No instrument is more closely tied to progressive rock than the Mellotron, and almost everything interesting about it comes from the fact that it is not really a keyboard at all. It is a rack of tape machines with a keyboard bolted to the front: press a key and a strip of recorded tape is dragged across a playback head until you let go. It was built in a suburb of Birmingham, it was unreliable, it went out of production in 1986, and for about fifteen years it was the sound of ambition in British rock. Here is how it works, which models matter, and the records where you can hear it.

How it actually works

Each key on a Mellotron has its own length of magnetic tape underneath it – not a loop, a fixed strip of roughly seven to eight seconds. Pressing the key presses the tape against a capstan, which pulls it past a head; releasing the key lets a spring pull the tape back to the start. That single design decision explains most of the instrument’s behaviour. A note cannot be held indefinitely, because the tape runs out. Each note is a separate recording of a real player, so the tuning and timing wander slightly from key to key. And a pitch control that varies tape speed became the standard way of tuning the thing to the rest of the band, which is also why it drifts as the machine warms up.

Birmingham, not California

The design descends from the Chamberlin, an American instrument built by Harry Chamberlin. In 1962 Bill Fransen brought two Chamberlins to England and met the Bradley brothers of Bradmatic Ltd, in Streetly near Birmingham, who reworked the mechanism so that it could be built in quantity. The Mellotron was developed there in 1963. Bradmatic became Streetly Electronics in 1970; after a legal split over the name, instruments made from the later 1970s onwards were sold as the Novatron. Production stopped in 1986, with something in the order of 2,500 instruments built across the whole run.

The models that matter

The Mk I of 1963 was made in about ten examples. The Mk II of 1964 is the one that reached the studios: a heavy twin-manual cabinet with 35 sounds available on each manual, and roughly 160 built. The M300 of 1968 offered a single 52-note manual. Then came the M400 in 1970, which is the Mellotron most people picture – 35 notes, a single manual, and a tape frame that could be pulled out and swapped for another in a few minutes. Over 1,800 were made, and it is the reason the instrument travelled. Streetly returned with the M4000 in 2007, combining the M400’s layout with the bank selection of the earlier machines.

Three violins, flutes and brass

Each tape carries three parallel tracks, and a selector physically shifts the playback heads between them, which is why the standard frame holds three sounds. The famous one is the three-violin set, inherited from the Chamberlin: not a string section but three violinists recorded together, which is why it sounds like nothing an orchestra produces. Flutes and brass filled out the standard set. Almost every Mellotron part in the prog canon is one of those three.

The man who tested them

The first musician to build a career on the instrument had worked on the production line. Mike Pinder was a development engineer at the Streetly factory between 1962 and 1963, responsible for testing and quality control, and left in May 1964 to co-found The Moody Blues. He bought a second-hand machine and modified it, first using it on the 1967 single “Love and Beauty”, then across Days of Future Passed (1967), In Search of the Lost Chord, On the Threshold of a Dream, To Our Children’s Children’s Children, A Question of Balance, Every Good Boy Deserves Favour and Seventh Sojourn (1972). His engineering background was not incidental: a band whose defining sound came out of a machine that broke down needed someone who could open it.

King Crimson, and the machine that moved house

Ian McDonald played a Mk II on In the Court of the Crimson King (1969), on the title track, “Epitaph” and “Moonchild”. After McDonald left, Robert Fripp took over the instrument himself: the Mk II appears on In the Wake of Poseidon (1970), Lizard (1970) and Islands (1971), and an M400 on Starless and Bible Black and Red (both 1974), where it carries “Fallen Angel” and “Starless”. David Cross played one on Larks’ Tongues in Aspic (1973).

One Crimson Mellotron went on to a second career. In his sleeve notes Steve Hackett recalled that Genesis acquired a spare machine from King Crimson, and that the band had a nickname for it on account of how often it failed. That Mk II is the one behind the opening of “Watcher of the Skies” on Foxtrot (1972). Tony Banks has explained that he built the introduction from two particular chords because those were the ones that sat in tune on that instrument – a famous piece of prog writing shaped directly by the limits of the machine. Banks used a Mellotron across Nursery Cryme (1971), Selling England by the Pound (1973), The Lamb Lies Down on Broadway (1974), A Trick of the Tail and Wind & Wuthering (both 1976).

Yes, Pink Floyd and the rest

Rick Wakeman used an M400 with Yes on Fragile (1971), on “Roundabout” and “Heart of the Sunrise”, and on Close to the Edge (1972) across all three pieces. Patrick Moraz played one on “The Gates of Delirium” on Relayer (1974). Richard Wright had got there earlier than any of them, with a Mk II on A Saucerful of Secrets (1968) and on the title piece of Atom Heart Mother (1970). Edgar Froese took an M400 into Tangerine Dream’s Phaedra (1974) and Rubycon (1975). And there is a small oddity worth knowing: the Mellotron on “Tears”, on Rush’s 2112 (1976), was played by Hugh Syme – the designer responsible for the band’s artwork.

Why it stopped, and why it came back

Polyphonic synthesizers and then digital samplers did what the Mellotron did without the tape, the weight or the failures, and by the mid-1980s there was no commercial case for it. What brought it back was the opposite of what killed it: once every keyboard could reproduce a string section cleanly, the value of an instrument that could not became obvious. Software emulations and Streetly’s own M4000 have made the sound available to anyone; the machines themselves remain heavy, temperamental and expensive.

Where to start listening

For the sound at full stretch: In the Court of the Crimson King. For the most famous single entrance: “Watcher of the Skies” on Foxtrot. For the instrument as the whole texture of a record: Days of Future Passed. For the flutes rather than the strings: Selling England by the Pound.

Go deeper

The rest of the instruments are in the hub, the instruments of progressive rock, and the other keyboard that defined the era is covered in the Hammond organ in prog rock. For the players, see the best prog rock keyboardists. For the records, start with the best King Crimson albums and the best Genesis albums. The British scene that put this instrument at the centre of its sound is the subject of Beyond the Thames, the second book in my Beyond the Sound series.

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