In hip hop, what's left out of the sound mix is often as important as what's kept in. Think of DJs and producers as they dig through crates of records in search of the perfect drum beat, the perfect horn stab, the perfect bassline: what's left out is a whole lot of extraneous music and vocals that are simply surplus to requirements.

Now let's look at the case of Joseph Saddler, a.k.a. Grandmaster Flash. To call him a legendary hip hop pioneer would be an understatement. He rocked the turntables at block parties in the mid-'70s South Bronx when no one knew what hip hop was, was about to be, or could be. He arguably invented the art he calls cuttin' records - otherwise known as scratching. Later on, in the early '80s, after hip hop was finally laid down on wax, he and his group of emcees, the Furious Five, were responsible for - or, at least, credited for (though that's another story) - The Message, hip hop's first slice of cinema verite street realism, and much, much more besides.

How do you tell Flash's story in 2009 journalese? The answer is that you don't, except by omission. David Ritz has already ghost-written Flash's autobiography, The Adventures of Grandmaster Flash: My Life, My Beats (Random House/Broadway). And Flash himself comes with a well-earned reputation for not suffering fools gladly. We have to walk on eggshells here or Flash will be monosyllabic. He might even walk right out on our interview, as is his prerogative.

Thus, the law of omission comes into play. No one, least of all Flash himself, mentions the words "Sugar Hill Records" - the label Flash was signed to in the early '80s and fought a lengthy legal battle to reclaim his name from. We don't talk about the Furious Five. Flash's former cocaine addiction and subsequent redemption doesn't get a mention. The thorny question of whether it was him - and it was him - or Grand Wizard Theodore that started the art of cuttin' records doesn't surface. Flash is happiest with the concept of the here and now. Apart from the book, he has a new LP, The Bridge: Concept Of a Culture to promote, and we hope, slightly deviously, that by shedding light on the present, he will come to acknowledge the past and future of hip hop he so obviously embodies.

There's no need to blow a gasket. Flash is cool. Late January in a central London hotel at an ungodly early hour of the morning (well, 10am), he's never less than forthcoming on any subject within the parameters that we've set. He's not averse to going over well-worn territory and he's never rude, even when he sometimes endearingly emphasises a point, as if speaking to a child: we are children of hip hop after all, we've grown up on and with hip hop. But Flash has grown up in hip hop, and this slight figure with his visible battle scars doesn't act like a grizzled veteran. As The Bridge evinces, Flash is still very much a man of the moment. Does he feel that hip hop respects its elders?

"I think that respect is given to an individual", he replies. "Me, I have no problem. We have, like, arms open all the time. I'm called Grandmaster. I'm called Pop, called Dad, called Flash. I don't really have any problem with respect. I also give respect."

The reason the question seems relevant is that the past and present of hip hop is littered with old time heroes. Whenever some new jack emcee comes on the scene - and Flash is emphatically a DJ and producer, never a rapper - they cast themselves with typical braggadocio as year zero and suggest that everything before them is null and void.

"With hip hop", he continues, "if you're gonna speak from a chronological sense, you must start at the beginning. You must include Afrika Bambaataa, you must add DJ Kool Herc, you must add Grandmaster Flash - or whatever it is you're doing from a chronological state becomes sort of phoney. So, I think we're embedded in stone. there. And, most importantly, I still tour. I don't wanna be a myth in people's minds. I don't wanna be folklore. You can see me performing in a club somewhere, and I will talk to you. I'll shake your hand. I'll give you a hug. So, you ain't gotta tell your people: 'Well, I've heard of Flash on the internet and I read some stuff'. You can say: 'No, I was in a club with him last night'. In order for me not to be folklore or a myth I think it's my duty to be present. And, as long as I can basically do this, I will do it."

The Bridge is Flash's first major full-length foray into the studio as a DJ and a producer since his final recordings for Elektra Records in 1987. In the interim he's lived a lot and kept his reputation as a DJ going, as his autobiography attests. And it's as if he has put all those life experiences and more into the mix, while remaining defiantly current, as well as never neglecting to rock a party. The LP seems conceptual in a way: was the concept that of a bridge between past and present?

