TTS API comparison 2026
Gradium TTS Beta vs Deepdub Phantom Z 3.4 conversational Gradium vs Deepdub · text-to-speech for voice agents
Gradium TTS Beta ranks 1st of 112 with 76.8/100; Deepdub Phantom Z 3.4 conversational ranks 22nd with 33.9/100: a gap of 42.9 points on the same public rules, built on Coval, Speko and Artificial Analysis.
Data checked on September 30, 2026 · Coval 30-day window ending October 1, 2026 · updated after each benchmark capture
Side-by-side benchmark
| Measure | Gradium TTS Beta | Deepdub Phantom Z 3.4 conversational |
|---|---|---|
| Overall score | 76.8/100 | 33.9/100 |
| Rank | 1st of 112 | 22nd of 112 |
| Real-time speed /60 | 58.7 | 33.3 |
| Voice quality /20 | 7.8 | 0 |
| Accuracy /15 | 9.8 | 0.6 |
| Price /5 | 0.5 | 0 |
| P50 / median time-to-first-audio Coval, 30-day window | 47.2 ms | 261.3 ms |
| P99 time-to-first-audio (slowest turns) Coval, 30-day window | 108.8 ms | 427.4 ms |
| Latency consistency (standard deviation) Coval, 30-day window | 16.6 ms | 80.8 ms |
| P50 time-to-first-audio, US East Speko | 100 ms | not measured |
| Accuracy: word error rate (WER) Coval, 30-day window | 4.5% | 5.8% |
| Pronunciation robustness (0 to 1) Speko | 0.3 | not measured |
| Speech Arena Elo (blind listener preference) Artificial Analysis | not measured | not measured |
| Naturalness (Elo) Speko | 1579 | not measured |
| Price per 1M characters Artificial Analysis | not measured | not measured |
Choose Gradium TTS Beta if…
- → Ranks 1st of 112 in the overall benchmark, against 22nd for Deepdub Phantom Z 3.4 conversational
- → Better P50 / median time-to-first-audio: 47.2 ms vs 261.3 ms (Coval, 30-day window)
- → Better P99 time-to-first-audio (slowest turns): 108.8 ms vs 427.4 ms (Coval, 30-day window)
- → Better latency consistency (standard deviation): 16.6 ms vs 80.8 ms (Coval, 30-day window)
- → Better accuracy: word error rate (WER): 4.5% vs 5.8% (Coval, 30-day window)
Choose Deepdub Phantom Z 3.4 conversational if…
On the published benchmarks, Deepdub Phantom Z 3.4 conversational wins none of the measurements above against Gradium TTS Beta. This says nothing about features the benchmarks do not measure.
Deepdub Phantom Z 3.4 conversational: all measurements →Frequently asked questions
- What is the difference between Gradium TTS Beta and Deepdub Phantom Z 3.4 conversational?
- In the 2026 TTS API benchmark, Gradium TTS Beta ranks 1st of 112 with 76.8/100 and Deepdub Phantom Z 3.4 conversational ranks 22nd with 33.9/100, a gap of 42.9 points on the same rules.
- Which is faster for real-time voice agents, Gradium TTS Beta or Deepdub Phantom Z 3.4 conversational?
- On Coval's 30-day window ending October 1, 2026, the P50 time-to-first-audio is 47.2 ms for Gradium TTS Beta and 261.3 ms for Deepdub Phantom Z 3.4 conversational; the P99 is 108.8 ms and 427.4 ms.
- On which criteria does Deepdub Phantom Z 3.4 conversational beat Gradium TTS Beta?
- On the 4 criteria of the benchmark, Deepdub Phantom Z 3.4 conversational scores higher on none.
- How are these two text-to-speech APIs scored?
- Both are scored by the same public rules: 4 criteria, 100 points (Real-time speed 60, Voice quality 20, Accuracy 15, Price 5), computed from three independent benchmarks: Coval, Speko and Artificial Analysis. A measurement a benchmark does not publish counts zero, and the model page says why.
- Can these numbers be checked?
- Yes. Each model page lists every measurement with its source and date, and links to the benchmark page it comes from. The rules are on the methodology page.