Ternary weights shrink a speech model from 2,472 MB to 181 MB with just +0.4pt WER

lmoroney · x · 2026-10-25

Laurence Moroney shares a hands-on extreme quantization case: constraining 98% of NVIDIA Parakeet-TDT-0.6B-v2's encoder parameters to just -1, 0, or +1 (one scale per row) cuts the weight file from 2,472 MB to 180.8 MB, while mean WER across seven test sets rises only from 6.45% to 6.84%.

Accuracy is largely recovered via quantization-aware training with distillation from the original model: 250,000 steps on 33,000 hours of audio, taking 69.3 hours on a single RTX 5090. The model card is candid about weak spots, with the biggest gap on Common Voice, which wasn't in the training mix.

His learning tip: to really understand quantization, read a model card like this end to end and try to reproduce one row of its results table.

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