RFD 1169: The audio tower for Qwen3-VL, and which half compiles
Problem
RFD 1155 abandoned Gemma 4 and left one thing open: what Qwen3-VL does not carry is sound. An AuT encoder with an MLP projector, taking 128-bin log-mel into the decoder’s 4096 space, closes that — the pattern RFD 1157 established for vision.
Decision
The tower is a plausible device half. A Whisper-shaped encoder is Conv, MatMul, Softmax, LayerNormalization and gelu’s Erf, all inside DEVICE_OPS, and PROJECTOR_TYPE_QWEN3A’s conv2d front end shows the log-mel is a single-channel image — escaping the input-rank refusal that stopped Pixal3D.
The blocker is our own fork. clip_init_hailo hardcodes CLIP_MODALITY_VISION; the mtmd around it already carries CLIP_MODALITY_AUDIO and PROJECTOR_TYPE_QWEN3A.
No projector transfers, and the AuT source is old. Qwen3-Omni is 1280 wide over a 2048 decoder, has no standalone checkpoint, and predates Qwen3-VL-8B. Qwen3.5-Omni has no official release. Take Qwen3-ASR-1.7B instead — Apache-2.0, ungated, 128-bin, newer than our base, 2.04 GB at eight bits.
A voice is available; it is the acceleration that is not. Qwen3-TTS-12Hz-1.7B-CustomVoice is Apache-2.0 and clones. Its autoregressive stage is RFD 1126’s obstacle and runs on the host — at 12 Hz, 120 steps for ten seconds of speech. DETAILS.md has the widths, the dates and the fixed window.