Simple math question

Member Posts: 93 Helper
edited December 2022 in Reaktor

I replicated something I've seen on the pure data forum and something is really puzzling me

It's a simple ad envelope with the output going into a sqrt ,( the ad evelope mimicks the pure data line ~object going from--> to over x time )

The ouput of the envelope is fed into a sqrt module which make the linear attack stage rise faster , then using a mul* to increase the range( obviously not used for the right speaker because of huge dc signal)

What I don't get is why there is an obvious downward pitchbend when feeding it into a sine function , while the envelope is clearly rising .

Edit , just noticed a mistake on the screenshot , the green and rex bounding boxes on the waveform view should be swapped , sine =green , envelope =red

• Member Posts: 93 Helper

Edit , I think I found it but not sure

The envelope going rom 0--1 is rising the pitch becase for the sine fuction it doesn' t really matter , iow it runs backwards .

Does that make sense ?

• Member Posts: 93 Helper

Now I'v got it ..( I hope )

The ramp sqrt does phase distortion

I compared it with ( cyclone pure data ) kink~ (phasor into kink~) which adds a variabe breakpoint to the linear ramp of the phasor

First screenshot shows phasor into sqrt~(upper ) and lower phasor into kink~ .

Second screenshot shows both outputs (left sqrt,right kink ) multiplied and into separate cosines .

The cosine when driven by kink ~ is obviously played a higher pitches before the breakpoint ( steeper rise ) and a steady lower pitch .after that ( when using mul*)

The sqrt ~ becasue of the conitinous rise has a fallen pitchbend

Always worked with phase distortion to distort ramps into lookuptables , kind of a surprise its capable of pitchbend

• Member Posts: 665 Guru
edited December 2022

You are feeding it into a trigonometric sine function, not a sine oscillator...

The 'frequency' depends on the steepness of the envelope rather than the direction.

And if you are changing the steepness, the 'frequency' will change

• Member Posts: 93 Helper

I am aware that I fed it into a sine fucntion and not a sine oscillator :) , hence the lack of a frequency input .

I've used it enough for phase modulation ( only possible way in primary by use of ramp+ sine function )

And I also know that the frequency depends of the steepness of the envelope , it was just kind of suprising that a rising envelope gave a pitch bend down effect .