Spark TTS vs AudioLDM 2: Which AI Model Should You Choose?

Pricing, context windows, latency, capabilities, and a one-line code switch — everything you need to pick the right model.

Replicate
Text-to-Speech
vs
Replicate
Text-to-Speech
Verdict

Spark TTS and AudioLDM 2 are closely matched on pricing and context. The right choice depends on your specific workload — see the table below for the full breakdown.

Side-by-side specs

SpecSpark TTSAudioLDM 2
ProviderReplicateReplicate
CategoryText-to-SpeechText-to-Speech
Input cost / 1M tokensn/an/a
Output cost / 1M tokensn/an/a
Context window——
Max output tokens——
Avg. latency——
Featured——
New——
Capabilities
text
audio
text

Pricing example

A typical chat workload of 100,000 input tokens plus 50,000 output tokens.

Spark TTS
n/a

100K in × n/a + 50K out × n/a

AudioLDM 2
n/a

100K in × n/a + 50K out × n/a

Switch in one line

Both models live behind Railwail's OpenAI-compatible endpoint. Replace the model string and you are done.

JavaScript / TypeScript
import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.RAILWAIL_API_KEY,
  baseURL: "https://railwail.com/v1",
});

// Before — using Spark TTS
let r = await client.chat.completions.create({
  model: "jichengdu/spark-tts",
  messages: [{ role: "user", content: "Hello" }],
});

// After — switched to AudioLDM 2
r = await client.chat.completions.create({
  model: "haoheliu/audio-ldm",
  messages: [{ role: "user", content: "Hello" }],
});
Python
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["RAILWAIL_API_KEY"],
    base_url="https://railwail.com/v1",
)

# Before — using Spark TTS
r = client.chat.completions.create(
    model="jichengdu/spark-tts",
    messages=[{"role": "user", "content": "Hello"}],
)

# After — switched to AudioLDM 2
r = client.chat.completions.create(
    model="haoheliu/audio-ldm",
    messages=[{"role": "user", "content": "Hello"}],
)
cURL
# Before — using Spark TTS
curl https://railwail.com/v1/chat/completions \
  -H "Authorization: Bearer $RAILWAIL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "jichengdu/spark-tts",
    "messages": [{"role": "user", "content": "Hello"}]
  }'

# After — switched to AudioLDM 2
curl https://railwail.com/v1/chat/completions \
  -H "Authorization: Bearer $RAILWAIL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "haoheliu/audio-ldm",
    "messages": [{"role": "user", "content": "Hello"}]
  }'

Which one wins for...

Quick verdicts derived from public specs. Always validate on your own workload.

Coding
Spark TTS

Higher coding category match or larger context wins.

Writing
Spark TTS

Bigger context window helps maintain long-form coherence.

Long documents
Spark TTS

The larger context window is the deciding factor.

Vision
Tie

Multimodal/vision support is required for image inputs.

Real-time chat
Tie

Lower average latency wins for interactive UX.

Cost-sensitive
Tie

The model with the lower input-token price wins.

Frequently asked questions

Which is cheaper, Spark TTS or AudioLDM 2?
Spark TTS and AudioLDM 2 cannot be compared on per-token price: at least one of them has no per-token price listed (it is priced per run or not yet priced). See each model page for its current price.
Which has more context, Spark TTS or AudioLDM 2?
Spark TTS and AudioLDM 2 have similar context windows (— vs —).
Is Spark TTS better than AudioLDM 2 for coding?
For coding-heavy workloads we lean toward Spark TTS on this comparison — it scores higher on the relevant heuristics (category, tags, or context window). Both models are usable for code via Railwail's OpenAI-compatible endpoint, so the safest path is to A/B test on your own prompts.
Can I use both Spark TTS and AudioLDM 2 via Railwail?
Yes. Both Spark TTS and AudioLDM 2 are accessible through a single Railwail API key and the OpenAI-compatible /v1/chat/completions endpoint. You only change the "model" parameter to switch between them — no SDK swap, no separate billing.
How do I switch from Spark TTS to AudioLDM 2?
Replace the model identifier "jichengdu/spark-tts" with "haoheliu/audio-ldm" in your request payload. Everything else — API key, base URL, request shape — stays the same. See the code example on this page for the exact one-line change.

Try Spark TTS and AudioLDM 2 side by side

One API key, one endpoint, both models. Start free — no credit card required.