Sunset Sound, Hollywood, between 29 August and 4 October 1977. In the live room stood a Marshall 1959 Super Lead built in 1967 or 1968, a hundred watts, plugged not into the wall but into a Variac, a variable transformer wound down to feed the amplifier somewhere under ninety volts instead of the hundred and twenty it was designed for. Warner Bros. was paying for the tape.
The twenty-two year old from Pasadena who starved his own amplifier of power on purpose, choking the voltage on its valves until the attack of every pick stroke sagged, thickened and came back to the microphone the colour of strong tea, was Eddie Van Halen, and the band's debut, released on 10 February 1978, put that sound on millions of turntables. He called it the brown sound. The heavy metal guitar tone has been argued over ever since, and most of the argument is about the wrong knob.
The knob people reach for is gain. The one that matters is the middle.
The heavy metal guitar tone lives in the midrange
Go back to the source. The Aston guitarist who plugged a Gibson SG through a modified Dallas Rangemaster treble booster into a Laney Supergroup, and then set the presence, the middle and the treble on ten and the bass on nothing at all, was Tony Iommi, and that is the configuration most accounts give for the early Black Sabbath records. No bass. The weight a listener hears on those records comes out of the middle of the spectrum, roughly the octaves between 250 hertz and 2 kilohertz, pushed so hard by the booster that the valves in the preamp break up and hold the note.
That is the first rule, attested on almost every record the style made between 1970 and 1985. Bass on a guitar is mud that the bass player has to wade through. Treble alone is a kettle whistle. The middle is where the pick meets the string and where the note has a body, and a heavy metal band with two guitars and a singer in the upper register needs that body more than any other kind of rock band, because the middle is the only room in the house the guitars can stand in without trampling somebody.
Gain is a gap between two stones
A miller grinding wheat sets the runner stone above the bedstone with a screw called the tentering gear, and the width of that gap is the whole trade. Set it wide and the grain drops through cracked but whole. Set it close and the stones bite each other, heat the meal until it scorches, and strike sparks off the quartz in the stone that can burn the mill down, so the miller works the screw by feel, a hair at a time, rubbing a pinch of meal between finger and thumb.
Gain is that gap. Too little and the power chord comes through as separate cracked notes, a clean amplifier being polite. Too much and the preamp grinds the notes into each other until every chord comes out as one hot grey powder of fizz, the fifth and the root smeared together and the palm-muted chug reduced to a hiss. The classic tone sits exactly where each note of the chord still arrives as its own grain, milled fine, and no finer.
Too much gain grinds the notes into each other until every chord comes out as one hot grey powder of fizz.
The records back that up. The guitars on the heavy metal albums of 1976 to 1984 carry far less distortion than players who learn them on a modern high gain amplifier expect, and the power in them comes from volume, from the output valves working hard in a loud room, and from the midrange push in front of the amplifier rather than from the preamp stacked into saturation.
The song that shows the brown sound at work, released on the debut and then as a single in 1978, is "Ain't Talkin' 'Bout Love", the riff picked through the chord one string at a time so that every note rings on its own, over a guitar built from a Stratocaster body and neck with a single rewound Gibson humbucker in the bridge, dipped in wax to stop it squealing. The Variac did the rest.
A pedal and an equaliser in front of a rented amp
The same logic travelled to England. The Californian guitarist who recorded Blizzard of Ozz there in 1980 through a rented Super Lead, his own white Marshall not yet delivered from the factory, was Randy Rhoads. He kept only a touch of overdrive on the amplifier and did most of his shaping on the floor, with an MXR Distortion+ that was almost never off and an MXR ten band graphic equaliser pushing a broad hump into the midrange around 500 hertz, a 1974 Les Paul Custom feeding cabinets loaded with Altec speakers.
The song that puts the whole method on film, shot on stage in 1981 with Ozzy Osbourne, is "Mr. Crowley": a keyboard introduction, a riff that stays articulate at full volume, and two solos where the midrange push lets each fast run of notes slice through the band like a hot wire through a block of polystyrene, instead of dissolving into the cymbals. The Distortion+ was a cheap pedal. What made it sing was where the equaliser put the weight.
Rhoads died in a plane crash in Florida on 19 March 1982, at the age of 25. Five years later Epic issued Tribute, a double album of live recordings made with him in 1981, and it remains the plainest document of that rig at full stage volume.
The formula was widely copied through the eighties, by common consent the default tone of the decade: a Marshall, a pedal or a modified preamp for more gain, and the middle kept high. The one real change was the amplifier doing more of the work itself once the master volume designs spread, which is a story that belongs with how the records were made.
The scoop, and why heavy metal kept its middle
Then thrash turned the equaliser upside down. Released by Elektra on 25 August 1988, with the guitars cut through a Mesa/Boogie Mark IIC+ and the graphic equaliser set in a V, lows and highs up and the middle sliders dragged to the floor, ...And Justice for All was the record that carved the midrange out of the metal guitar, and the San Francisco quartet that made it was Metallica. The bass guitar on it is famously hard to hear, a mixing choice the band's own producer and members have since confirmed.
A scooped tone is a hollow chocolate egg in a shop window, huge, glossy and wrapped in foil, and the moment the bass and the drums close their teeth on it there is nothing inside. On its own in a bedroom it sounds enormous. In a band it vanishes. That is why the heavy metal bands, with two guitars trading harmonies and a singer climbing above them, never went along with it, and why a thrash guitarist and a heavy metal guitarist can play the same amplifier and sound like different species.
The alloy that holds the style together is simple to write down and hard to play. Enough gain for the note to sustain, not enough to blur the chord, the middle high, the bass low, and the volume loud enough to put tensile strain on the output valves rather than faking it in the preamp. The hands finish it. Picking attack, a palm resting on the bridge and the guitar's own volume knob change the tone more than any pedal on the floor, and the players who got the sound were the ones who learned to ride that knob.
The pickup matters too, though less than the catalogues claim. A humbucker, two coils wired against each other to cancel the hum, hands the amplifier a thicker and hotter signal than a single coil, which is why the Les Paul, the SG and Van Halen's patched-together Stratocaster all carried one where the pick hits the strings, and why a stock Stratocaster sounds thin to a heavy metal ear.
What the guitar shares the room with
A guitar tone is never heard alone on a record. It has to fit around a kick drum and a snare, and the drum sounds of the eighties, gated, triggered and huge, pushed the guitars into a narrower band of the spectrum than the seventies had allowed them, which is part of why 80s metal drums sound that way.
The tone was never the whole story. It was the sound of the riff, and the riff came first, carried from a Birmingham rehearsal room through every decade the music has lived, which is set out in order in the index of the series. Turn the bass down. Push the middle. Leave some gain in the box.
