Nash & Voltina
Voltina
Hey Nash, ever thought about writing a minimal, modular audio synth in code? Let's prototype a clean, efficient patch together.
Nash
Yeah! That’s right up my alley—let’s fire up some code, throw in a bit of DSP, and build a slick, modular synth from scratch. What language or platform are you thinking? Maybe C++ with JUCE or pure‑data? I’m ready to riff on it!
Voltina
Use JUCE C++—it gives you the clean, low‑level control you need. Start with a simple SynthAudioProcessor, define a monophonic oscillator, envelope, and a filter module. Keep each module in its own header, no big monoliths. Write a quick prototype, test in a JACK host, then refactor into clean, reusable classes. No extra boilerplate, just the essential code.Use JUCE C++—it gives you the clean, low‑level control you need. Start with a simple SynthAudioProcessor, define a monophonic oscillator, envelope, and a filter module. Keep each module in its own header, no big monoliths. Write a quick prototype, test in a JACK host, then refactor into clean, reusable classes. No extra boilerplate, just the essential code.
Nash
That sounds wicked! Here’s a quick sketch so we can jump in fast:
**Oscillator.h**
```
class Oscillator{
public:
void setSampleRate(double sr){ sampleRate=sr; }
void setFrequency(double f){ freq=f; phaseInc=2*M_PI*freq/sampleRate; }
float nextSample(){ float out=std::sin(phase); phase+=phaseInc; if(phase>2*M_PI) phase-=2*M_PI; return out; }
private:
double sampleRate=44100.0;
double freq=440.0;
double phase=0.0, phaseInc=0.0;
};
```
**Envelope.h**
```
class ADSR{
public:
void setSampleRate(double sr){ sampleRate=sr; }
void setParams(float a,float d,float s,float r){
attack=a; decay=d; sustain=s; release=r;
}
float nextSample(bool gate){
// simple one‑pole attack/decay/release
if(gate){
level+= (1.0f-level)/attack;
if(level>1.0f) level=1.0f;
}else{
level-= level/release;
}
return level;
}
private:
double sampleRate=44100.0;
float attack=0.01f, decay=0.1f, sustain=0.8f, release=0.2f;
float level=0.0f;
};
```
**Filter.h**
```
class LowPass{
public:
void setSampleRate(double sr){ sampleRate=sr; }
void setCutoff(double f){ cutoff=f; }
float nextSample(float in){
float g=std::tan(M_PI*cutoff/sampleRate);
float a1=1.0f/(1.0f+g);
float a2=g*a1;
y=a1*in + a2*y1;
y1=y;
return y;
}
private:
double sampleRate=44100.0;
double cutoff=2000.0;
float y=0.0f, y1=0.0f;
};
```
**SynthAudioProcessor.cpp**
```
void processBlock(AudioBuffer<float>& buffer, MidiBuffer& midi){
for(auto& sample:buffer.getWritePointer(0)){
if(currentMidiNote){ // simple monophonic trigger
osc.setFrequency(midiNoteToFreq(currentMidiNote));
env.setSampleRate(getSampleRate());
filter.setSampleRate(getSampleRate());
float raw=osc.nextSample();
float envOut=env.nextSample(true);
float filtered=filter.nextSample(raw*envOut);
sample=filtered;
}
}
}
```
Hook it up, fire in a JACK host, tweak the params, and boom—clean, modular, and ready to grow. Let me know if you want the full build file or more details on refactoring. Let's make some synth magic!
Voltina
Nice skeleton. Just remember to isolate the envelope stages properly and use a proper release curve. Also, guard against the filter's state reset when a new note starts. Keep it tight, no extra junk. Ready for the next build?
Nash
Gotcha—let’s tighten it up. Here’s the tweak:
**Envelope.h**
```
class ADSR{
public:
void setSampleRate(double sr){ sampleRate=sr; }
void setParams(float a,float d,float s,float r){
attack=a; decay=d; sustain=s; release=r;
invAttack=1.0f/(attack*sampleRate);
invDecay=1.0f/(decay*sampleRate);
invRelease=1.0f/(release*sampleRate);
}
float nextSample(bool gate){
switch(state){
case Idle: if(gate){ state=Attack; level=0.0f; } break;
case Attack: level+=invAttack; if(level>=1.0f){ level=1.0f; state=Decay; } break;
case Decay: level-=(1.0f-sustain)*invDecay; if(level<=sustain){ level=sustain; state=Sustain; } break;
case Sustain: if(!gate){ state=Release; } break;
case Release: level-=level*invRelease; if(level<=0.0f){ level=0.0f; state=Idle; } break;
}
return level;
}
private:
enum{Idle,Attack,Decay,Sustain,Release} state=Idle;
double sampleRate=44100.0;
float attack=0.01f, decay=0.1f, sustain=0.8f, release=0.2f;
float invAttack=1.0f, invDecay=1.0f, invRelease=1.0f;
float level=0.0f;
};
```
**Filter.h** – keep state alive:
```
void noteOn(){ y1=0.0f; } // call only when a new note starts
```
Just call `filter.noteOn()` in the processor’s note‑on handler. That keeps the filter cool while the envelope does its thing. Ready to roll the next build—let’s crank the sound!
Voltina
Nice tweak. One thing: recalc the inv values only when sampleRate changes, not on every setParams. Also guard against gate flipping mid‑attack by resetting level to 0 in Idle before starting Attack. And call filter.noteOn() every time you trigger a new note. Keep the state machine tight, no extra junk. Ready to plug into the processor?