame this beast is to feed it and fiddle it -- just try stuff and see what happens, take notes, store intersting settins as presets, etc. I's not so easy always to understand why it does what it does, what the math or logic is, but I slowly am getting an intuitive feel for it. I was discouraged at first -- it all seemed so random and prone to making harsh noise -- but not so much anymore. There are just so many combinations and configurations to try and explore and enjoy. And my ear is getting expanded, too.

    I am surprised, I must say, that there has not been more discussion of this plug-in here. How are others using it? What kinds of sounds are you running through it - drum/percussion, notes, tones, noise? (Oh yeah, I originally had fed it some white noise and that, too, yielded pleasing results.)

    Another thing: I wonder if anyone knows of some good explanations of delay lines and their general design and theory and workings. I am very curious to learn more about what's going on inside.

  • Magnus Lidström

    Thanks for sharing. I too find most success when I feed simple and clean sounds to Permut8. During development I mainly used it with MicroTonic, but I have ended up applying it to almost everything, if only to achieve some saturation and compression with the "analogue section". But AND, MUL and MSK are probably my favorite operands for more "creative" use.

    Delay lines are very simple constructs. Consider an analogue tape delay. You have a record head that records the input to physical tape. The tape travels some distance and the recorded sound is then picked up by the playhead after a certain time. The very first "digital" delays worked through similar principles where audio is fed into a chain of analogue(!) memory cells. For each clock cycle all audio data was shifted to the next cell in the chain until it reached the output on the other end. These delays were called "bucket brigade" delays since they remind you of how people can form a chain for passing water buckets to extinguish fires.

    This technique could be implemented in software as well, but it would be a huge waste of CPU cycles. E.g., on a delay line of 30000 samples you would need to perform 30000 move instructions for every input sample. Instead we use a circular buffer, i.e. we view a piece of memory as laid out in a circle where there is no beginning or end. Now we let the write and read pointers run around this circle. If we compare this to the tape delay, we move the record and playback heads around the tape, instead of moving the tape. The result is the same, but requiring just a few CPU cycles per sample regardless of how long the delay line is.

    There are two different ways of changing the length of a delay, regardless of which of the aforementioned designs we are talking about. Either you change the effective length of the delay line. In this case it is enough to change the distance between read and write pointers / heads. Alternative #2 is to change the speed / rate with which the delay line "rotates". Nearly 100% of existing software delays change the length as this is cheaper on the CPU, doesn't affect audio quality and is much easier to implement. Permut8 allows you to use both methods but it is focused on changing speed. E.g. when you tempo-sync the delay in Permut8 it adjusts the clock frequency, not the delay line length.

  • Jason Anderson

    I love to set the input low and get that verrrrry nice hiss out of it. I am HP-ing the Output a lot and just snagging a bit of the original effected material with the nice warm harmonics of the noise. The noise is so soft and warm and sits just right, behind most source signal (mixed low). It's very non-intrusive and doesn't take away attention from what the buffer effects are doing. It doesn't degrade the quality of the effected output either and it plays very nicely with a vintage compressor emulations (that tend to add their own kind of warming noise) on the end of a fx chain containing Pm8. Really a fantastic, smart toy. I am finding that I am throwing this on a lot of different source signals for various reasons. It's also verry nice for getting a certain (custom) wideness in sound from some tracks.

    And the new beatrick firmware is great. I'm using it on rhythmic loops AND background pads/beds etc for just a bit of rhythmic character. I am mixing it very low behind the loops just to enhance the loops with buffer effects from beattrick. A great toy within a great toy. Thanks for that one

  • Jonah Sprout

    For "pure" sounds I like to use 2 copies of Permut8 in a feedback loop! It's easy to do in AudioMulch. The built in limiter in Permut8 really helps, but I stick another one after it for good measure. :)

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