"It's a bridge between different cultures", he replies. "It's a bridge between different places and cultures I've been blessed to see. I guess it also has to do with the past and now. You don't know what tomorrow brings. But this project was conceived from the mind of an international DJ. Some of the tracks are what I call pop-hop, some underground; some are party tracks, some of them have something to really tell you. Some have an R&B vibe, some have a club vibe, some have more of a street vibe, and some are just headbangers. Most importantly for me, for the vocalists I wanted to find talent that's not yet discovered and pair them with talent that was big. I wanted to pair up talent that didn't speak the American language with someone that did speak in English on one record. These type of things aren't commonly done in hip hop, so I've been blessed to see these things to fruition."

It's noticeable that there's a lack of overtly political sentiments on The Bridge. And while not referring back to The Message or any of the other Furious Five-helmed tracks that brought the politics of the street into the mainstream for the first time, was this a conscious decision on Flash's part - a sort of subliminal clean break from the past?

"Me, as a DJ, I don't do politics", Flash laughs. "There are people who are expert at that - rappers, people who are expert in that area. As opposed to me trying to do something to fake it, I'd rather just do what I do. When I'm in the club I'm not trying to be political. I'm trying to jam. Emcees and rappers that are really great at that, I let them do that. It's like Nas, we got KRS-One, we got Common, we got those. I'm not those people and those people are not me, OK? When I'm jamming, I'm not an expert at trying to be political in the club. I'm trying to get your body moving. I'm trying to temporarily take away your pains for a few hours while I'm there. Give you some joy. That's what I do."

As opposed to being in a DJ booth, does he enjoy being live onstage?

"I don't too much like DJ booths," he says. "I prefer DJ-ing on a live stage. That's where I'm most comfortable. All of us as human beings have a certain way of feeling comfortable. I'm most comfortable with performing on a stage. From my point of view, all my troubles go away. I feel sorta whole. You have those people who would shudder to be in front of thousands, performing. Me, that's like my living room. My comfort zone is performing in front of thousands and thousands of screaming people."

It's instructive when bridging Flash's past and present to also notice there's hardly any swearing on his new record. In the early days of recorded hip hop, this was a given. It was NWA that changed the game with Straight Outta Compton, when the language became more explicit and the N-word was no longer taboo in recorded hip hop. Flash says he didn't give the featured emcees, who include Q-Tip, Busta Rhymes, Snoop Dogg, Big Daddy Kane and KRS-One, amongst a host of others, any briefs, except on Bronx Bombers, where the three Bronx rappers were under orders to talk about their storied borough. But maybe out of respect for the time Flash emerged from, the emcees found other ways to express themselves. Asked his views on gangsta rap - and, by inference, explicit hip hop - he bristles at the labelling.

"Hmmmm," he simmers as he composes himself. "When I'm asked that question, I always tell the person to explain to me what gangsta rap is. Nobody gives me the right answer. Here's my problem with the whole labelling thing: This thing's called hip hop. When you think about all these other genres of music, whether it's R&B, rock, pop, or whatever, it's not something-pop or something-R&B or something-jazz, it's jazz, it's pop, it's R&B, it's funk, y'know? This is hip hop. And, in hip hop, what makes this so beautiful is that we can musically intertwine any type of different musics and come up with a whole 'nother formula and musically call it hip hop. We can lyrically also talk about anything and put it on top of this intertwined music and call it hip hop. Now, where the labels come in, I'd like to find out the person who did that. Because hip hop is just poetry to the beat of music. But it's also the intertwining of different musics to make a music.

"To this day I don't know what gangsta rap is and who does it," he continues. "I know plenty of people that talk edgy - let's call it edgy; and there are those that talk smooth; there are those that talk about their clothing; there are those that talk about women; there are those that talk about 'I'll beat you down'. There are those that talk and make you laugh. That's been going on since the '70s. Who decided to put a sticker on it? I'd like to meet that person and have a really serious conversation."

