Model reference · open weights
supertonic-2 is an open-weight audio or speech model from Supertone. 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
| Released by | Supertone |
|---|---|
| Type | Audio & music |
| Task | Text→speech |
| Runs with | supertonic |
| Released | 2026-01-06 |
| Popularity | 1k downloads / month |
| Licence | Open weights |
About
Supertonic is a lightning-fast, on-device text-to-speech system designed for extreme performance with minimal computational overhead. Powered by ONNX Runtime, it runs entirely on your device—no cloud, no API calls, no privacy concerns.
Supertonic 2 extends multilingual capabilities while maintaining the same inference speed and efficiency as the original.
| Language | Code |
|---|---|
| English | en |
| Korean | ko |
| Spanish | es |
| Portuguese | pt |
| French | fr |
We evaluated Supertonic's performance (with 2 inference steps) using two key metrics across input texts of varying lengths: Short (59 chars), Mid (152 chars), and Long (266 chars).
Metrics:
| System | Short (59 chars) | Mid (152 chars) | Long (266 chars) |
|---|---|---|---|
| Supertonic (M4 pro - CPU) | 912 | 1048 | 1263 |
| Supertonic (M4 pro - WebGPU) | 996 | 1801 | 2509 |
| Supertonic (RTX4090) | 2615 | 6548 | 12164 |
API ElevenLabs Flash v2.5 | 144 | 209 | 287 |
API OpenAI TTS-1 | 37 | 55 | 82 |
API Gemini 2.5 Flash TTS | 12 | 18 | 24 |
API Supertone Sona speech 1 | 38 | 64 | 92 |
Open Kokoro | 104 | 107 | 117 |
Open NeuTTS Air | 37 | 42 | 47 |
Notes:
API= Cloud-based API services (measured from Seoul)Open= Open-source models Supertonic (M4 pro - CPU) and (M4 pro - WebGPU): Tested with ONNX Supertonic (RTX4090): Tested with PyTorch model Kokoro: Tested on M4 Pro CPU with ONNX NeuTTS Air: Tested on M4 Pro CPU with Q8-GGUF
| System | Short (59 chars) | Mid (152 chars) | Long (266 chars) |
|---|---|---|---|
| Supertonic (M4 pro - CPU) | 0.015 | 0.013 | 0.012 |
| Supertonic (M4 pro - WebGPU) | 0.014 | 0.007 | 0.006 |
| Supertonic (RTX4090) | 0.005 | 0.002 | 0.001 |
API ElevenLabs Flash v2.5 | 0.133 | 0.077 | 0.057 |
API OpenAI TTS-1 | 0.471 | 0.302 | 0.201 |
API Gemini 2.5 Flash TTS | 1.060 | 0.673 | 0.541 |
API Supertone Sona speech 1 | 0.372 | 0.206 | 0.163 |
Open Kokoro | 0.144 | 0.124 | 0.126 |
Open NeuTTS Air | 0.390 | 0.338 | 0.343 |
Characters per Second (5-step)
| System | Short (59 chars) | Mid (152 chars) | Long (266 chars) |
|---|---|---|---|
| Supertonic (M4 pro - CPU) | 596 | 691 | 850 |
| Supertonic (M4 pro - WebGPU) | 570 | 1118 | 1546 |
| Supertonic (RTX4090) | 1286 | 3757 | 6242 |
Real-time Factor (5-step)
| System | Short (59 chars) | Mid (152 chars) | Long (266 chars) |
|---|---|---|---|
| Supertonic (M4 pro - CPU) | 0.023 | 0.019 | 0.018 |
| Supertonic (M4 pro - WebGPU) | 0.024 | 0.012 | 0.010 |
| Supertonic (RTX4090) | 0.011 | 0.004 | 0.002 |
This project’s sample code is released under the MIT License. - see the LICENSE for details.
The accompanying model is released under the OpenRAIL-M License. - see the LICENSE file for details.
This model was trained using PyTorch, which is licensed under the BSD 3-Clause License but is not redistributed with this project. - see the LICENSE for details.
Copyright (c) 2026 Supertone Inc.
From the published model card. Full card on the HuggingFace links in the sidebar.
How it works
Using it via the API
Once AxForge deploys supertonic-2 for you, it answers on the OpenAI-compatible API — the same base URL and keys as every other model. (supertonic-2 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="supertonic-2" -F file=@audio.mp3
Create an account — your API key is available in the console. 3M free tokens every 30 days with every new account.