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Bazille: Unexpected behavior when modding CV signal with itself using multiplex 2018-07-10T20:00:52+00:00 TL;DR: Multiplying signals by themselves using multiplexes should make them more exponential. But once a signal has gone through 3+ rounds of self-multiplication, the result is very different from an exponential version of the original. Why??? ------------------------------------------------------ In DSP land, it seems like most CV signals range from either 0 to 1 or -1 to 1. If such a signal increases linearly, this means that multiplying it by itself should convert it from a linear signal to an exponential one. For instance, consider a macro knob that outputs 0-1 in a linear fashion: When this knob is in the middle it will output a signal of 0.5, but if you multiply the signal by itself, the resulting signal will be at only 0.25 (because 0.5 * 0.5 = 0.25). In Bazille, you can easily do this by sending a CV signal into both the input and mod input of a multiplex. However, I took it to an extreme the other day and the result did not seem to be a straightforward linear-to-exponential conversion. I'd like to know why. I was trying to create a kick drum with a super fast exponential pitch envelope. So I set ENV2's Att/Sus=0 and Dec/Rel=really short, then sent the envelope into a multiplex's input and mod input (as described above). This made the envelope more exponential and snappy. Then I took this "exponentialized" signal from the multplex's output and sent it into a second multiplex+mod, making it still more exponential and snappy. Then I used a third multiplex+mod for even MORE exponential goodness. So far so good.... But then I sent the thrice-exponentialized ENV2 signal into the fourth and final multiplex+mod input, and the output was totally unexpected. Rather than just becoming even more exponential, the envelope shape completely changed. First and most surprising, there was some very noticeable attack, with the pitch rising before falling to sustain, despite ENV2's attack being set to 0. Second, the decay stage was noticeably slower than with the three exponentialized signals that preceded this final one, which is the opposite of what you'd expect if the envelope had become more exponential. Wanting to experiment more, I increased the attack to see what would happen, and it sounded like an entirely new envelope stage had appeared!: the pitch fell (new stage?), then rose (att), then fell again (dec), and THEN hit sustain (sus). As far as I understand it, simple multiplication cannot explain any of these changes to the envelope. Intrigued, I recreated the same routing using a triangle LFO instead of an envelope, and found that the result becomes unpredictable at the same point. Unless I've fundamentally understood the maths behind what happens when you multiply a linear signal by itself, additional layers of self-multiplication should just be more of the same: 0.5^1 = 0.5 0.5^2 = 0.25 0.5^3 = 0.125 0.5^4 = 0.0625 0.5^5 = 0.03125 0.5^6 = 0.015625 etc. But instead, in Bazille it seems that there's some magical threshold of self-multiplication beyond which shit gets wacky. So can someone please explain what is going on? EDIT: Admittedly, the self-multiplication threshold I'm finding in Bazille isn't really (x^4). Instead, it's more like ((((x*x)^2)^2)^2) (which is significantly more extreme) because I'm modding multiplies with already-modded signals, not the pure, unmodded ENV2 output. Maybe this fact is noteworthy? But still, maths is maths, so why is there a threshold at all? themagicalkamja https://www.kvraudio.com/forum/memberlist.php?mode=viewprofile&u=382481

Howard Howard https://www.kvraudio.com/forum/memberlist.php?mode=viewprofile&u=26645: KVRAF
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Post by Howard » Wed Jul 18, 2018 6:47 am

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themagicalkamja wrote:Edit: I do see the equations in the Multiplex section of the Bazille manual.

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