Thrash metal is the point at which heavy metal stopped being about power and started being about velocity. Everything else follows from that one substitution. The riff becomes a machined, palm muted line hammered out on downstrokes instead of a slow bending blues figure; the drummer takes his beat from hardcore punk rather than from rock; the singer stops trying to be beautiful; the songs stop being about mythology and start being about the news. It happened in a handful of garages between 1981 and 1983, it was fully formed by 1986, and it has been imitated continuously for forty years by people who mostly get the speed right and the rest of it wrong.
This is what the thing actually consists of: where it came from, what its mechanics are, which records define it, where its borders run, and how to tell whether a band you are listening to is thrash or merely fast.
A definition that holds
Thrash metal is fast, riff driven heavy metal built on palm muted downpicked rhythm guitar, hardcore derived drumming, shouted rather than sung vocals, and songs constructed as sequences of distinct riffs rather than around a chorus. It emerged in the United States and West Germany between 1981 and 1983 and reached its finished form in 1986.
Every clause in that sentence is doing work. Fast alone is not thrash, or speed metal would be thrash and it is not. Riff driven alone is not thrash, or Black Sabbath would qualify. It is the combination, and specifically the combination of a hardcore rhythm section with a heavy metal guitar vocabulary, that produced something neither parent could have made alone.
The three parents
Thrash has an unusually well documented parentage, and all three of its ancestors were active at the same moment at the end of the 1970s.
Motorhead came first and mattered most, because they demonstrated that a band could play at punk tempo with metal equipment and metal volume and be rejected by neither audience. Overkill in 1979 and Ace Of Spades in 1980 are the proof of concept for the entire genre, and Lemmy Kilmister's refusal to be classified is the reason the two scenes were ever willing to stand in the same room.
The New Wave of British Heavy Metal supplied the guitars. Iron Maiden and Judas Priest gave the harmonised twin lead and the galloping rhythm; Diamond Head supplied the riff writing, and specifically Am I Evil? and the 1980 album Lightning To The Nations, which Metallica have spent forty years openly acknowledging as a template; Venom supplied the attitude, the imagery and, with Black Metal in 1982, the name of a different genre entirely.
Hardcore punk supplied the engine. Discharge, from Stoke on Trent, built Hear Nothing See Nothing Say Nothing in 1982 out of a drum pattern so distinctive it acquired their name, and Black Flag and Bad Brains in the United States were already playing faster than anybody thought a rock band could. What thrash took from them was not the politics or the haircuts. It was the beat, and the idea that a song could be over in ninety seconds if it had run out of things to say.
The riff is the subject of the song
Start with the right hand, because everything else follows from it. Thrash rhythm guitar is downpicked: every note struck on the downstroke at tempos where alternate picking would be easier and would sound wrong. The downstroke gives each note the same attack and the same fractional silence in front of it, so a run of eighth notes arrives as a row of separate blows rather than a smear. Add palm muting, the heel of the picking hand parked on the strings just ahead of the bridge, and you have the chug: pitched, percussive, and tight enough for a drummer to bolt himself to.
Hold that for four minutes without letting the wrist relax into a shuffle and it stops being a technique and becomes manual labour performed to a tolerance. That is what James Hetfield does on Battery and what Gary Holt does on most of Bonded By Blood, and it is the single most imitated and least successfully reproduced thing in the genre.
The material on top is largely chromatic. A thrash riff sits on a low open string and walks upward by half steps, or hammers a pedal note while a second voice climbs a semitone at a time above it. There is very little blues in any of it and almost no pentatonic swagger, which is precisely what separates it from the heavy metal it grew out of. And because the riff is not a chord progression, the song cannot be about its chorus. Bands wrote five and six distinct riffs per song and arranged them like paragraphs, each earning its place and handing over to the next.
The beat underneath
The engine is the skank beat, taken whole from hardcore: kick on the downbeat, snare on the upbeat, hi-hat keeping eighths, driven until the snare is landing several times a second. It is simple to write and exhausting to play, which is why it sounds like effort even at low volume, and it is the clearest single marker that separates thrash from every kind of metal that came before it.
