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exExperimentos
Speech & codecsResults9 Oct 2026

MOSS: the best similarity score did not mean the fewest word errors

Nine generator profiles were tested against BF16 plus the same Argentina LoRA. The English study retained ninety complete generations, controlled decoder runs and a timing recheck. A separate Spanish extension used one generation per phrase.

Key finding

Q6/Q8 built directly from BF16 had the fewest Spanish ASR edits, while the older Q4 had higher speaker cosine.

Edited finding from the pinned experiment record. The report and figure metadata preserve the original workload and limits.

The boundary

Three phrases per language, one seed and one reference voice. The unchanged shared codec makes decoder controls consistency tests, not a generator ranking.

Data

Reviewed aggregate results with explicit units, sources and qualification limits. Different cohorts remain separate.

Recorded result

Generator variants changed Spanish word errors

Separate Spanish extension · three phrases · one seed · same conditioning

Generator variants changed Spanish word errorsBF16 + same LoRA: 4 ASR edits / 65 words; Older Q4: 9 ASR edits / 65 words; Older Q5: 25 ASR edits / 65 words; Q6/Q8 from 8-bit: 33 ASR edits / 65 words; Q6/Q8 from BF16: 2 ASR edits / 65 words; oMLX Q3/Q4/Q6: 10 ASR edits / 65 words; oMLX Q4/Q5/Q6: 47 ASR edits / 65 words; oMLX Q5/Q6: 9 ASR edits / 65 words; Uniform Q6: 4 ASR edits / 65 words. One generation per phrase. Baseline uses split generation/decoding; no comparable end-to-end latency claim.BF16 + same LoRA4BF16 + same LoRA: 4 ASR edits / 65 wordsOlder Q49Older Q4: 9 ASR edits / 65 wordsOlder Q525Older Q5: 25 ASR edits / 65 wordsQ6/Q8 from 8-bit33Q6/Q8 from 8-bit: 33 ASR edits / 65 wordsQ6/Q8 from BF162Q6/Q8 from BF16: 2 ASR edits / 65 wordsoMLX Q3/Q4/Q610oMLX Q3/Q4/Q6: 10 ASR edits / 65 wordsoMLX Q4/Q5/Q647oMLX Q4/Q5/Q6: 47 ASR edits / 65 wordsoMLX Q5/Q69oMLX Q5/Q6: 9 ASR edits / 65 wordsUniform Q64Uniform Q6: 4 ASR edits / 65 words0ASR edits / 65 words
  1. BF16 + same LoRA4
  2. Older Q49
  3. Older Q525
  4. Q6/Q8 from 8-bit33
  5. Q6/Q8 from BF162
  6. oMLX Q3/Q4/Q610
  7. oMLX Q4/Q5/Q647
  8. oMLX Q5/Q69
  9. Uniform Q64

ASR edits / 65 words

One generation per phrase. Baseline uses split generation/decoding; no comparable end-to-end latency claim.

View data & source
Generator variants changed Spanish word errors · ASR edits / 65 words
ConfigurationValue
BF16 + same LoRA4
Older Q49
Older Q525
Q6/Q8 from 8-bit33
Q6/Q8 from BF162
oMLX Q3/Q4/Q610
oMLX Q4/Q5/Q647
oMLX Q5/Q69
Uniform Q64

Origin: reviewed report table. Revision 7e6fdbe3b1d1.

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Write-ups

Report moss-tts-mlx/chatterbox-fidelity-2026-10-09/README.md

Porting the evaluation method

Nine generator profiles were tested against BF16 plus the same Argentina LoRA. The English study retained ninety complete generations, controlled decoder runs and a timing recheck. A separate Spanish extension used one generation per phrase.

Two metrics, different answers

The directly-from-BF16 Q6/Q8 profile had 2/65 Spanish ASR edits and numerical weight RMS error 2.127%. Older Q4 had 9/65 edits but higher Spanish speaker cosine, 0.95181 versus 0.91631. A Q4/Q5/Q6 mix had a fast 8.167-second English warm median yet 47/65 Spanish edits.

All controlled decoder outputs matched because every generator profile reused the same codec and codes. That verifies the pipeline control, while saying nothing about which quantized generator preserves the best voice.

Preserve the uncomfortable evidence

Forty-two of ninety complete English clips approached the 400-token ceiling. The original reference encountered severe memory pressure and repeated words. Spanish BF16 generation and decoding had to run in separate processes after failed attempts, so that extension has no comparable full-pipeline latency claim.

The useful finding is a trade-off between storage, content and identity proxies. Larger frozen corpora and human listening should precede a general recommendation.

Evidence and publication boundary

This is an edited account of the recorded experiment. The linked archive is private; the methods, aggregate findings and limits are included above. Reference recordings, raw conversations, authentication material and workstation configuration are excluded.

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