What Flash is really known for is transforming the craft of the DJ into a bona fide art. There's a minor interlude on The Bridge, Zuka the Sound, where he cuts up a simple tone and makes it literally sing in the digital realm. He's adamant that cuts are meant to be rhythmic and melodic, not distasteful. And he should know, as all those years ago, in 1981, he created the first record that really showcased the skills of the DJ in hip hop: The Adventures of Grandmaster Flash on the Wheels of Steel. It came out of the blue and still seems unearthly and unremittingly classic to this day.

"It came out of the blue for me, too", he agrees, "When I was in this record deal, this earlier record deal..." - notice he doesn't mention Sugar Hill Records by name - "...I had asked the people while we were making the regular vocal emcee records, I would say to the label owner, 'Is it possible that I could make a record using records?'. And they would look at me [makes quizzical face], like, 'What do you mean exactly?' And years passed and they had respected my reputation for what I did on the turntables, and finally said, 'Well, Flash, remember that time that you asked us for permission to do that record using records? Let's try that. Pick the records you wanna put on the disc.' So I picked the records and I made the song and we put it out.

"In America, it was like, 'Oh, this is different'. But what catapulted that record to the super-success that it was, was when we distributed it here in the UK. When it got here, for some reason... I'll never forget, when I was touring with the group that used to be with me..." - notice he doesn't mention the Furious Five by name - "...we were doing press and they kept asking us about The Adventures of.... We were on The Message, which was a big, big song, but journalists kept asking for and about The Adventures Of...; kept asking for that. And it got back to the record company and they said 'Something's going on in the UK.' People were understanding what I did with turntables. And that record kept getting plays, and I kept getting people walking up to me, saying 'thank you for making that record.' I'm like 'They... Got... It...!' The UK was the first country that really understood this DJ record. And then, from there, they brought in other countries. Finally, people understood the whole thing - that the DJ could be an artist in himself, as opposed to just the guy who plays the songs for the emcees. Now the artist alone became an artist. And you guys got it first. Figured it out. Quickly. Soon as you got it, you figured it out."

After all this time, all that water under all those bridges, and all that innovation, what gives Flash his philosophy? What's his way of seeing the world? How does he deal with people?

"Put it this way," he says, "I do lot's of reading on life. Life books, I call them - self-teach books. I read Deepak Chopra's books. They teach me to understand and see how people work. In that sometimes people may say and do and feel things about you, but you must allow them to be the person that they are. Even if it's something that's said to you that might appear to hurt you, it can only hurt you if you allow it in. So, it's a way of teaching me to deal with everyday life stresses. People are people. People will do things. What it comes down to is that the only person I'm responsible for is me. I cannot be responsible for what people say or do to me. I do a lot of meditation. I eat organically 65 to 70 per cent of the time, I do lots of praying, and that kinda keeps me on kilter."

Flash says the only way you can survive in hip hop - and, to extrapolate, in life itself - is that you have to respect change. And he should certainly know, having been through so many changes himself and still being here, still being grounded. He's a hip hop treasure, self-described but universally regarded as one of the architects of hip hop. The last words, obviously, must go to him.

"You have to be able to respect change, because change is gonna come regardless," he says. "It's something you cannot stop. Either you recognise change and you work with it or it works against you. For example, I played some things in the '70s that I've had to change just a little bit so I can still get what I do across to people. I couldn't do it exactly the same way. The only thing I could do exactly is play the same records. But I play new music. I love it. When I started it was new music then, so I play new music now. When I played Good Times or Apache, those were brand new records of that time. So now I play brand new records. If I played Good Times all the time, I have to play Nas, which is considered new. And I gotta play Jay-Z, which is considered new. And I gotta play Common, which is considered new. I have to do these things in order to expand my audience. There are certain records that you guys love that I must play, that maybe I can't play in America. Or vice-versa. But that's it: how I get my message to you is slightly different now. How I get it to an 18-year-old is maybe slightly different.

"So I take credit," he concludes. "But the most important thing is that they get it. Sometimes you have to change the fabric, so it goes to their brain. And I call that change. I think change is good. Change has allowed me to be here right now."