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ACE-Step/acestep-v15-xl-sft

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ACE-Step 1.5 XL — SFT (4B DiT)

Project |

Hugging Face |

ModelScope |

Space Demo |

Discord |

Tech Report

Model Details

This is the XL (4B) SFT variant of ACE-Step 1.5 — a supervised fine-tuned model with ~4B parameters. SFT provides higher audio quality with CFG (Classifier-Free Guidance) support for fine-grained prompt adherence control.

XL Architecture

| Parameter | Value |

|-----------|-------|

| DiT Decoder hidden_size | 2560 |

| DiT Decoder layers | 32 |

| DiT Decoder attention heads | 32 |

| Encoder hidden_size | 2048 |

| Encoder layers | 8 |

| Total params | ~4B |

| Weights size (bf16) | ~18.8 GB |

| Inference steps | 50 (with CFG) |

GPU Requirements

| VRAM | Support |

|------|---------|

| ≥12 GB | With CPU offload + INT8 quantization |

| ≥16 GB | With CPU offload |

| ≥20 GB | Without offload |

| ≥24 GB | Full quality (XL + 4B LM) |

All LM models (0.6B / 1.7B / 4B) are fully compatible with XL.

Key Features

  • 💰 Commercial-Ready: Trained on legally compliant datasets. Generated music can be used for commercial purposes.
  • 📚 Safe Training Data: Licensed music, royalty-free/public domain, and synthetic (MIDI-to-Audio) data.
  • 🎯 CFG Support: Fine-tune prompt adherence with guidance scale control.
  • 🔮 Highest Quality: SFT + 4B parameters = the highest quality variant.

Quick Start

# Install ACE-Step
git clone https://github.com/ace-step/ACE-Step-1.5.git
cd ACE-Step-1.5
pip install -e .

# Download this model
huggingface-cli download ACE-Step/acestep-v15-xl-sft --local-dir ./checkpoints/acestep-v15-xl-sft

# Run with Gradio UI
python acestep --config-path acestep-v15-xl-sft

Model Zoo

XL (4B) DiT Models

| DiT Model | CFG | Steps | Quality | Diversity | Tasks | Hugging Face | ModelScope |

|-----------|:---:|:-----:|:-------:|:---------:|-------|--------------| ----------- |

| acestep-v15-xl-base | ✅ | 50 | High | High | All (extract, lego, complete) | Link | Link |

| acestep-v15-xl-sft | ✅ | 50 | Very High | Medium | Standard | This repo | Link |

| acestep-v15-xl-turbo | ❌ | 8 | Very High | Medium | Standard | Link | Link |

LM Models (all compatible with XL)

| LM Model | Params | Audio Understanding | Composition | Hugging Face | ModelScope |

|----------|:------:|:-------------------:|:-----------:|--------------| ----------- |

| acestep-5Hz-lm-0.6B | 0.6B | Medium | Medium | Link | Link |

| acestep-5Hz-lm-1.7B | 1.7B | Medium | Medium | Included in main | Included in main |

| acestep-5Hz-lm-4B | 4B | Strong | Strong | Link | Link |

Acknowledgements

This project is co-led by ACE Studio and StepFun.

Citation

@misc{gong2026acestep,
    title={ACE-Step 1.5: Pushing the Boundaries of Open-Source Music Generation},
    author={Junmin Gong, Yulin Song, Wenxiao Zhao, Sen Wang, Shengyuan Xu, Jing Guo},
    howpublished={\url{https://github.com/ace-step/ACE-Step-1.5}},
    year={2026},
    note={GitHub repository}
}