Migrating off Simba 1.6 (simba-english, simba-multilingual)

simba-english and simba-multilingual — the Simba 1.6 pair — are being withdrawn. This page is the one-stop migration guide: what changes, which model to move to, and how to buy time if you need it. The decision and the two dates were announced in the changelog entry that kicked this off.

If your synthesis requests set model to simba-english or simba-multilingual, they keep working after 2026-11-21, but the model behind them changes on that day. From then simba-multilingual is served by our current multilingual model, and simba-english by simba-3.2 for English and the multilingual model for any other language. To choose the model yourself and test your voices first, switch to simba-3.2 (English) or simba-3.0 (the languages it covers) — the endpoint and request shape are otherwise unchanged. Already-generated audio is unaffected. Not ready to switch the model string by 2026-09-21? Pin Speechify-Version to a date before 2026-09-21 and both ids keep responding — see Buy time by pinning your API version. Need a language simba-3.0 does not yet cover? Talk to us.

What is changing

Withdrawal is two dated steps, both published up front:

When	What happens
From API version `2026-09-21`	The pair is no longer selectable: naming either model returns `400 model_retired`, and neither appears in `GET /v1/audio/models`. New workspaces are pinned at signup, so they can’t select it at all.
From `2026-11-21`	Both ids keep answering on every API version that can still name them, served by our current models instead of their Simba 1.6 training: `simba-multilingual` by the multilingual model, `simba-english` by `simba-3.2` for English and the multilingual model otherwise.

2026-11-21 is the date the audio changes for everyone still naming the pair, pinned or not. Nothing breaks, but the voice will not sound exactly as it does today. Two differences to plan for: SSML <prosody pitch>, <prosody volume>, <emphasis> and <speechify:style emotion> are not applied by the current models (breaks and <prosody rate> are), and a voice you tuned on Simba 1.6 is rendered by a different model.

Are you affected?

You are affected if a synthesis request sends model: "simba-english" or model: "simba-multilingual" to POST /v1/audio/speech or either /v1/audio/stream route.

You are not affected if you name simba-3.0 or simba-3.2, or omit model entirely — an omitted model resolves to simba-3.0, which is unchanged.

Where to go

From	To	Notes
`simba-english`	`simba-3.2`	English; lower time-to-first-byte and richer expressivity. Takes every English voice in the catalog, cloned voices included.
`simba-multilingual`	`simba-3.0`	Covers the locales most multilingual traffic actually uses (see below), streaming-native and lower latency. Accepts the full voice catalog, including your cloned voices.

For most integrations this is a one-line change — swap the model string and keep everything else — but check two things first:

Non-English voices on simba-3.2. simba-3.2 is English-only: it takes every English voice in the catalog and your own clones, but a non-English voice is rejected because there is no multilingual training to route it to. Move those integrations to simba-3.0, which serves every voice in every supported language.
Omitting language. On simba-multilingual, leaving language out auto-detects the language from your input text. simba-3.0 instead falls back to the voice’s own locale. If you rely on detection, set language explicitly on the request when you move.

{
  "input": "Hello from Speechify.",
  "voice_id": "your-voice-id",
  "model": "simba-3.2"
}

POST

/v1/audio/speech

from speechify import Speechify
client = Speechify(
    token="YOUR_TOKEN_HERE",
)
client.audio.speech(
    audio_format="mp3",
    input="Hello! This is the Speechify text-to-speech API.",
    model="simba-3.2",
    voice_id="geffen_32",
)

Try it

Check your languages first

Most workspaces on simba-multilingual synthesize only English, German, Spanish, French, Italian or Brazilian Portuguese — all covered by simba-3.0. If that is you, simba-3.0 covers it today — set language explicitly on the request (see the note above on omitting it) and the switch is a one-liner.

If you synthesize outside that set, broader multilingual coverage is landing on the current model generation before 2026-11-21, and it is the model simba-multilingual is served by from that date, so those languages keep working. Talk to us if you want to test it earlier.

Buy time by pinning your API version

2026-09-21 is the cut-over. From that API version, naming either model returns 400 model_retired, so send Speechify-Version set to a date before 2026-09-21 on your synthesis requests to keep simba-english / simba-multilingual on their Simba 1.6 training until 2026-11-21. The official SDKs expose this as a version option; and because a workspace’s stored default only ever moves forward, the per-request header is how you hold an older shape. See API Versioning for how to read and set it.

While your workspace is pinned below 2026-09-21, both models still appear in GET /v1/audio/models carrying retired_at: "2026-09-21" and sunset_at: "2026-11-21". Read sunset_at for the day the model behind the id changes.

The pin holds Simba 1.6 until 2026-11-21, whatever you pin; from then the ids are served by our current models.

Migration checklist

Find where you name the models

Search your integration for simba-english and simba-multilingual. Requests that omit model are already on simba-3.0 — no change needed.

Pick the replacement

simba-english → simba-3.2 for English, or simba-3.0 if the voice is not English. simba-multilingual → simba-3.0 if your languages are in its set; otherwise talk to us.

Swap the model string and test

Change the model value and re-run your synthesis. The endpoint and request shape stay the same — just confirm your voice is accepted on simba-3.2 (or use simba-3.0), and set language explicitly if you were relying on auto-detection.

If you need longer, pin instead

Set Speechify-Version to a date before 2026-09-21 to keep the Simba 1.6 training until 2026-11-21 while you plan.