# Bug report draft: compiled network passes audio UNFILTERED inside a HardcodedMasterFX (raw node works)

[Phelan Kane]

Hiya @Christoph-Hart

Me and my fav Bot (RIP Fable) has identified an issue with audio processing and modulations in HardcodedMasterFX that sit inside a master container (i.e. a top level filter for my device that is obs monophonic due to voicing reasons).

I hope the below explains everything. Happy to drop a minimal script if needed.

Thanks

Phelan

Adjacent to the resolved "HISE 4.1 Hardcoded Master & Poly FX P1 P2 Modulation" thread (forum topic 13276).

---

Environment

• HISE develop, version 4.9.2 (running commit 8606dea6), macOS, Apple Silicon.
• A custom C++ SNEX filter node (ZDF filter, 6 params; param 0 = Cutoff/Frequency, 1 = Res/Resonance).

Context

After the 4.1 P1/P2 modulation breaking change (params no longer auto-modulated; must opt in per parameter), I'm trying to restore modulation on a global filter that sits in a HardcodedMasterFX.

What works

• The RAW C++ node placed directly in the HardcodedMasterFX FILTERS audio correctly. (But its params can no longer be modulated by the P1/P2 slots, as expected after the breaking change - createExternalModulationInfo is not implemented on it.)
• The SAME node wrapped in a compiled network and used POLYPHONICALLY in a HardcodedPolyphonicFX (per-voice) filters AND modulates correctly. This is my sampler filter and it is fine.

What doesn't (the bug)

To get P1/P2 modulation back on the MASTER (mono) filter, I wrapped the node in a compiled network:

• container.chain -> single C++ filter node
• AllowCompilation="1", NO AllowPolyphonic (so it's monophonic for the master FX)
• container params Cutoff/Res have ExternalModulation="Combined" connected to the node's Frequency/Resonance.

Result in the HardcodedMasterFX:

• P1/P2 modulation now works (the matrix/extra_mod drives Cutoff/Res).
• Parameter changes reach the node (verified via scripting: getAttribute(0) returns the set cutoff, e.g. 2401 Hz).
• The effect is NOT bypassed (isBypassed() == false).
• BUT the audio passes through UNFILTERED at any cutoff/topology/response. The wrapped node never cooks its coefficients - it behaves as if prepare()/sampleRate never reached the inner node.

Earlier I also tried the POLYPHONIC network (AllowPolyphonic=1) in the master FX: that produced SILENCE (channel/voice mismatch), which is why I made the monophonic variant.

Questions

1. Should a monophonic compiled network prepare/process its inner node inside a HardcodedMasterFX? It currently passes audio through unprocessed (inner node not prepared) while the raw node prepares fine.
2. What is the recommended way to get a node to BOTH filter audio AND expose P1/P2 modulation inside a HardcodedMasterFX?
3. For C++ nodes specifically: what is the exact signature/usage of createExternalModulationInfo to declare params 0 and 1 as Combined-modulatable on the raw node (so I can skip the network wrapper entirely)? You mentioned "with C++ nodes you can directly call a method that defines the parameter's modulation connections" - a minimal example would let me do this directly.