The double kick is the other half, and how a drummer uses it dates a record almost to the year. The first generation used it as punctuation: a burst of six or eight notes to shove a section forward or fill a bar under a riff change, and then off it. Dave Lombardo in Slayer was the man who made it continuous, laying it down as a floor and playing the rest of the kit on top, and every extreme genre that came afterwards took his answer rather than anybody else's.
The voice, and what it is not
Thrash vocals are barked. Not sung, not growled, barked: pitched speech delivered at the top of the chest with the hard consonants pushed forward, phrased rhythmically so that it doubles the riff instead of floating above it. Tom Araya, Paul Baloff, Chuck Billy and Mille Petrozza are doing four different versions of the same job.
This is the fastest way to tell thrash from death metal, and it is worth being precise about it, because the two get confused constantly. A death metal growl is produced with the false vocal folds and is deliberately unpitched and unintelligible; the words are texture. A thrash bark is pitched and intelligible; the words are the point. A band whose singer you cannot understand is not playing thrash, whatever the guitars are doing.
A band whose singer you cannot understand is not playing thrash, whatever the guitars are doing.
What the songs are about
The lyrics are the least discussed and most reliable marker of all. Thrash writes about the world outside the window: nuclear war, addiction, institutional corruption, television, prisons, mental illness, the news. It is a journalistic instinct. Where earlier metal reached for dragons and wizards and where black metal would later reach for the supernatural, thrash reached for the newspaper, and it did so at exactly the moment the Cold War was at its most frightening.
Slayer are the great exception and prove the rule by being the exception everybody notices: atrocity, damnation and death handled flatly, as testimony rather than protest. Anthrax went the other way into comics, Stephen King and, on Among The Living in 1987, a kind of energetic moral seriousness nobody else attempted.
The four scenes
Thrash was never one place. It arrived in four, roughly simultaneously, and each made its own dialect.
| Scene | Core bands | What it does differently |
|---|---|---|
| Bay Area | Metallica, Exodus, Testament, Death Angel, Vio-lence, Forbidden | Harmonised twin leads, half time drops, precision, dry production |
| Los Angeles | Slayer, Megadeth, Dark Angel, Hirax | Faster, atonal leads, no relief, continuous double kick |
| East Coast | Anthrax, Overkill, Nuclear Assault, S.O.D. | Bounce and swing, hardcore crossover, melodic singing |
| Teutonic | Kreator, Sodom, Destruction, Tankard | Lower and dirtier rasp, murkier production, a wall not a diagram |
| Brazil and beyond | Sepultura, Sarcofago, Voivod, Razor, Onslaught | Rawer, closer to death metal, made with almost no equipment |
The records that define it
Ten albums will teach anybody the genre faster than any amount of description, and eight of them come from a single five year window.
| Year | Band | Album | Why it is here |
|---|---|---|---|
| 1983 | Metallica | Kill 'Em All | The first thrash album, and the template |
| 1983 | Slayer | Show No Mercy | The other founding record, made in the other city |
| 1985 | Exodus | Bonded By Blood | The riff writing in its purest state |
| 1986 | Metallica | Master Of Puppets | The genre's arrangements taken as far as they go |
| 1986 | Slayer | Reign In Blood | Twenty nine minutes, and the end of the speed argument |
| 1986 | Megadeth | Peace Sells... But Who's Buying? | Technical writing and a political tongue |
| 1986 | Kreator | Pleasure To Kill | The German dialect, fully formed |
| 1987 | Anthrax | Among The Living | The East Coast, with an actual singer |
| 1989 | Sepultura | Beneath The Remains | Brazil, and the last great record of the first era |
| 2017 | Power Trip | Nightmare Logic | Proof the form still works when it is meant |
Where the borders run
Four boundaries cause almost all the arguments, and three of them are settled more easily than people pretend.
Speed metal is the closest neighbour and the hardest call, because the difference is attitude rather than tempo. Speed metal keeps heavy metal's melodic singing and its choruses and simply plays faster. Thrash throws the singing away.
