More than 30 years ago, a cadre of musicians holed themselves up in a

two-bedroom dump of a house in Woodlawn Hills, north of Los Angeles.

For nine months they stayed there. Together.

Their diet focused heavily on soybeans.

When they emerged, Captain Beefheart and His Magic Band had created the

music for one of the most influential albums in rock history: Trout

Mask Replica.

"Recording was secondary to a typical day -- a typical day was get up

and work on parts," said guitarist Bill Harkleroad, credited on the

album as Zoot Horn Rollo. "We'd work on practicing individual parts, and

then work as a group putting them together. Anywhere from a short day

of 10 hours to a long day of 16 hours. Every day."

Musicians by the droves -- from the Clash's Joe Strummer and Talking

Heads' David Byrne to Thurston Moore of Sonic Youth, Kurt Cobain and

countless others -- have acknowledged the profound influence of Trout

Mask Replica.

To the uninitiated, the album's experimental rhythms and fractured song

structures seem like spontaneous sonic and verbal emissions. But devotées

revel in the disc's idiosyncratic, off-the-wall fusion of blues, jazz,

rock and the avant-garde. Musical myth and legend have risen up out of

its sophisticated arrangements and their creation.

Now a window into the grueling hothouse process will be opened May 18

when Revenant Records issues a five-CD box set, Captain Beefheart &

His Magic Band Grow Fins, Rarities 1965-82. The groundbreaking

release will contain an entire CD of what are known in Beefheart

collectors' circles as "The House Sessions" -- early, vocal-less

recordings of the songs that were later captured in the studio as

Trout Mask Replica.

"It shows that this stuff -- which is often thought of as chaotic and

improvised -- is actually highly composed," said Dean Blackwood, co-owner

of Revenant with musician John Fahey. "It's unconventional music without

a doubt, but every note has its place."

In addition to the House Sessions, Grow Fins includes dozens of

demos and live songs unearthed from original Magic Band members -- many

of which have never been heard outside the band -- as well as video

footage, on an enhanced CD, spanning the years 1968 to 1973. It also

features a 120-page hardcover book with extensive liner notes penned by

Magic Band drummer John French (a.k.a. Drumbo).

Always an elusive figure, Beefheart (Don Van Vliet), 58, turned his back

on the music world in the early 1980s, apparently for good, to

concentrate on painting. Numerous attempts to contact him for input on

the box set went unanswered, although Revenant does have an address where

they can send him royalties, Blackwood said.

"The original idea [for Trout Mask Replica] was that these would

be more like field recordings, because that's how the band was viewed,

as this sort of curiosity," he said. "It was like going into the bush to

make field recordings in Australia, like, 'Let's catch these people in

their element.' It was a very strange element, but it's theirs."

Harkleroad, 50, recently published a book on his tenure with the band

called "Lunar Notes: Zoot Horn Rollo's Captain Beefheart Experience."

Now a music teacher beginning to record under the Zoot Horn Rollo

moniker again, Harkleroad described the House Sessions as a fatiguing

mixture of chaos, composition and emotional toil that he calls "my

Vietnam."

Different songs, of course, had different origins. Some tracks were

based on whistled parts from Beefheart. Others, such as

"Pachuco Cadaver"

(RealAudio excerpt) and "Sugar and Spikes"

(RealAudio excerpt) were originally grounded in keyboards.

"Don would sit down and play a part on the piano, and John [French]

would get him to repeat a figure, and then John would record it and

notate it," Harkleroad said. "And then that was cataloged. Then John

would work them out with the bandmembers. When John would ask, 'Who

plays that?' or 'Where does this go?' Don would look at him and say,

'You know.' "

The fruits of that intricate process continue to inspire.

"Trout Mask Replica completely changed how I listened to music,"

said experimental composer and Gastr del Sol member Jim O'Rourke, 29,

who also has worked with Sonic Youth and Red Krayola.

"I had never heard anything in my life with that kind of rhythmic

concept ... Somebody's line is five beats long, somebody's line is

seven-and-a-half beats long, but it's all relating to this pulse. ...

As a kid I thought they were playing whatever came to mind. Then I

started to notice how particular what they were playing was, and how

specific. I started listening to how the parts related."

While the House Sessions and video footage will to many listeners be the

keystones of Grow Fins, the collection touches on each period of

Beefheart's career. From the period marked by the albums Doc at the

Radar Station (1980) and Ice Cream for Crow (1982) come two

versions of the song "Evening Bell." The first is an impossibly complex

piano version recorded by Beefheart for guitarist Gary Lucas to learn.

The second take is Lucas' guitar interpretation.

"I found it very daunting," said Lucas, who more recently has recorded

with bluesy rock singer Joan Osborne and the late rock singer/songwriter

Jeff Buckley. "It was beautiful music, but it was all dense and knotty

and composed on piano. My job was to transcribe it by ear for guitar.

And I said, 'Hey man, you're using all 10 fingers on the piano and there's

only six strings on a guitar.' So he said, 'You better find another

four.' "

"I really believed that we were doing something monumentally different,

and that I was fortunate in that way," recalled Harkleroad of his time

in the band. "And I knew how hard I was working. What the hell else was

I going to do?"