Model reference · open weights

acestep-5Hz-lm

Available as managed deployment Audio ACE-Step Music / audio 2 variants 9k dl/mo

acestep-5Hz-lm is an open-weight audio or speech model from ACE-Step. AxForge deploys and operates it for you on dedicated EU-owned hardware — with the licence handled where one is required.

Available as managed deployment — configured and operated for you on dedicated EU hardware, quoted per deployment.

What it is

MakerACE-Step
TypeAudio & music
TaskMusic / audio
Parameters (lead)4.2B
Runs withtransformers
Released2026-01-23
Popularity9k downloads / month
LicenceOpen weights

About

What acestep-5Hz-lm is

Model Details

🚀 ACE-Step v1.5 is a highly efficient open-source music foundation model designed to bring commercial-grade music generation to consumer hardware.

Key Features

  • 💰 Commercial-Ready: Unlike many models trained on ambiguous datasets, ACE-Step v1.5 is designed for creators. You can strictly use the generated music for commercial purposes.
  • 📚 Safe & Robust Training Data: The model is trained on a massive, legally compliant dataset consisting of:
    • Licensed Data: Professionally licensed music tracks.
    • Royalty-Free / No-Copyright Data: A vast collection of public domain and royalty-free music.
    • Synthetic Data: High-quality audio generated via advanced MIDI-to-Audio conversion.
  • ⚡ Extreme Speed: Generates a full song in under 2 seconds on an A100 and under 10 seconds on an RTX 3090.
  • 🖥️ Consumer Hardware Friendly: Runs locally with less than 4GB of VRAM.

Technical Capabilities

🌉 At its core lies a novel hybrid architecture where the Language Model (LM) functions as an omni-capable planner: it transforms simple user queries into comprehensive song blueprints—scaling from short loops to 10-minute compositions—while synthesizing metadata, lyrics, and captions via Chain-of-Thought to guide the Diffusion Transformer (DiT). ⚡ Uniquely, this alignment is achieved through intrinsic reinforcement learning relying solely on the model's internal mechanisms, thereby eliminating the biases inherent in external reward models or human preferences. 🎚️

🔮 Beyond standard synthesis, ACE-Step v1.5 unifies precise stylistic control with versatile editing capabilities—such as cover generation, repainting, and vocal-to-BGM conversion—while maintaining strict adherence to prompts across 50+ languages. This paves the way for powerful tools that seamlessly integrate into the creative workflows of music artists, producers, and content creators. 🎸

  • Developed by: [ACE-STEP]
  • Model type: [Text2Music]
  • Language(s): [50+ languages]
  • License: [MIT]

Evaluation

🏗️ Architecture

🦁 Model Zoo

DiT Models

DiT ModelPre-TrainingSFTRLCFGStepRefer audioText2MusicCoverRepaintExtractLegoCompleteQualityDiversityFine-TunabilityHugging Face
acestep-v15-base50MediumHighEasyLink
acestep-v15-sft50HighMediumEasyLink
acestep-v15-turbo8Very HighMediumMediumLink
acestep-v15-turbo-rl8Very HighMediumMediumTo be released

LM Models

LM ModelPretrain fromPre-TrainingSFTRLCoT metasQuery rewriteAudio UnderstandingComposition CapabilityCopy MelodyHugging Face
acestep-5Hz-lm-0.6BQwen3-0.6BMediumMediumWeak
acestep-5Hz-lm-1.7BQwen3-1.7BMediumMediumMedium
acestep-5Hz-lm-4BQwen3-4BStrongStrongStrong

🙏 Acknowledgements

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

📖 Citation

If you find this project useful for your research, please consider citing:

@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}
}

From the published model card. Full card on the HuggingFace links in the sidebar.

Using it via the API

Call it like any OpenAI endpoint

Once AxForge deploys acestep-5hz-lm for you, it answers on the OpenAI-compatible API — the same base URL and keys as every other model. (acestep-5hz-lm below is illustrative; you get the exact model name on deployment.)

$ curl -sS https://api.axforge.ai/v1/audio/transcriptions \
  -H "Authorization: Bearer $AXFORGE_API_KEY" \
  -F model="acestep-5hz-lm" -F file=@audio.mp3

Create an account — your API key is available in the console. 5M tokens/month currently included with every new account at launch.

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