Years of Production1968 – 1970
Number of Units52
Original Price£871
Dimensions W x H x D107 x 92 x 67 cm
Weight113.4 kg

The M300 was created in order to reduce the Mark II‘s size and weight. It was the first Mellotron not to have built-in speakers. However, an amplifier unit, the LSA 300, was available as an option.

The M300 features a solid-state preamp and Hammond spring reverb, applicable to lead instrument sounds only or to the entire keyboard.
The motor servo cards are CMC-4.

The M300 uses the Mark II multi-soundbank system but with a single 52-note keyboard.
The keyboard is divided in 4 parts: 3 keys for diminished chords, an octave for accompaniments, 3 keys for rhythms, and the other keys for lead instrument.

The M300 is the only Mellotron to use 1/4″ tapes with 2 tracks. A selector allowed the player to chose the A or B track, but not the two tracks at once. There is a total of 6 banks of accompaniment sounds and 6 banks of lead instrument sounds.

The first models (s/n 01 to 25) have the following controls:

  • Rhythm Volume
  • Pitch Control
  • Reverberation
  • Lead Volume

From serial number 26, the pitch control is removed to be available as an option.
A tone control for the rhythms and leads sections is added.
The layout is as follows:

  • Rhythm Tone
  • Rhythm Volume
  • Reverberation
  • Lead Volume
  • Lead Tone

[Click on the picture to zoom]

Brand new recordings had been made for this model. A first set of sounds (M300A) has been released in 1967, and was replaced by a second set (M300B) in 1969. The strings sound of M300A set is made of two violins playing in unison. This sound has been used by Gentle Giant and Barclay James Harvest.
The strings sound of M300B set is a solo violin, that you can hear on The Moody Blues’ Watching And Waiting from the album To Our Childrens’ Childrens’ Children (1969).

The M300 has been essentially used by Barclay James Harvest (on their first albums), Earth and Fire (Song of the Marching Children, Atlantis) and Gentle Giant (Gentle Giant, Acquiring The Taste, Three Friends). Aphrodite’s Child also used it on their first album (End Of The World), which included the hit single Rain And Tears.
(Audio excerpts in Audio section)

The M300 had a bad reputation because of its reliability problems. These were due to a poor lubrication of the tape guides, resulting in static electricity problems and tapes breaking during bank changes.
Now, these problems are solved after a full restoration by Streetly Electronics.


M300 #3-003

Photos: David Cilia – 2005
My M300 – It was sold to the Musée de la Cité de la Musique [See photos taken by the museum]

M300 #3-005

Photos: John Beresford – 2002
John Beresford’s M300



M300 Service Manual
M300 Service Manual


A first set of sounds has been released in 1967 (M300A), and was replaced by a second set in 1969 (M300B).

M300A – 1967

1A. Samba
B. Bossa Nova
1A. Flute
B. Trombone
B. Dixieland
B. Vibes
3A. Quickstep
B. Medium Foxtrot
3A. Clarinet
4A. Latin
B. Slow Foxtrot
4A. Spanish Guitar
B. Organ
5A. Slow Waltz
B. Viennese Waltz
5A. Organ
B. Celeste
6A. Cello
6A. Violins
B. Harpsichord

PIANO and ORGAN sounds can be played on the 52 notes of the keyboard:

  • for PIANO: 2A Station on the left with 2A Station on the right
  • for ORGAN: 6B Station on the left with 3B Station on the right

M300B – 1969

1A. Viennese Waltz
B. Quickstep
1A. Saxophone
B. Flute
2A. Samba
B. Slow Waltz
2A. Vibes
B. Clarinet
3A. 6/8 Tempo
B. Dixieland
3A. Trombone
B. Solo Violin
4A. Pop
B. Pop
4A. Harpsichord
B. Spanish Guitar
5A. Latin American
B. Slow Foxtrot
5A. Hammond Organ
B. Vibr. Organ

PIANO and ORGAN sounds can be played on the 52 notes of the keyboard:

  • for PIANO: 6A Station on the left with 6A Station on the right
  • for ORGAN: 6B Station on the left with 6B Station on the right