Qwen Concept 27B for Apple Silicon (MLX, 8-bit)

An MLX conversion of ConceptCountry/qwen-concept-27b (revision 4c96373, bf16 weights). Qwen Concept 27B is Qwen3.8-27B with nine MLP down-projections edited by Concept Country so that the model reaches its answer with less thinking (paper). This build quantises the language model to 8-bit (affine, group 64) and keeps the vision tower in bf16, so it runs in mlx-lm (text) and mlx-vlm (text and images). Size: 29.5 GB.

Published by NetProjects (Internet Projects Ltd). Not affiliated with Concept Country or Alibaba Cloud.

Build Size Same next token as bf16
netprojects/Qwen-Concept-27B-MLX-6bit (recommended) 22.8 GB 98.6%
netprojects/Qwen-Concept-27B-MLX-8bit 29.5 GB 99.0%
netprojects/Qwen-Concept-27B-MLX-4bit 16.1 GB 95.3%
netprojects/Qwen-Concept-27B-MLX-bf16 54.7 GB reference

The shorter thinking holds after quantisation

Hard math problems (MATH-500, level 5) with thinking on and greedy decoding, the same problems and settings for every model, on a MacBook Pro M5 Max (128 GB), 10 November 2026.

40 problems, 3,072-token cap, both models at 4-bit:

Plain Qwen3.8-27B 4-bit Qwen Concept 27B 4-bit
Thinking tokens, mean 1,746 1,202 (31% fewer)
Thinking tokens, median 1,477 673
Finished thinking within the cap 58% 83%
Correct final answer 55% 73%
Time for the run 19 min 12 min

The first 16 of those problems with a 2,048-token cap, mean thinking tokens: plain Qwen3.8-27B 4-bit 1,178; Qwen Concept 4-bit 876, 6-bit 801, 8-bit 909. Concept Country reports 27 to 54% fewer thinking tokens on its own benchmarks at Q8, so the effect carries over to every build here. The plain model is mlx-community/Qwen3.8-27B-4bit. Answers are scored by exact match of the boxed result; most of the accuracy difference comes from finishing within the cap more often.

"Same next token" in the table above compares each build with the MLX bf16 build over 12 prompts (thinking on and off), 96 teacher-forced tokens each.

Use

pip install -U mlx-lm        # text
mlx_lm.generate --model netprojects/Qwen-Concept-27B-MLX-8bit --prompt "How many primes are there below 100?" --max-tokens 4096

pip install -U mlx-vlm       # text and images
mlx_vlm.generate --model netprojects/Qwen-Concept-27B-MLX-8bit --image photo.jpg --prompt "Describe the scene." --max-tokens 1024

mlx_lm.server and mlx_vlm.server serve it with an OpenAI-compatible API. Tested with mlx 0.32.4, mlx-lm 0.32.2 and mlx-vlm 0.7.11. For thinking mode the Qwen3.8 card recommends temperature 1.0, top-p 0.95, top-k 20.

What was checked

  • The edit is intact. Compared tensor by tensor with plain Qwen3.8-27B, 842 of 851 language-model tensors are identical and exactly nine differ: mlp.down_proj of layers 32, 34, ..., 48, each by 0.4 to 0.6% in norm. This matches the EDIT_SPEC.json that ships with the model and is included here.
  • Source files. All 33 files of the upstream bf16 folder match its SHA256SUMS.
  • Images. The 4-bit, 6-bit and 8-bit builds each describe a test image correctly in mlx-vlm.

License

Apache-2.0, as the original model and Qwen3.8-27B. LICENSE is the Apache-2.0 text from the upstream repository and NOTICE describes the conversion and credits Concept Country and Alibaba Cloud.

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