Honeycomb by LDM Design

Creating convincing metallic percussion—realistic hi-hats, cymbals, bells, or experimental metallic textures—requires inharmonic resonances that standard harmonic filters can’t produce. Traditional comb filters create evenly spaced harmonic peaks, but real metal doesn’t ring in perfect harmonics. Honeycomb solves this with a unique nested comb filter architecture featuring 16 parallel inharmonic filters arranged in 4 groups, each capable of producing harmonic, odd-harmonic, and inharmonic spectra through coefficient interpolation.

This MaxforLive audio effect is built on research by Jae Hyun Ahn and Richard Dudas, implementing nested comb filters where one comb is placed within the feedback loop of another. This architecture allows independent tuning of outer and inner comb frequencies, with two interpolating coefficients that control harmonic relationships. The result is precise control over inharmonic resonances—essential for metallic sound design, cymbal synthesis, hi-hat creation, riser effects, and experimental timbres impossible to achieve with conventional filters.

Overview & Nested Comb Filter Architecture

Standard comb filters create evenly spaced resonant peaks in the frequency spectrum by delaying the signal and feeding it back into itself. These peaks are harmonically related—perfect for pitched resonances like strings or flutes, but unsuitable for metallic sounds which ring with complex, inharmonic overtones. Honeycomb’s nested comb architecture breaks this harmonic limitation by placing one comb filter inside the feedback loop of another.

Each of Honeycomb’s 16 filters features two independently tunable frequencies: Freq 1 (outer comb) and Freq 2 (inner comb). By nesting the inner comb within the outer comb’s feedback path, the two delay times interact to create complex resonance patterns. Add two interpolating coefficients (C and K), and you gain control over whether those resonances are harmonic, odd-harmonic, or inharmonic—and everything in between.

This implementation is based on the paper by Jae Hyun Ahn and Richard Dudas, “Nested Allpass Filters for Inharmonic Audio Effects.” The mathematical relationships between the coefficients and frequencies create spectral characteristics impossible with traditional filter designs, making Honeycomb uniquely suited for physical modeling of metallic objects.

Sixteen Filters, Four Groups

Honeycomb provides 16 individual nested comb filters arranged into 4 groups of 4 filters each. This architecture allows you to build complex, layered metallic timbres by stacking multiple inharmonic resonances. A single comb filter might create a simple metallic ring, but 16 filters with carefully tuned frequencies and coefficients produce the rich, complex overtones of real cymbals, bells, or gongs.

Each filter can be switched on or off independently to preserve CPU resources—only active filters are processed. This matters when working with 16 computationally intensive nested comb filters. Enable just a few filters for simple metallic accents, or activate all 16 for dense, complex timbres.

The four-group structure provides organizational clarity and additional processing options. Each group offers solo mode (for focused editing), routing control (parallel or serial), group frequency shifting, and frequency linking—features that make managing 16 filters practical rather than overwhelming.

Coefficient Control – Harmonic to Inharmonic

The real power of Honeycomb lies in its two-coefficient system that controls harmonic relationships:

Coefficient 1 (C) determines the basic spectral character. Positive values produce harmonic spectra (evenly spaced peaks). Negative values produce odd-harmonic spectra (every other harmonic) at half the frequency. This coefficient establishes the fundamental resonance structure.

Coefficient 2 (K) acts as an interpolator between different harmonic spacings. When K is zero, peaks are spaced at a frequency corresponding to the sum of the two delay times. When K approaches 1 (assuming positive C), peaks align in a harmonic spectrum at the outer comb frequency. When K approaches -1, peaks form an odd-harmonic spectrum at half that frequency. At values between these extremes (like 0.75), the resonances interpolate between spectra, creating inharmonic relationships.

This coefficient interpolation is what makes Honeycomb special. Real metallic objects don’t ring in perfect harmonics—their overtones are slightly (or dramatically) inharmonic. By adjusting K values, you create these natural inharmonic relationships, producing metallic timbres that sound organic rather than synthetic.

Dual Frequency Control

Each filter features two independently tunable frequencies: Freq 1 (outer comb) and Freq 2 (inner comb). These frequencies determine the delay times of the nested combs, which in turn establish the fundamental pitch regions where resonances occur. The interaction between these two frequencies, mediated by the coefficients, creates the final spectral character.

Tuning is critical for metallic sound design. Small frequency changes produce dramatically different timbres. Frequencies that create simple harmonic relationships (like octaves or perfect fifths) produce more tonal results. Frequencies with complex mathematical relationships create more chaotic, bell-like timbres. Experimentation is essential—the manual explicitly recommends using your ears and experimenting with different frequency combinations to discover useful timbres.

Group Features – Routing, Linking, and Processing

Parallel and Serial Routing: By default, the four filters within each group run in parallel, their outputs summed together. Switch to Serial mode, and the filters cascade—filter 1 feeds filter 2, which feeds filter 3, which feeds filter 4. Serial routing creates more complex resonance interactions as each filter colors the output of the previous one, producing denser, more chaotic timbres.

Frequency Linking: Enable Link mode within a group, and the four filters’ frequencies lock together. Adjust the first filter’s frequency, and the others follow with a fixed Hz offset (set by the Offset parameter). This makes it easy to transpose entire groups or maintain specific frequency relationships while exploring different pitch regions. Instead of adjusting four filters individually, you control all four from a single frequency knob.

Group Frequency Shifting: Each group has its own frequency shifter that shifts the entire group’s output. Unlike pitch shifting (which maintains harmonic relationships), frequency shifting moves all frequencies by a fixed Hz amount, disrupting harmonic relationships and creating inharmonic spectra. This is particularly effective for metallic sounds, adding shimmer, dissonance, or otherworldly character.

