The Microtonal Trumpet

Stephen Altoft and Donald Bousted perform at Art’s Birthday, Freiburg, 2020

A FREE pdf book (covering a full description of the microtonal valve mechanisms) and a number of free resources (including fingering charts in 19-, 24- and 48-div) are available on request, hosted on Dropbox (fill out the contact form below).

Microtonal trumpets date back to the early twentieth century and there are surviving examples in the museums in Odessa and Prague.

The Microtonal Trumpet Project, which began in 1998, is a systemically researched and documented project between Donald Bousted, composer and Stephen Altoft, trumpeter.

Since 1998, the project has expanded exponentially both in the development of ideas, modified instruments and in the creation of new music.

You Tube Playlist

Listen on Bandcamp

Stephen and Donald have presented the project at:

The University of Surrey, The Royal Academy of Music, Trinity College of Music, York University, The University of Bristol, Brunel University, The University of Huddersfield, The University of Leeds, Keele University, The University of Aberdeen, UK MicroFest’s 1-4 (all UK), Staatliche Hochschule für Musik, Freiburg, (Germany), Fondation Royaumont (France), Hochschule für Kunst Bern (Switzerland), Kunsthochschule für Medien, Cologne (Germany), Hochschule für Musik und Theater, Hamburg (Germany) EUROMicroFest 2013 and Napier University, Scotland, Staatliche Hochschule für Musik und Darstellende Kunst Mannheim (Germany), Art’s Birthday 2020 (South West German Radio), E-Werk, Freiburg (Germany)

The Microtonal Trumpet, to date, has been concerned with playing quarter-tones (24-div) and eighth-tones (48-div) on a standard 3-valve trumpet and, using a specially constructed conversion kit, quarter-tone and 19 equal divisions of the octave (19-div).


19-div valve designed for Stephen’s Bb concert trumpet

The project, as documented, is based around 24 microtonal studies by Donald Bousted.  See the publications page for details.

The Yasser Collection CD

In order to explore the 19-div tuning on the trumpet, Stephen commissioned 19 solo pieces from 17 international composers. The resulting CD, called “The Yasser Collection” can be heard on Bandcamp and is also part of our Dropbox resources. 


Stephen presents 11 recently written pieces in 19-division tuning.  Like the Yasser Collection before it, these pieces are diverse in orientation and international in outlook. The Liner notes are here: RASP CD Programme Notes. Order the CD from our Publications page or buy on Bandcamp.

Review from theWholeNote:
“Stephen Altoft is an explorer who draws maps of musical terrain with his trumpet. The title track, his own composition Rasp, is a slow motion expansion from a breathy hiss to an intense broken buzz. The logic of the progression is as stark as the material itself: a fearless opening statement … announcing to the listener “this is what I work with. The following tracks (especially the tenth, Studie by Manfred Stahnke) demonstrate the microtonal potential of Altoft’s remarkable customized trumpet. An extra valve and tubing permit him to divide the scale into 19 pitches without the guesswork of constantly adjusting a tuning slide mid-phrase. The effect is both comforting and disconcerting: one hears unusual pitches securely nailed instead of groped for. And that’s the point, I believe – to re-normalize the various tunings that equal temperament has hidden behind its bland reductiveness.” Max Christie

Time Dreaming Album (Digital Platforms only)

The third solo 19-div trumpet album contains 12 pieces in 19-division tuning, many of which address harmony much more closely. This album features the debut recording of the 19-div flugelhorn.
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Available on most digital platforms (Spotify, Apple Music, Amazon Music etc etc).

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