Even Pig Iron co-artistic director Dan Rothenberg scratches his head when asked to describe “Swamp Is On,” the new collaboration between the inventive theater company and Philly psych-rock eccentrics Dr. Dog. “I’m calling it a few different things,” he begins. “One is a concept album brought to life. Another is… let’s see.”

After a moment, he brings up those TV commercials that place cars or bicycles into laboratory settings, where white-coated scientist types with clipboards put them through efficiency or stress tests. “Now imagine,” he continues, “that it’s a rock band instead of an Olympic cyclist. The rock band’s transmissions are being collected by scientists on stage and turned into new sounds. All those vibrations come together and create an otherworldly rock and roll show.”

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If that doesn’t exactly clarify what to expect at the new show, which will occupy Union Transfer for four nights as part of the Fringe Festival, that’s par for the course for Pig Iron. The company routinely creates theatrical happenings that are easier and far more exhilarating to experience than explain. (And if all else fails, Dr. Dog will follow each evening’s performance with a full set, as if, Rothenberg says, “Dr. Dog in disguise is opening for Dr. Dog.”)

The show plays on a bit of Dr. Dog mythology, in which the band claims to have received a mysterious cassette tape from another world called the Psychedelic Swamp. The Pig Iron Psychedelic Signals Auxiliary is asking audience members to bring in old cassette tapes that they can afford to see destroyed in order to help commune with the swamp, a reminder of a time before music became digital.

“Music is losing its physicality,” Rothenberg says, “and you could say that about a lot of different aspects of live entertainment. There’s a handmade quality to the Pig Iron aesthetic and the Dr. Dog aesthetic, which that is part of what we really love about them and we’re evoking in the show. We’ll be doing video live onstage, but instead of making slick, beautiful videos of the band, we’re going to be video-ing tiny, handmade objects. That’s part of this tactile feeling that I think will be unique to this event.”

No lava lamps here

If the word “psychedelic” conjures worrying images of tie-dye and lava lamps, fear not: both Pig Iron and Dr. Dog are hoping to expand the audience’s conception of the term. 

“Dr. Dog really push against a cliché idea of the word ‘psychedelic,’” Rothenberg says. “They told us that Pig Iron is psychedelic, and when we pushed them on that they said it’s more about seeing something in one way and then moving to a place that you didn’t imagine and seeing it from another perspective. 

“We love that, too; we love to take a moment on stage and turn it around to show you the back side of the moment.”

The details

"Swamp Is On"

Sept. 9-12, 8 p.m.

Union Transfer

1026 Spring Garden St.

$30, 215-413-1318

Fringearts.com