It all began in a bar. One night, the wife of Growlers’ Brooks Nielsen ran into Julian Casablancas and began talking about her significant other’s longtime garage rock group to The Strokes frontman. “We had played with him a long time ago, so there was an initial little friendship and then that was it,” explains Nielsen.

The Growlers ended up working with Casablancas on “City Club,” which comes out Sept. 30 on his label Cult Records. We spoke with lead singer Nielsen on working with Casablancas, how the record came together and writing at keyboardist Kyle Straka’s ranch house in California’s Topanga Canyon.

What was working with Julian like?
It was different. I’ve never given up that much control … He’s a melody man. He got hands-on with a handful of songs and it was cool.

How did the title track come together?
[Casablancas] had heard two songs that we had and wanted to connect — just keep the verse from one song and the chorus from the other and kind of cut them and put them together. He kind of tried them on the computer — there was a lot of computer work, which I wasn’t used to.

Producing so much of the songs digitally must have been bizarre.
Yeah, it was really weird for us. We’ve done that with making demos and stuff a little bit, but not really to that extent … We’re used to making the record in more of like a hands-on, rock ’n’ roll approach. But it opened up some avenues, made some things happen that I don’t think would’ve happened otherwise.

What were you trying to do on the record?
Matt [Taylor, the lead guitarist] wanted to go more into a synth world and more away from the stereotype we’ve been living in for a long time: beach goth. We just kind of wanted to expand a bit musically. Matt and I have always wrote the bulk of the music. There’s nothing different in that regard. We did it in the same way that we’ve done before too, which is cut ourselves off from everybody we know and go up into Topanga Canyon and just really focus on just making music. We wrote about 70 songs and narrowed it down.

You guys are known for pretty exhilarating live shows. Do you have anything specific planned for the upcoming tour?
All in all, we’ve spent more time in the rehearsal studio in a serious manner than we have before. I’m excited to go out there. I think it’s going to be the strongest Growlers anyone’s ever heard. Just go out there and have as much fun as we can and just make that s— contagious.