The Wilders aren’t what they used to be.

They’re still a foursome whose repertoire includes fiddle tunes, murder ballads and old-time love songs. And they’re still performing at places like the Old Town School of Folk Music in Chicago or events like the annual bluegrass festival in Skiatook, Okla.

But change is overcoming one of Kansas City’s best-known classic-country bands, and the evidence is all over the Wilders’ new album, “Someone’s Got to Pay.”

One clue: In the portrait on the inside sleeve, the band members are dressed in their street clothes instead of the usual Western stage garb. The liner notes give away another surprise: Electricity has come to the Wilders’ world, so have the beat of many drums and the sound of pianos. And unlike any other Wilders album, every song on “Pay” was written by someone in the band.

This change isn’t dramatic, like Dylan going electric or Metallica cutting its hair, but it is significant.

“What we wanted to do is record our own songs,” fiddler Betse Ellis said. “But we also wanted to go beyond what we’ve always done, which is take these, like, Hank Williams songs and throw them into the Wilders’ machine and see what comes out. We wanted to grow as a band.”

The lines between routines, habits and ruts can get murky, and within the Wilders camp those lines had started to disappear. Asked whether anything in particular prompted the change, Ellis and Phil Wade (guitar, mandolin, banjo) say, almost in unison, “Nate started it.”

He is Nate Gawron, bass player, and in the credits to “Pay,” he plays his usual acoustic bass on seven tracks. On four others, however, his bass is plugged in.

“Essentially Nate said, ‘I think we should start doing some original stuff or I’m going to quit,’ ” Wade said. “At first we were a little freaked out. But after a while it started to make sense.”

“If anyone’s going to get bored in a string band,” Ellis said, “it’s the bass player. We’re not a jazz string band. There aren’t that many chord changes.”

Ike Sheldon, the band’s lead vocalist and rhythm guitar player, had other rationales: The band’s previous albums, he said, were like snapshots of their high-energy live shows.

“I like all our old records,” he said. “But they never quite translated what we were doing on stage. They never really captured that energy. We finally decided we had to do something else to raise the energy of our albums. How? Let’s have more variety, more sound, more energy.”

“Pay” isn’t the first Wilders album with original material. The band recorded its own songs on “Spring a Leak,” released in 2005. But only half of the songs on “Leak” were originals, and they stuck pretty closely to the band’s usual old-time arrangements. So even with the original material, “Leak” didn’t sound much different from other Wilders albums.

“When we first started playing our own songs, it would be only if we’d decided they could hold their own,” Sheldon said. “If somebody had written one, we’d ask, ‘Can I sing it after “Hey, Good Lookin’ ” and before “Ring of Fire”? Can it hang with our other material?’ ”

Even with their own material, the Wilders were still a band with a signature sound and the fashions to go with it. For better or worse, they’d become pigeon-holed.

Ellis said, “We began to realize that some people were beginning to think of us as a novelty act. I can understand that. We were serious about what we were doing, but at the same time we were acting goofy and not worrying about things getting a little messed up on stage.”

“We were at a bluegrass conference,” Wade said, “and someone expressed doubt about hiring us for a festival because they were like, ‘They only do that classic country thing. What are they really doing?’ That raised an issue with me. I thought in order to take the next step, maybe we should do our own songs.”

Sheldon said the shift in sound that is so evident on several tracks on “Pay” isn’t an attempt to get out of being branded a novelty act. Rather it’s a way to “stretch out.” He sees the process as a natural graduation. After years of honoring the traditional classics and standards, the Wilders are ready to craft their own sound.

“We learned how to play country music by playing the masters — Hank Williams, Johnny Cash,” he said. “We learned how that stuff works, and it’s been great fun doing it. But now it’s like our apprenticeship is over. It’s time to go to the next step.”

No song on “Pay” exhibits the band’s thirst for change more than the closer, “Goodbye (I’ve Seen It All).” Sheldon added the song to the album late — very late. “Not the 11th hour,” Ellis said, “more like the 11th hour and 58 minutes.”

Sheldon said the piano interludes were actually added later than “Goodbye” but agreed that, yes, the album’s most distinct song, written and crafted during the mixing process, barely made it on the album.

“Goodbye” is a bouncy indie-pop tune with ’60s pop-vocals and handclaps and tambourines and an invigorating acoustic guitar solo by producer Brendan Moreland that is very early Beatles. It sounds like the Hollies via Memphis in the late ’50s. It also sounds like something that will surprise — pleasantly or not — Wilders purists.

“If people like it, that’s cool,” Sheldon said, “if not, that’s cool, too. I don’t mean to sound callous, but I really don’t care. We just wanted to make a good record and were proud of it. It’s the first Wilders album I’ll listen to myself. The others? I hear them every night.”

For tonight’s CD-release party at Crosstown Station, the Wilders have hired a drummer to help re-create some of the sounds of the new album: T.C. Dobbs of Rex Hobart & the Misery Boys. Sheldon said he’s not exactly sure how the band will pull off the new stuff. He lives in Pennsylvania now with his wife, so the Wilders don’t rehearse like they used to.

“We’ll figure it out,” he said, chuckling. “We’re still experimenting.”

Tonight’s show is the first of a spring and summer tour that will take the band around the United States and over to Scotland and Ireland. One place they won’t be going, for the first time in several years: the bluegrass festival in Winfield, Kan. — another sign of the changing times.

“They want to switch things up,” he said. “People had been complaining that it was getting too stagnant. We were one of the ones who got cut. But we understand. We’ve played it like six or seven years in a row. Unless you’re like Doc Watson at Merlefest, no one does a festival that often.

“We’re going to miss it. It has been a part of our lives for so many years. We hope they’ll give us a year’s break and then have us back.”

If anyone who runs Winfield had heard “Someone’s Got to Pay,” they might have had them back this year: These Wilders aren’t the same as last year’s.

-- by Timothy Finn