[Csnd] Hans Mikelson distortion, slope based delay
| Date | 2012-05-24 14:31 |
| From | Oeyvind Brandtsegg |
| Subject | [Csnd] Hans Mikelson distortion, slope based delay |
| Hi list, I'm working on a lesson on distortion effects, where I'd like to include the delay based distortion effect introduced (afaik) by Hans Mikelson here: http://www.csounds.com/mikelson/index.html#multifx I think this was written in 1999 or so ? (Hans if you're here, please comment) What I want to ask is to get confirmation that my changes to the code has not significantly altered the processing result. I've tried to make the code cleaner, adapt it to a 0dbfs=1 standard, and also secure that the delay time never goes below zero (regardless of the values used for duty and slope). Mikelson's distortion includes both soft clipping and the slope based delay stage, I've also tried to isolate the slope based delay stage. The essential line of code is: (Mikelson version) aout deltapi (2-iduty*asign)/1500 + islope*(asign-aold)/300 (My version) a2 deltap3 ((1-a1)*iduty) + ((a1-an) * islope) + (0.5*iduty) + islope + 0.001 Now, this is taken out of context, and not directly comparable, as the Mikelson version also uses a clipping stage. I have phase differences in the output between the two different version of the code, but the spectrum looks and sounds (in all significant detail) equal (clipping stage omitted). Hans, if you're here, perhaps you can comment? And anyone else too of course, all suggestions and objections welcome. Code for the complete instruments pasted below Oeyvind *** ;--------------------------------------------------------------------------- ; Distortion 2 (Mikelson) ;--------------------------------------------------------------------------- instr 8 igaini = p4 ; Pre gain igainf = p5 ; Post gain iduty = p6 ; Duty cycle offset islope = p7 ; Slope offset izin = p8 ; Input channel izout = p9 ; Output channel asign init 0 ; Delayed signal kamp linseg 0, .002, 1, p3-.004, 1, .002, 0 ; Declick asig zar izin ; Read input channel aold = asign ; Save the last signal asign = igaini*asig/20000 ; Normalize the signal aclip = (8*asign-4)/(1+exp(30*asign-15))/(1+exp(1-asign))+.8 aclip = igainf*aclip*30000 ; Re-amplify the signal atemp delayr .1 ; Amplitude and slope based delay aout deltapi (2-iduty*asign)/1500 + islope*(asign-aold)/300 delayw aclip zaw aout, izout ; Write to output channel endin ;*************************************************** ; slope based delay distortion (Brandtsegg, after Mikelson) ;*************************************************** instr 8 islope = p5 ; amount of slope influence on delay time iduty = p6 ; amount of duty influence on delay time a1 = (read from chn or generate audio signal) ; distortion an1 delay1 a1 ; delay audio by 1 sample aslope = a1 - an1 ; find difference between samples (= slope of the waveform) ; delay time offset to avoid delay time less than zero ioffset = (0.5*iduty) + islope + 0.001 ; delay line processing atemp delayr 1 a2 deltap3 ((1-a1)*iduty) + (aslope * islope) + ioffset delayw a1 ; audio out out a2 endin ;*************************************************** |