Stable Audio 3 sizes: which one for your job

Stable Audio 3.0 comes in four sizes: Small SFX and Small at 459M parameters for up to 2 minutes, Medium at 1.4B for up to 6:20, and Large at 2.7B, which is available only through the API, a partner, or enterprise licensing. Pick the smallest size that reaches your length, and use Large only if you accept the API route.

The sizes

Music Business Worldwide lists the following. It also reports an AudioSparx training set of 806,284 files, plus LoRA fine-tuning and audio inpainting.

Matching size to job

• Sound effects and short stingers: Small SFX.
• Loops, intros and bumpers under two minutes: Small.
• Full songs and long beds: Medium.
• Large: only when you need it and can use the API or an enterprise arrangement.

How Sume's Music Router handles length

Sume's Music Router takes a prompt of 1 to 5000 characters and picks the engine when model is omitted or set to sume/music-auto, which is Lyria 3.5 today. Routable ids are sume/music-auto, lyria-3.5 and lyria-3-pro. The duration and duration_seconds fields are rejected, so you steer length in the prompt, for example by asking for a 2-minute track or writing timed sections like [0:00-0:30] Intro.

Every Music Router model charges the fixed Music price per audio generation. Read the audio artifact from result.artifacts[] where type is audio. Sume's docs do not list Stable Audio ids, so this is a comparison of approaches, not a drop-in swap.

What to test

Generate the same brief on both routes and compare three things: whether the length lands within your tolerance, whether a loop point is clean, and whether the result is licensed for your use. Check each provider's terms for commercial use before you ship.