In the first of a two-parter John Morrish takes Brian Wilson from the surf-board to the mixing-board, and points to "Today" as the key Beach Boys record of the period.

Brian Wilson, the man who made the Beach Boys the most advanced American group of the 1960s, has always been an enigma, even to those who should know him best. "The thing I wonder about is where does Brian's creative spark come from?" asked his brother Dennis in Timothy White's "Crawdaddy" study. "Not his subjects or anything, but his spark. What makes it so great for me is that I really don't know. There's a mystery behind Brian, even to me."

In truth, there are two mysteries, or rather two halves of a single mystery. How did a college drop-out of modest intellectual accomplishments rise from bashing out three chord rock'n'roll to creating some of the most complex orchestral and vocal arrangements ever put on vinyl? And how did that same college dropout-cum-master-producer then allow the whole thing to slip away, as quickly and mysteriously as it came?

Brian is unique among the producers featured in this series in that all his success came with a single group of performers, the band he formed, played in and sang with: the Beach Boys.

Under Brian's guidance, the band established the right of a rock'n'roll group to take charge of its own creative work. He won the right to produce the band himself, to choose the studios he liked, to pick his songs, and eventually to have the band's own record label.

As a producer, Brian had not one style but a succession of styles reflecting his own progress. We see his work fall into three periods. From "Surfer Girl" to "Today", he was learning the skills. From "Today" to "Pet Sounds" he was putting those skills to work, and going further than anyone had before. Then, from the "Good Vibrations" sessions to, say, "Holland" we see him reach first an astonishing peak of creativity and then fade away into obscurity and semi-retirement. A burst of "occupational therapy", producing the albums "15 Big Ones" and "The Beach Boys Love You", provides a hopeful coda to the story.

1963's "Surfer Girl" was Brian's first accredited production, though it was certainly not the first time he had been in charge in the studio. It provided the first glimpses of what the future would hold. It is crisply and cleanly recorded, and everything is on key. That in itself was a major step forward.

But what strikes the listener are the harmonies, lush and full, clearly derived from such white harmony groups as the Four Freshmen, but with an unusual nasal quality derived from the extreme youth of some of the participants, for instance the 17-year-old Carl Wilson. Some listeners claim that the unusual consistency of the harmonic blend comes from the fact that three of the band were brothers and the fourth a first cousin.

Clearly Brian had an early aptitude. Numerous writers have questioned Brian's parents and brothers and have all got the same answer: even as a young child he had perfect pitch and was not ashamed of showing off his voice. He had two months of accordian lessons, then gave up and concentrated on teaching himself piano and organ.

That was no good for a 1961-style rock group, so in the three days before their first real gig Brian taught himself to play the bass (at least according to Carl Wilson, in a 1966 interview).

And then there was his education. At school he did piano and harmony lessons, and apparently showed a knack for arranging. But when asked to write a piano sonata he turned in a song called "Surfin'", and that was the end of his academic musical education.

Another handicap – or perhaps a blessing in disguise – was his damaged and deaf right ear. Without it, Brian could not, cannot, hear stereo. But some claim that this actually gave Brian a more concentrated type of hearing, enabling him to hear the important notes and chords without the confusion that the directional elements of sound can cause. It's akin to a device sometimes used by engineers and producers where they jam a finger into one ear in a bid to hear the fundamental tones of a piece of music. Well, that's the theory anyway. But none of this explains Brian's aptitude for recording. The family had had a simple mono tape machine, which he had learned to sing along with.

When he went into the studio, he did the same thing. On one of his very first real recordings early in 1963, "Surfin' USA", Brian experimented with doubling his own vocal. It was an effect that was to be everpresent on their records.

"It strengthens the sound," said Brian to an early interviewer. "Sing it once, then sing it again over that so that both sounds are perfectly synchronised. This makes it much brighter and gives it a rather shrill and magical sound without using echo chambers. It makes it sound spectacular, so much power."

