More Dominator Deconstruction.

Another attempt at the rave hoover sound, this time from Wouter Snoei on the SC-Users list, probably the best so far and based on further research into the Alpha Juno 2. Here's the code,

(
SynthDef( "hoover", { |freq = 220, amp = 0.1, lgu = 0.1, lgd = 1, gate = 1|
var pwm, mix, env;

freq = freq.cpsmidi.lag(lgu,lgd).midicps;
freq = SinOsc.kr( { 2.9 rrand: 3.1 }!3, {2pi.rand}!3 ).exprange( 0.995, 1.005 ) * freq;
pwm = SinOsc.kr( {2.0 rrand: 4.0}!3 ).range(0.125,0.875);

// the saw/pulses
mix = (LFSaw.ar( freq * [0.25,0.5,1], 1 ).range(0,1)
               * (1 - LFPulse.ar(freq * [0.5,1,2], 0, pwm))).sum * 0.1;

// the bass
mix = mix + LFPar.ar( freq * 0.25, 0, 0.1 );

// eq for extra sharpness
mix = BPeakEQ.ar( mix, 6000, 1, 3 );
mix = BPeakEQ.ar( mix, 3500, 1, 6 );

// kind of chorus
mix = mix + CombC.ar( mix.dup, 1/200,
                       SinOsc.kr( 3, [0.5pi, 1.5pi] ).range(1/300,1/200),
               0.0 ) * 0.5;

env = EnvGen.kr( Env.asr, gate );

Out.ar( 0, mix * env * amp );
}).store;
)

(
p = Pmono(\hoover,
               \dur, Pseq([0.25,0.5,7, 0.25]* 0.24, inf),
               \lgu, 0.15,
               \lgd, Pseq([ 0.1, 0.1, 1.5, 0.25], inf ),
               \midinote, Pseq([20, 67, 62, 20] , inf)).play;
)
p.stop;

(
p = Pmono(\hoover, \dur, 0.24,
       \lgu, 0.2,
       \lgd, Pseq([1,1,2,0.5,2,2,2,2], inf ),
        \midinote, Pseq([55, 40, 67, 55, 40, 55, 53, 52], inf)).play;
)
p.stop;

Wouter's come up with a more accurate version of the pulse width modulation, certainly more accurate than my complete guess work and it sounds great.

Here's a little line of code taken from Wouter's post that may offer a bit of an explaination of what's going on with the modulation.

{ LFSaw.ar( 200, 1 ).range(0,1) * (1-LFPulse.ar( 400, 0, 2/3 )) }.plot;

If you run it you should get this plot,



You can see the waveform is a sort of flattened saw wave, this might explain why Dan had trouble identifying what it was.

Deconstructing the Dominator

Dan's got a post over on his blog about reverse engineering the "hoover sound' found in the old school rave classic Dominator by Human Resource. He took a pretty technical approach and did various forms of analysis to come up with something that sound pretty good.
I thought I'd have a go myself, but I decided to take a more direct approach and look it up. I found this wikipedia article about it, it turns out that Human Resource were using a Roland Alpha Juno 2 to create that sound, a mid 80's digital/analogue hybrid synth. There's a good explanation of it's features here, importantly though, it does have a chorus unit built in, which Dan did identify as being the key feature of the sound.

Here's my re-construction attempt, I did start out to try and recreate the functions of an Alpha Juno 2, but in the end I mostly just improvised.

(
SynthDef(\aj2, {
arg freq = 440, gate = 1, lagLev = 0.01, predelay=0.01, speed=0.05, depth=0.01, ph_diff=0.5;
 var width1, width2, width3, osc1, osc2, osc3, filterOut, mix, sig, modulators, numDelays = 8, lfo; 
 width1 = SinOsc.ar(4, 0, 0.8, 0.2).abs;
 width2 = SinOsc.ar(6, 0, 0.8, 0.2).abs;
 width3 = SinOsc.ar(2, 0, 0.8, 0.2).abs;
 lfo = SinOsc.kr(5, 0, 5);
 osc1 = Pulse.ar(Lag.kr(freq + lfo), width1);
 osc2 = Pulse.ar(Lag.kr((freq/2) + lfo), 0.5);
 osc3 = Pulse.ar(Lag.kr((freq*2) + lfo), width3);
 mix = Mix.new([osc1, osc2, osc3]);
 modulators = Array.fill(numDelays, {arg i;
          SinOsc.kr(speed * rrand(0.94, 1.06), ph_diff * i, depth, predelay);}); 
    sig = DelayC.ar(mix, 0.5, modulators);  
    sig = sig.sum; 
    Out.ar(0, sig.dup)
}).store
)

p = Pmono(\aj2, \dur, 0.24, \midinote, Pseq([40, 67, 64, 62, 62, 62, 62, 62], inf)).play;

I've got three pulse width modulated square wave oscillators here, modulated with low frequency SinOscs and some vibrato added with another low frequency SinOsc. These are put through a chorus efect taken from the ixi-audio.com tutorial, featured here before.

My patch is mostly based on random guesswork and a little bit of research, but it sounds okay, though probably not as good as Dan's scientific attempt.