Messages

16

preenfm2 and preenfm3 / Re: Non-linear waveshaping on the PreenFM2

« on: February 27, 2018, 03:17:17 AM »

Enclosed is a quick example as a sysex file.

This uses ALG1, op1 set to 0Hz. The mod wheel is mapped to IM1, which will give an example of the timbral change. Also try changing both operators waveshape.

To get classic waveshaping, I would suggest making some user text wavetables of Chebyshev polynomials =>

https://en.wikipedia.org/wiki/Chebyshev_polynomials

https://courses.cs.washington.edu/courses/cse490s/11au/lectures/E-Non-linearSynthesis.pdf

from the pdf =>
Cheby0 = 1
Cheby1 = x
Cheby2 = 2x^2 - 1
Cheby3 = 4x^3 - 3x
Cheby4 = 8x^4 - 8x^2 + 1
Cheby5 = 16x^5 - 20x^3 + 5x
...

Also see this paper for all the classic refs =>
A Tutorial on Non-Linear Distortion or Waveshaping Synthesis
C. Roads
Computer Music Journal
Vol. 3, No. 2 (Jun., 1979), pp. 29-34

can be read online free =>
https://www.jstor.org/stable/3680281?seq=1#page_scan_tab_contents

I found a Puredata patch that calculates Chebyshev Polynomials!
I first tried using the output of the array to quickly get 1024 plot points but it totally failed. The waveform represented in the GUI for the array isn't the same as the output. I did get a really awesome ramp waveform that I'm going to use.

Next, I recorded the each polynomial at 46.87hz to get exactly 1024 samples and the waveforms sound amazing! As you suspected the aliasing is greatly diminished. I'll post user waveform txt files tomorrow. In the meantime poke around the Pd file.

Credit for the Pd file goes to Simon2:
https://forum.pdpatchrepo.info/topic/4083/chebyshev-polynomials

Here's another great explanation of Chebyshev Polynomials just for reference:
http://sites.music.columbia.edu/cmc/MusicAndComputers/chapter4/04_06.php

17

preenfm2 and preenfm3 / Re: Non-linear waveshaping on the PreenFM2

« on: February 26, 2018, 11:17:29 PM »

can you post your preset?

It's pseudo PWM so it still sounds somewhat FM but I think it's believable. I'm using ALG4 to enable two "oscillators" with PWM. Turn OP2 to SQUA to here both at the same time. It's currently off so it's easier to here the PWM effect. ENJOY!

Patch in a nutshell

ALGO4

OP1  OP4
  |       |
OP3  OP2
 
IM1 1.86
IM2 0.00
IM3 1.73
IM4 0.00

Op's
FTyp Keyb for all
OP1 & OP2 = 0.00
OP3 = 1.00
OP4 = 2.00

Matrix
LFO1 2.09 IM1
LFO2 0.67 IM3

LFO1 SIN 0.13 0.00 0.00
LFO2 SIN 0.22 0.00 0.00

18

preenfm2 and preenfm3 / Re: pwm

« on: February 25, 2018, 11:18:31 AM »

I used this technique and it gave me a sudo pwm that works really well!

https://ixox.fr/forum/index.php?topic=69399.0

19

preenfm2 and preenfm3 / Re: Non-linear waveshaping on the PreenFM2

« on: February 25, 2018, 11:17:25 AM »

I made up my own preset with Alg4 using this technique on two operators with LFO’s at differentfrequencies and bias’ and it creates a great pwm effect! Thank you so much!

20

preenfm2 and preenfm3 / Re: TX81Z Waveforms

« on: February 25, 2018, 09:45:41 AM »

I uploaded waveforms I recorded from a real TX81Z with different levels of feedback. If you’re still interested you can find them here:

https://ixox.fr/forum/index.php?topic=69360.0

 

21

preenfm2 and preenfm3 / Re: Reverb Algorithms

« on: February 25, 2018, 09:38:07 AM »

You could try using the envelopes to create a sudo reverb like on the Ensoniq SQ80. I’ve created a sudo delay by setting delays on the envelopes for each operator and then setting them to a macro knob to adjust the delay time. Works great!

22

preenfm2 and preenfm3 / Re: TX81z W1-W8 + Feedback Waveforms .txt Download

« on: November 19, 2017, 10:24:12 PM »

I was looking for exactly this today.  However I'm a bit confused with the screenshots of the waveforms WITHOUT feedback.  The eight waves are just made up of pieces of cosine quadrants.  Waves 1 and 5 look basically right, and waves 3 and 7 look *roughly* like Yamaha claimed.  But waves 2, 4, 6, nd 8 look quite wrong.  Do you have any idea why this might be?  Was Yamaha's DAC that bad?

There is nothing wrong with the waveforms.

As is often the case the purpose of a waveforms graphical representation is not an exact image of the true waveform. For instance on the Waldorf Blofeld the "sawtooth" wave is actually a ramp and the trough is curved. Similarly the "sawtooth" wave of the Dave Smith Mopho looks more like the tooth on a chainsaw.

Please look at the image I attached to see the examples I gave.

23

preenfm2 and preenfm3 / TX81z W1-W8 + Feedback Waveforms .txt Download

« on: November 18, 2017, 01:58:12 AM »

Many people have asked for feedback as an option and compared the PFM2 to Yamaha synths like the TX81z. While this is a completely different instrument I thought it might be interesting to add waveforms from the TX81z and varying feedback levels for each waveform. This took a very long time to get right. Considering the TX waveforms are 4096 samples and the PFM2 has a max 1024 samples they aren't 1:1 but sound basically the same.

The feedback levels only start getting interesting at higher levels. Looking at the waveforms in an oscilloscope I noticed feedback acts a little like a wavefolder + distortion. The highest feedback level without distortion  is level 5. I've included 3 versions of the waveforms. One set without feedback, another set at level 5 feedback, and a final set at level 7 feedback.

Each waveform was recorded in Reaper at 48k 24bit around 46.87hz or F#1 tuned sharp. One cycle at that frequency gives you exactly 1024 samples. I had to fix one of the waveforms at feedback level 7 because it was incredibly unstable and would not stay in tune. Very analog like!

All waveforms are included in the zip file with images that show each waveform.

Enjoy!