The main thing that Brian brought to the studio, though, was a new perfectionism. "Brian was the first guy to do it until it was right," said Nik Venet. "He would hang in there for nine hours no matter what the cost. I used to think he was crazy, but he was right." The method itself was simple. The studio Brian chose for his escape from the Capitol tower in 1963, Western Recorders in Sunset Boulevard, was a 3-track set-up with an excellent natural-sounding echo chamber.

First the instrumental backing would be recorded, all together on the one track. "I don't know how to tell Dennis that the drumming on 'Little Deuce Coupe' isn't his," Brian agonised, in one of the first sessions where he brought in outside musicians. In fact, Carl and Brian himself were usually the only Beach Boys to feature instrumentally on their own records.

Once the backing tracks were down, the first set of vocals would be done, with Carl, Dennis and Al round one mike, Brian singing lead on another, and Mike on a third. Then they'd add another set of vocals, plus any extra sweetening they might need, for instance a harp or some extra percussion.

An essential part of Brian's learning process was the a cappella numbers like "A Young Man is Gone" from "Little Deuce Coupe" or "The Lord's Prayer". While the way the vocal lines shift against each other chromatically is not to everybody's taste, they did give Brian the chance to work with up to 10 melodic lines at a time. The experience is reflected in his first work with strings and large instrumental groups.

Once Brian had crossed the psychological hurdle of bringing in session musicians, he took full advantage of the available talent, using a team borrowed largely from Phil Spector's sessions. Drummer Hal Blaine is the most obvious presence, but it would be wrong to underrate the contributions of horn man Steve Douglas, bassist Carol Kaye, pianist Leon Russell and the rest.

It's difficult to imagine the sort of pressures the young Brian Wilson was under. Between September 1963 and December 1964, Brian produced four studio albums and a live album for Capitol. There was also the Christmas Album, where he sang most of the leads. And then there was the constant touring. It was all too much. On 23 December 1964, Brian had been married for just over a fortnight when he was sent back out on tour. He never made it, suffering a complete emotional collapse on the plane and being sent home.

He stayed at home from now on, but was determined to make up for his "letting down" the other guys by producing even more sophisticated backing tracks for when they came home. He picked up a taste for orchestral sounds when he did the Christmas Album with arranger Dick Reynolds, and this was to be reflected in "Today".

"The Beach Boys Today" (1965) is the turning point between the early and middle periods of Brian Wilson's production career. Side one contained a series of massively-produced rockers, enlivened by harpsichords and bursts of virtuoso percussion, with latin-inflected guitar chords well to the fore. But it is side two which marked the real advance, and the beginning of the type of production devices that were to characterise Brian Wilson's finest work: the skilful manipulation of echo rates, with smooth, churchy reverberation on the vocals, and harsh slapback tape and plate echo for drums, guitars and basses; prominent percussion, especially wood-block; instrumental doubling of solo vocal lines, and abrupt changes from solo voice to a cappella to orchestrated chorale; and rich bass sounds underpinning the arrangement and frequently leading the way through complicated harmonic progressions. We never forget that Brian was himself a bass player.

And so the early period ended. The middle period was less obviously fruitful, to begin with. Two "quickie" albums followed, "Summer Days (And Summer Nights)" which followed the pattern of "Today" but less convincingly, and "Party!", a fake-live album actually recorded in a studio. Brian's next important work was the single "The Little Girl I Once Knew", an experimental song full of tempo changes and dead stops. "Barbara Ann", a retrogressive piece of nonsense, knocked it off the chart and broke the gentle pattern of his explorations. Brian had, of course, been listening to what everybody else was doing. He stayed true to Spector, and would listen closely to the same small section of particular records over and over to work out what Phil was doing, and took the chance to sit around in his sessions and see how he worked.

When the Beatles broke big just as the Beach Boys came to fame, Brian was a little unnerved, but he hit back in the only way he knew, by making his records better. When "Rubber Soul" appeared in 1965, it represented the greatest challenge he had ever had. "A whole album with all good stuff," he would say to anyone he came across.

Brian's response was "Pet Sounds" (1966), probably the greatest single album in the history of pop music, possessing as it does an almost perfect unity of tone and arrangement.

Next month: "Pet Sounds" to date.