Are these the 10 heaviest albums ever made?

There's a certain part of metal that gives it its edge; an extra bite that separates it from pop. It can mean enormous riffs, ungodly speed, wrecking-ball grooves, anything that makes music hard, loud and exciting. To celebrate the return of Machine Head to the cover of Kerrang! this week, the editors decided to count down the 50 heaviest albums ever made. The point being this: we wanted to celebrate how varied and far-reaching a term "heavy" can be. Is it the point at which, for some, music stops being music, or is it the entry point to a whole world of new, 'eavy sounds?

To give you an idea of what we've put in the list, here are 10 examples of what we're talking about.

MACHINE HEAD – BURN MY EYES
What Oakland, California's Machine Head did for metal with their 1994 debut Burn My Eyes was simple: they gave it back its street-level grit and fiery attitude. It gathered together the last decade-and-a-bit of heavy music – hardcore, thrash, death metal – to create a sound that had the gut punch of Metallica and Slayer, the brawling energy of hardcore bands such as Agnostic Front and Cro-Mags, with a razor-sharp edge that brought metal bang up to date.

THE BEATLES – WHITE ALBUM
Consider this: in 1968 the White Album was perhaps the most off-the-wall, extreme and challenging record available to a mainstream audience. By the time they came to record it, the Beatles had more money than they could ever spend, and so could afford the state-of-the-art studio gear to make whatever noise came into their heads. Some of it is just weird sounds (Revolution 9), but in Helter Skelter – a song that would inspire Charles Manson to order his "family" to commit their atrocities – they took how heavy a guitar could sound to new peaks of weightiness, with a fuzzy tone that is still heavier than most metal bands.

SLEEP – JERUSALEM/DOPESMOKER
The legend goes like this: Sleep got signed to a major label in 1995, having made a name for themselves in the underground. The major label gave the three California stoners a pile of money, which they apparently spent on weed, before handing in an hour-long hymn to doob.

The label dropped them and shelved the album. It was later released on indie labels Rise Above (the shorter Jerusalem) and Hydra Head (the full, glorious riff-fest that is Dopesmoker).

ELECTRIC WIZARD – DOPETHRONE
Electric Wizard's 2000 album Dopethrone is built of a heaviness that rumbles and shakes, squashes and suffocates. The work of three druggie burnouts from Dorset, it may have been conceived in a haze of hash smoke and LSD trips, but this is no hippy album. The drugs were part of a quest for oblivion, and the sprawling, aggressive sludge that lurched through songs such as We Hate You and Funeralopolis was forged of a complete hatred for everything and everyone.

DISCHARGE – HEAR NOTHING SEE NOTHING SAY NOTHING
Discharge once said in an interview that they make "noise, not music". Not a bad approximation from the Stoke-on-Trent punks, given that 1982's Hear Nothing … sounds like the third world war being forced through a stack of knackered, over-driven amps. Boiling over with the frustration of the youth of Thatcher's Britain, it's a furious open wound of a record that screamed so loudly that, all the way across the pond in California, four spotty teenagers calling themselves Metallica fell under its influence.

NAPALM DEATH – SCUM
If, to most normal people, Napalm Death's 1987 debut album seemed a little daft, they could have been forgiven for thinking so: the tempo was so fast drummer Mickey Harris had come up with a new style of playing to keep up, you couldn't really hear any of the grunted, politicised lyrics, there was a song that lasted less than one second (You Suffer), and there was a different lineup playing on each side of the record. But, by God, what furious anger the Brummie barnstormers cooked up.

MASTODON – LEVIATHAN
Like cavemen with guitars, there's something primal about Atlanta, Georgia prog-metallers Mastodon's heavy metal thunder. Already touted as ones to watch thanks to a reputation for all but shaking venues to the ground with their riffs, when Leviathan hit in 2004, it made even the closest competition sound tame. Not only that, but the incredible musicianship that makes up Leviathan's musical odyssey meant these four hairy, gnarly dudes were quickly touted as some of the finest players in metal, perfectly balancing immense brain with earth-shattering brawn to create an album that packs as much punch as it does grey matter.

SLIPKNOT – IOWA
By the time they came to make Iowa in 2000, Slipknot had become global metal stars. But the band had burned out from a punishing tour and, without a chance to take a break, the nine masked men from Iowa went almost straight into the studio. Things were already strained from more than a year on the road, and band members were seeking refuge in drugs and alcohol. The music that came out of this pressure cooker was a furious tangle of misanthropy, self-loathing, bitterness and barely-controlled fury.

Amazingly, it hit No 3 in the US albums chart.

CONVERGE – JANE DOE
However you define heavy, Jane Doe, the fourth album by Boston noiseniks Converge from 2001, fits the bill. An almost uncontrolled, scalding noise that tears through your speakers like a forest fire, it's a hardcore album that sounds like its been crudely hooked up to the mains just so its creators could make as many sparks as possible. But unlike so many albums from its genre, while it may be shockingly powerful throughout, the rollercoaster of different sounds Converge use is dizzying, disorienting and a complete white-knuckle ride from start to finish.

SLAYER – REIGN IN BLOOD
Our No 1, the heaviest album ever made. Why? Because when the LA thrashers released it in 1986 it was faster, harder and louder than everything that came before it, and nothing since has ever come along to truly trump it. There have been faster bands, there have been bands with fatter low-end sounds or more inhuman vocals, but nobody has ever been able to match Reign in Blood for what you get from all the elements mixed together.

Clocking in under half an hour, the band played so furiously that the finished product clocked in at seven full minutes shorter than the demo versions. That's fast, but not so fast you can't make out what Tom Araya's singing about: serial killers, the devil, and, most controversially, Nazi doctor Josef Mengele on Angel of Death. So controversial was the track – which doesn't condone or condemn the man's terrible actions, but the band always argued they didn't need to tell their fans what to think – that US distributors refused to touch the album. So the heaviest album ever – and one of the most controversial.

All hail Slayer!