Death metal takes thrash's speed, removes the pitched vocal, detunes further, replaces the chromatic walk with tritones and diminished intervals, and makes the double kick permanent. The bridge between the two was built in the Bay Area, by Possessed, whose 1984 demo was literally titled Death Metal.
Black metal shares Venom as an ancestor and almost nothing else. It wants atmosphere and cold; thrash wants clarity and impact. Tremolo picking replaces palm muting, and the production choice inverts: black metal hides its details deliberately, thrash exposes every one.
Groove metal is what several thrash bands became after 1990: the half time drop kept, the speed thrown away. Machine Head, late Sepultura and Pantera's neighbours all live there.
The arc, 1981 to now
The chronology is short and unusually clean. Formation between 1981 and 1983; the first albums in 1983; consolidation and the discovery of the local dialects from 1984 to 1985; the peak in 1986, a year that produced Master Of Puppets, Reign In Blood, Peace Sells, Darkness Descends and Pleasure To Kill between January and December; the commercial high water mark from 1988 to 1991, when the bands filled arenas and the records charted; and then a collapse between 1991 and 1993 that was less about grunge than about an industry deciding, all at once, that the shopping list had changed.
What followed was fifteen quiet years and then a revival that has now lasted longer than the original era did. Municipal Waste, Warbringer, Havok, Evile, Toxic Holocaust and, best of all, Power Trip rebuilt the form deliberately in the 2000s and 2010s, and the surviving originals came back alongside them. Exodus, Testament, Death Angel, Kreator, Sodom, Destruction and Overkill are all still making records, several of them better ones than they made in 1990.
How to tell, in thirty seconds
Put a record on and ask four questions. Is the rhythm guitar palm muted and picked downward, so that the notes arrive as separate blows? Is the snare landing on the upbeat several times a second? Can you understand the words? Is the song moving between distinct riffs rather than returning to a chorus? Four yesses and it is thrash. Three and it is probably speed metal or crossover. Lose the intelligible vocal and you have crossed into death metal, and lose the palm muting for tremolo picking and you are in black metal.
That is the whole apparatus. It was assembled by teenagers with no money in about thirty months, it has outlived nearly everything that was fashionable while it was being built, and the rest of it, from the first riff to the last reunion, is the thrash metal story. The parts that are stranger, funnier and more disgraceful than any of the above are collected in Thrash Metal Trivia, Records and the Trouble It Caused.
What it is not
Half the confusion about this genre is people applying the word to things it does not cover, so the exclusions are worth stating as plainly as the definition.
It is not simply fast heavy metal. Judas Priest's "Painkiller" is faster than a good deal of thrash and is a heavy metal song, because the drumming is rock drumming and the structure is built around a chorus. Speed on its own settles nothing.
It is not aggression. Hardcore is aggressive and is not thrash; the guitars are open and strummed rather than palm muted and downpicked, and the songs are statements rather than arguments.
And it is not a subject matter. A band writing about war and damnation is not thereby thrash, and a substantial number of thrash records are about the arms trade, addiction and the courts rather than about anything the sleeves suggest.
How to hear each element
Four short exercises, each about a minute, and between them they make the definition audible rather than theoretical.
For the right hand, play any riff from Master of Puppets and listen for the fractional silence in front of every note. That gap is the downstroke, and it is what makes a fast riff legible rather than a smear.
For the drums, follow the snare on anything from Reign in Blood. It is landing on the offbeat, twice as often as a rock backbeat, and that flatness is why the music feels relentless rather than merely quick.
For the arrangement, count how many distinct riffs appear in one song. A rock song has two or three; a thrash song has six or more, and it does not return to the first one at the end.
And for the vocal, notice that it lands with the guitars rather than floating above them. Turn the record down and the voice disappears with everything else, which is the opposite of how a hardcore record is mixed.
Why the definition matters
Not for the sake of policing a shelf. It matters because the four elements explain each other, and a listener who knows them hears considerably more in the records.
The drum pattern forces the guitar technique. The guitar technique limits how long a song can be. The song length forces the riff sequence structure. And the tempo makes a sung melody impossible, which produces the vocal. Pull any one out and the others start to fall over, which is why the genre has been so stable for forty years and why bands who take three of the four end up sounding like something else.