Solo Mode: Solo a group to mute all others, making it easy to focus on editing one group’s filters without the complexity of hearing all 16 at once. This is essential for detailed sound design work.

Per-Filter Processing

Each of the 16 filters includes additional processing:

Gain Control attenuates the filter’s output, essential for balancing levels across filters with different resonance characteristics. Some frequency/coefficient combinations produce louder resonances than others, and individual gain controls let you create balanced mixes.

Lowpass Filter (2-pole) cuts high frequencies from each filter’s output. Nested comb filters can produce very bright, harsh high-frequency resonances. The lowpass filter tames these when needed, or leaves them intact when you want aggressive metallic brilliance.

Global Processing

Global Frequency Shift shifts the entire output of all four groups, adding one more layer of inharmonic processing on top of the already complex filter interactions. Use subtle amounts for gentle shimmer, or extreme settings for dramatic pitch-bending effects.

Dry/Wet Mix blends the processed signal with the original input. Pure wet (100%) gives you only the filtered resonances—perfect for using Honeycomb as a metallic resonator or synthesizer. Mix in dry signal to add metallic character to existing sounds without completely replacing them.

Output Gain attenuates the final output. Comb filter resonances can build up significant amplitude, especially when using multiple filters. The built-in limiter prevents speaker damage, but output gain gives you control over overall level. The manual recommends following Honeycomb with EQ to boost high frequencies for effective metallic sounds and attenuate specific resonant spikes that might be too prominent.

Workflow and Sound Design Applications

Metallic Hi-Hats and Cymbals: Feed white noise bursts or short impulses into Honeycomb. Tune the filters to create inharmonic resonances that mimic the spectral characteristics of metal percussion. Adjust coefficients to control harmonic/inharmonic balance, use frequency shifting for shimmer, and layer multiple groups for complex timbres.

Bell and Gong Synthesis: Use Honeycomb as a resonator for synthesis. Feed it impulses or noise with slow attacks, tune filters to create bell-like inharmonic overtones, and use serial routing for complex resonance interactions.

Riser Effects: Send noise with gradual attacks into Honeycomb, automate frequency parameters or global frequency shift to create evolving metallic risers perfect for transitions and builds.

Sound Design and Texture: Process any sound—drums, vocals, synths, field recordings—through Honeycomb to add metallic character. Use subtle settings for gentle shimmer and resonance, or extreme settings for complete transformation into experimental metallic textures.

Physical Modeling: Honeycomb’s nested comb architecture is based on physical modeling research. Use it to model the resonance characteristics of physical objects by carefully tuning frequencies and coefficients to match real-world inharmonic relationships.

Technical Background

Honeycomb implements nested allpass comb filters as described in the paper “Nested Allpass Filters for Inharmonic Audio Effects” by Jae Hyun Ahn and Richard Dudas. This research demonstrates how nesting one comb filter within another’s feedback loop creates control over inharmonic spectra through coefficient interpolation. The device was also inspired by Zion Jaymes’ YouTube videos on cymbal design using physical modeling techniques.

Understanding the underlying theory isn’t required to use Honeycomb effectively, but it helps explain why the coefficient controls behave as they do. The complex mathematical relationships between the two delay times and two coefficients create spectral characteristics that can’t be achieved with simpler filter designs.

How to Use

Insert Honeycomb as an audio effect on any track in Ableton Live. Send audio into it—short impulses with white noise work well for hi-hat sounds, noise with slow attacks creates risers, or process any existing sound for metallic character. Enable one or more filters and set frequencies and coefficient values. The manual emphasizes experimentation—use your ears to find interesting combinations.

Use the Solo function to focus on editing one group at a time. Enable frequency linking when you want to control multiple filters together. Switch between parallel and serial routing to explore different resonance interactions. Add frequency shifting for shimmer and inharmonic character. Use the lowpass filters to tame harsh high frequencies.

The manual strongly recommends placing an EQ after Honeycomb to boost high frequencies for effective metallic sounds and to attenuate specific frequency spikes where resonances might be too prominent. All parameters are fully automatable for evolving metallic textures throughout your track.

Ideal For

Sound designers creating metallic percussion and experimental textures. Electronic producers synthesizing hi-hats, cymbals, and metallic percussion elements. Experimental musicians exploring inharmonic timbres and physical modeling. Anyone working with physical modeling synthesis who needs precise control over inharmonic resonances. Producers seeking unique, complex timbres unavailable from standard harmonic filters. Artists interested in the intersection of academic DSP research and practical music production tools.

What’s Included

• Honeycomb MaxforLive audio effect device with 16 nested comb filters
• Comprehensive reference manual with detailed technical explanations
• 4 groups with solo, routing, frequency linking, and frequency shifting
• Per-filter gain and lowpass filtering
• Global frequency shift, dry/wet mix, and output gain
• Built-in limiter for speaker protection
• Compatible with Ableton Live 11 & 12 (Standard with MaxforLive or Suite)

Requirements

• Ableton Live 11 Standard with MaxforLive installed, or Ableton Live 11/12 Suite
• Mac or Windows operating system

Honeycomb by LDM Design brings academic DSP research into practical music production. Based on nested comb filter architecture by Jae Hyun Ahn and Richard Dudas, this device provides precise control over inharmonic resonances through 16 filters, coefficient interpolation, and comprehensive group processing—essential tools for metallic sound design, cymbal synthesis, and experimental timbres.

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