The angel investor who backed a billion-dollar AI startup when it was still in its infancy said he decided to invest in the company after just 30 minutes of meeting one of its founders.

Carles Reina first decided to invest in AI voice startup Eleven Labs in 2022, when he was a venture partner at pre-seed fund Concept Ventures.

Co-founded in 2022 by Mati Staniszewski and Piotr Dąbkowski, Eleven Labs specializes in advanced text-to-speech and voice cloning technology. In its January Series C funding round earlier this year, the company raised $180 million at a valuation of $3.3 billion.

Then, in September, the company announced it would allow employees to sell shares valued at $6.6 billion.

However, before Eleven Labs even had a concrete product, Reina, who was working at Palantir Technologies at the time, decided to take a chance on the company after meeting Staniszewski.

“I met Mati when I was still at Palantir,” Reina told CNBC Make It in an interview. “We started talking and, 30 minutes into the first conversation, I said, ‘How much money do you want?'”

Reina explained that before the launch of ChatGPT, voice AI hadn’t attracted much attention because big tech companies like Google, Amazon, and Microsoft had text-to-speech products, but they hadn’t really taken off.

“With ElevenLabs no one was looking at voice AI, literally no one wanted to give [them] money. No VC wanted to back ElevenLabs, in the early days of the pre-seed round. “So those are the kind of industries I really like, so I can get in before everyone else,” he said.

Reina has made 74 angel investments in the last eight years, including Revolut, Volumetric, Elroy Air and Speckle. He now works for Eleven Labs as a marketing manager.

He said he always tries to identify industries that other investors don’t pay attention to: “I’ve done [invested in] mainly AI before it was sexy. I’ve done robotics before it was sexy too.”

Reina specializes in investing in pre-seed companies: those with an idea, but often without a fully developed product. This means identifying key traits in founders that indicate a startup will be successful.

“If there’s a product, great, but if there’s no product, absolutely fine with me… I love founders who are very technical. They’re super sharp, very smart, and they’re literally trying to build a global company from day one,” Reina explained.

He said he “invests based on a thesis,” so if a founder is very technical, they will have a deeper understanding of the product and the market they sell to.

Reina said he saw these traits in Staniszewksi, which convinced him to back ElevenLabs even though the voice AI market was very small at the time.

“No one wants to talk to AI voices if they sound robotic. That’s fundamentally the biggest problem there was… so when I spoke to Mati, he talked about both elements, and he hadn’t been on the market,” Reina said.

“It was really interesting to see that he was thinking about ecosystem-wide problems before he even had any product or even before he talked to an actual potential customer.”

Staniszewski had a background in mathematics and gained a first class honors degree from Imperial College London. His vision and technical expertise sold Reina, and ElevenLabs became one of the few startups he decided to back “literally in less than an hour.”

Now, Eleven Labs is planning a global expansion, including building new centers in Paris, Singapore, Brazil and Mexico, as well as preparing the company for its initial public offering (IPO) in the next five years, Staniszewski told CNBC in July.