Robertsonics Mellotron Primer

The mellotron is a musical instrument that, for some at least, defines the sound of Progressive Rock from the late 1960's through the mid 1970's. Predating the advent of microprocessors and digital memory in electronic musical instruments, it was the first "sampling" instrument, allowing a keyboardist to play the sound of real acoustic instruments - in particular, violins, cellos and flutes.

The original intent was no doubt to exactly recreate the sound of these instruments, but the end result was a sound that was completely original, instantly recognizable and to my young ears, unearthly.

While probably more widely heard on a few popular recordings by the Beatles (the flutes in Strawberry Fields), Led Zeppelin (the violins in Kashmir), and Elton John (Daniel) the Mellotron was a mainstay of such Prog Rock pioneers as King Crimson, Yes, Genesis and Strawbs, to name a few.

More than anyone else, however, it was the Moody Blues who used the "tron" to best advantage. I recall vividly being enchanted first with the mysterious and haunting orchestral music of "Tuesday Afternoon" and then by the realization that these sounds were coming from a keyboard instrument played by a single person.

As my musical tastes matured (my opinion of course), I discovered Yes, and was drawn to the grand, orchestral (and rather long) arrangements. For those with the patience, their 1974 double-album release "Tales of Topographic Oceans" contains an incredible variety of Mellotron sounds, so tastefully woven into the fabric of the music that it takes a close listen to pick out the instrument. Unlike some bands, Yes used the Mellotron to enhance the scope and power of the music without drawing attention to the "gimmick".

Particularly with Yes, the resulting sound is completely unique and instantly recognizable as a Mellotron. If the same parts were played using real versions of the same instruments, a violin section for example, the music would have a different feel. In this way, the Mellotron is not simply a cheap replacement for and orchestra or choir, but a valid instrument in its own right.

There were several models made, but the most numerous and widely used was the M400, mainly because it was by far the most "portable', weighing in at a around 120 lbs. There were only about 1800 M400s made between 1971 and 1986, and many of them have succumbed to the wrath of frustrated musicians - most notable one or two that were reportedly set on fire by Rick Wakeman.

how it works

This is clearly a case where a picture is worth a thousand (or more) words. Click here for a really cool interactive demonstration of the inner workings of a Mellotron, courtesy of the Audio Playground Keyboard Museum.

The Mellotron M400 has 35 keys, spanning 3 octaves. Associated with each key is a length of 3/8" magnetic audio tape recorded with 3 parallel tracks. For the moment, assume that there is only one track on each tape, and the sound to be played is "flute". Each tape has an 8-second recording of an actual flute playing the note corresponding to the key to which that tape belongs. Middle C has a tape recorded with the sound of a musician playing middle C for 8 seconds on a flute. This is not a tape loop - playback always begins at the start of the tape when the key is pressed - so the recording has a natural evolution for that instrument.

There is a single motor driving a long capstan (rod) that extends underneath all 35 keys. When a key is pressed, a pinch roller pushes the corresponding tape against the capstan causing the tape to begin traveling over a playback head. There are, of course, 35 playback heads. The tape starts out on a removable tape frame which applies tension via a spring return mechanism. As the capstan pulls the tape over the playback head, it drops into a collection bin where it simply folds up on itself. When the key is released, the pinch roller releases and the spring mechanism quickly pulls the tape back to its original position, ready to be played again.

Now add to this that each tape actually has 3 tracks, with a rather crude lever mechanism that shifts the playback heads left or right to pick up one of the three parallel tracks. In addition, there is a pitch knob which adjusts the speed of the capstan motor, allowing those weird, impossible, orchestral slides that Mike Pindar of the Moody Blues was so famous for (think "Timothy Leary: Legend of a Mind")