diff --git a/synth/config.go b/synth/config.go
index 67fcb2b..7636102 100644
--- a/synth/config.go
+++ b/synth/config.go
@@ -11,6 +11,53 @@ const (
 	WhisperFloor     = 0.03                               // D-08/D-09: 3% of max amplitude
 )
 
+// WaveformType selects the harmonic preset for a synthesis layer.
+// The zero value WaveformCustom preserves existing hand-tuned harmonics in FreqConfig.Harmonics.
+type WaveformType int
+
+const (
+	WaveformCustom   WaveformType = iota // zero value: use FreqConfig.Harmonics as-is
+	WaveformSine                         // pure fundamental, single harmonic
+	WaveformSquare                       // odd harmonics with 1/k amplitude (bandlimited)
+	WaveformSawtooth                     // all harmonics with 1/k amplitude (bandlimited)
+	WaveformTriangle                     // odd harmonics with alternating 1/k^2 amplitude (bandlimited)
+)
+
+// WaveformPresetHarmonics returns the bandlimited harmonic series for the given waveform type
+// at the given base frequency and sample rate. Returns nil for WaveformCustom.
+// All returned harmonics are below Nyquist (sampleRate/2).
+func WaveformPresetHarmonics(wt WaveformType, baseHz float64, sampleRate int) []HarmonicDef {
+	nyquist := float64(sampleRate) / 2.0
+	switch wt {
+	case WaveformCustom:
+		return nil
+	case WaveformSine:
+		return []HarmonicDef{{Ratio: 1, Amplitude: 1.0}}
+	case WaveformSquare:
+		var harmonics []HarmonicDef
+		for k := 1; float64(k)*baseHz < nyquist; k += 2 {
+			harmonics = append(harmonics, HarmonicDef{Ratio: k, Amplitude: 1.0 / float64(k)})
+		}
+		return harmonics
+	case WaveformSawtooth:
+		var harmonics []HarmonicDef
+		for k := 1; float64(k)*baseHz < nyquist; k++ {
+			harmonics = append(harmonics, HarmonicDef{Ratio: k, Amplitude: 1.0 / float64(k)})
+		}
+		return harmonics
+	case WaveformTriangle:
+		var harmonics []HarmonicDef
+		sign := 1.0
+		for k := 1; float64(k)*baseHz < nyquist; k += 2 {
+			harmonics = append(harmonics, HarmonicDef{Ratio: k, Amplitude: sign / float64(k*k)})
+			sign = -sign
+		}
+		return harmonics
+	default:
+		return nil
+	}
+}
+
 // HarmonicDef defines one partial in an additive synthesizer.
 type HarmonicDef struct {
 	Ratio     int     // harmonic number: 1=fundamental, 2=octave, 3=fifth+octave, etc.
@@ -19,29 +66,30 @@ type HarmonicDef struct {
 
 // FreqConfig holds synthesis parameters for one traffic class.
 type FreqConfig struct {
-	BaseHz    float64
-	Harmonics []HarmonicDef
-	Pan       float64 // [-1, 1]: -1=full left, 0=center, +1=full right
+	BaseHz       float64
+	Harmonics    []HarmonicDef
+	Pan          float64      // [-1, 1]: -1=full left, 0=center, +1=full right
+	WaveformType WaveformType // zero value WaveformCustom uses Harmonics as-is
 }
 
