NEW YORK (NYTIMES) - Comedian Dave Chappelle used to hate when fans would pull out smartphones during his act, record the performance and then post it on YouTube and social media before the show had even ended. To him, the fans seemed more interested in getting the perfect shot than in appreciating his stand-up routine.
But in late 2015, Chappelle discovered a technology called Yondr. Fans are required to place their cellphones into Yondr's form-fitting lockable pouch when entering the show, and a disc mechanism unlocks it on the way out. Fans keep the pouch with them, but it is impossible for them to snap pictures, shoot videos or send text messages during the performance while the pouch is locked.
"I know my show is protected, and it empowers me to be more honest and open with the audience," Chappelle said by e-mail.
After his first phone-free performance, Chappelle was sold, and now he insists on deploying Yondr at all of his shows.
Other entertainers have since used Yondr, including Alicia Keys; Guns N' Roses; Maxwell; and the actor, musician and comedian Donald Glover, who goes by the stage name Childish Gambino. Some have employed it for special listening parties, festivals or one-off shows; others, like Chappelle, have used it for entire tours.
Of course, an artist or venue can always state that cellphone use is not permitted and trust fans to comply. But often people rebel.
A phone-free event "is a very different experience," said Mr Graham Dugoni, who founded Yondr.
Mr Chad Taylor, who manages Glover, among others, said: "It's hard to meet people in the room when you're busy texting friends who aren't there."
He added: "It's hard to enjoy a concert experience when you're looking at it through an iPhone camera and trying to get the best shot."
When the rocker Axl Rose reunited with his former Guns N' Roses bandmates, Duff McKagan and Slash, for the first time in 23 years, the concert was phone-free.
"God, it was wonderful," McKagan said of the first reunion show in April, at the Troubadour in Los Angeles. "It was the old-school feeling, where people were dancing and getting down. It was really cool."
It was far different from a concert he did with his other band, Loaded, a few years ago in Córdoba, Argentina. "I started playing, and I was staring into a sea of iPads and bright lights," he said.
He abruptly stopped the show and asked people to put their devices down, at which point the show improved vastly, he said.
Lesser-known bands might be more hesitant to try Yondr, as many rely on fans posting photos and videos to promote their shows.
And some fans object to not being able to disseminate and see live shows.
"If there were no cellphones, and you couldn't capture any video, it would be disappointing," said Mr Steve Dintino, a Philadelphia music fan, who videotapes every concert he attends.
He started filming shows in 1994 after attending a Frank Sinatra concert in Atlantic City, where he yelled "I love you Frank" from the front row, and Sinatra responded: "I love you too, pal."
A friend recorded the show, and "so I have the audio of that concert". Ever since then, "I try to capture every concert that I go to in some capacity," he said.
"The ability to see it happening live" from the comfort of your living room "is incredible", said Mr Chris Kooluris of Manhattan, a hardcore music fan who has been to dozens of live shows and watched others online through Periscope, Twitter's video feature.
"I stayed up all night long looking for periscope feeds from the Guns N' Roses show in LA," Mr Kooluris said. But when attending live shows, Mr Kooluris said he prefers to see fewer cellphones. To resolve this issue, he suggests that bands allow one person to videotape the show and then give ticket holders access to the feed afterward.
But Yondr is not just for concerts. The company has been renting its devices to schools, restaurants and wedding venues, and to movie studios for pre-screening events, in the United States and abroad. In the future, it could also be used during "live" theatre performances, at sporting events such as golf tournaments, and in spas and movie theatres, Mr Dugoni said.
Mr Dugoni, 29, was born in Portland, Oregon, where his father is a physician and his mother is a homemaker. After graduating from Duke University with a degree in political science in 2009, he took a series of jobs - teaching English in Vietnam, playing soccer in Norway in 2010, working at investment advisory firms in Portland and Atlanta, and joining a virtual currency startup, which failed, in San Francisco in 2013.
Throughout his 20s, Mr Dugoni became increasingly aware of - and annoyed with - the way people were glued to their cellphones as face-to-face social interaction took a back seat.
He also saw issues with smartphones and privacy. "At a festival at Treasure Island in San Francisco in 2013, I saw some guy dancing pretty drunk and saw two strangers recording the guy, and they posted it to YouTube without the guy's knowledge," he said.
With US$15,000 in his pocket, Mr Dugoni set out to build Yondr. He spent about six months sketching designs, experimenting with 40 fabrics and locking devices, visiting hardware stores, and consulting with manufacturers in China before developing a prototype in 2014.
But getting seed money to manufacture Yondr was a challenge. Silicon Valley investors thought the idea of phone-free events was preposterous and almost laughed him out of the room.
"They just didn't get it," he said. Undaunted, he turned to his hometown, where he raised US$100,000 from angel investors.
"I thought the idea had legs and great market potential," said Mr Tony Arnerich, one of Yondr's investors and a longtime family friend. The company raised an additional US$75,000 in 2015.
Yondr makes money by renting the devices for US$2 a case each day, although it offers discounts for large quantities or for schools that use them for extended periods.
The company's first paying job was in mid-2015, and within six months it had turned a profit, Dugoni said. The technology has been used in 57 venues and 300 schools in 2016, up from five venues in 2015.
Comedy Works, which has showcased such comedians as George Lopez and Wanda Sykes, has been using Yondr devices at its two clubs in Denver since May.
"All of the big artists have said: 'Wow. Thank you. This is amazing,'" said Ms Wende Curtis, the owner. Patrons have asked if they could buy the device for their homes, she said.
The company only rents the devices now, but is considering selling them in the future.
Some fans have been disgruntled. A few demanded refunds rather than give up their phones, Ms Curtis said. "And one drunken party of eight got 'nasty' and posted complaints on social media," she said.
At a Dave Chappelle show, one inebriated fan chewed through the bottom of the pouch, recalled Mr Corey Smyth, chief executive of Blacksmith Records, who works with Chappelle among others.
The pouch allows phone signals to get through, so someone can feel a phone vibrate when a message arrives. Anyone who needs access during a show may leave the room, have the device unlocked and use the phone in the lobby or outside - similar to the way smokers light up outside a non-smoking theater.
"Some venue staff have access to their phones at all times inside the space," Mr Dugoni said, in case of an emergency.
Yondr is not a fad; it is the wave of the future, Mr Dugoni said.
"I view it as a social movement, and this is one piece of the puzzle," he said. "It's about helping people live in the digital age in a way that doesn't hollow out all of the meaning in your life."