 // ClassFreqConfigs maps each traffic class to its synthesis parameters.
 // Frequencies use musical intervals per D-02/D-03. Harmonics per D-05/D-06.
 // Pan positions per D-12.
 var ClassFreqConfigs = map[classify.TrafficClass]FreqConfig{
-	classify.ClassICMP:     {65.0, []HarmonicDef{{1, 1.0}, {2, 0.4}, {3, 0.15}}, 0.0},
-	classify.ClassDNS:      {110.0, []HarmonicDef{{1, 1.0}, {2, 0.5}, {3, 0.25}}, -0.2},
-	classify.ClassHTTPS:    {175.0, []HarmonicDef{{1, 1.0}, {2, 0.6}, {3, 0.3}}, 0.2},
-	classify.ClassHTTP:     {220.0, []HarmonicDef{{1, 1.0}, {2, 0.5}, {4, 0.2}}, -0.35},
-	classify.ClassSSH:      {330.0, []HarmonicDef{{1, 1.0}, {3, 0.6}, {5, 0.3}}, 0.35},
-	classify.ClassSMTP:     {440.0, []HarmonicDef{{1, 1.0}, {2, 0.3}, {3, 0.1}}, -0.55},
-	classify.ClassNTP:      {520.0, []HarmonicDef{{1, 1.0}, {2, 0.25}}, 0.55},
-	classify.ClassDHCP:     {600.0, []HarmonicDef{{1, 1.0}, {2, 0.35}, {3, 0.15}}, -0.75},
-	classify.ClassOtherTCP: {700.0, []HarmonicDef{{1, 1.0}, {2, 0.2}}, 0.75},
-	classify.ClassOtherUDP: {780.0, []HarmonicDef{{1, 1.0}, {2, 0.2}}, -0.75},
+	classify.ClassICMP:     {BaseHz: 65.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.4}, {3, 0.15}}, Pan: 0.0},
+	classify.ClassDNS:      {BaseHz: 110.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.5}, {3, 0.25}}, Pan: -0.2},
+	classify.ClassHTTPS:    {BaseHz: 175.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.6}, {3, 0.3}}, Pan: 0.2},
+	classify.ClassHTTP:     {BaseHz: 220.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.5}, {4, 0.2}}, Pan: -0.35},
+	classify.ClassSSH:      {BaseHz: 330.0, Harmonics: []HarmonicDef{{1, 1.0}, {3, 0.6}, {5, 0.3}}, Pan: 0.35},
+	classify.ClassSMTP:     {BaseHz: 440.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.3}, {3, 0.1}}, Pan: -0.55},
+	classify.ClassNTP:      {BaseHz: 520.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.25}}, Pan: 0.55},
+	classify.ClassDHCP:     {BaseHz: 600.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.35}, {3, 0.15}}, Pan: -0.75},
+	classify.ClassOtherTCP: {BaseHz: 700.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.2}}, Pan: 0.75},
+	classify.ClassOtherUDP: {BaseHz: 780.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.2}}, Pan: -0.75},
 	// D-05: Unknown buckets in 850-1100 Hz dissonant range, detuned intervals
 	// D-06: Same dissonant harmonic character {1,1.0},{2,0.8},{3,0.4} for all 4
-	classify.ClassUnknown1: {862.0, []HarmonicDef{{1, 1.0}, {2, 0.8}, {3, 0.4}}, 0.6},
-	classify.ClassUnknown2: {920.0, []HarmonicDef{{1, 1.0}, {2, 0.8}, {3, 0.4}}, -0.6},
-	classify.ClassUnknown3: {981.0, []HarmonicDef{{1, 1.0}, {2, 0.8}, {3, 0.4}}, 0.9},
-	classify.ClassUnknown4: {1047.0, []HarmonicDef{{1, 1.0}, {2, 0.8}, {3, 0.4}}, -0.9},
+	classify.ClassUnknown1: {BaseHz: 862.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.8}, {3, 0.4}}, Pan: 0.6},
+	classify.ClassUnknown2: {BaseHz: 920.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.8}, {3, 0.4}}, Pan: -0.6},
+	classify.ClassUnknown3: {BaseHz: 981.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.8}, {3, 0.4}}, Pan: 0.9},
+	classify.ClassUnknown4: {BaseHz: 1047.0, Harmonics: []HarmonicDef{{1, 1.0}, {2, 0.8}, {3, 0.4}}, Pan: -0.9},
 }