Guillaume studied Jazz double bass in Nice Conservatoire(FR) and continued in Amsterdam Conservatorium where he graduated. He had the opportunity to attend masterclasses with Kurt Rozenwinkel,  Brad Meldhau, Wynton Marsalis, Larry Grenadier, John Patitucci, Brian Blade, Ari Hoenig, Peter Erskine and more.

From 2005 to 2006 he has been performing and hosting 2 jazz concerts on a weekly base at l'Authentic restaurant Nice(FR). From 2007 until 2009 he hosted and performed 2 jazz concerts per week at Proef Amsterdam(NL). From 2009 till nowadays Guillaume is hosting and performing live music in Gollem's Proeflokaal in Amsterdam(NL) every Saturday where he plays with great musicians from the Netherlands.

in 2009 Guillaume was selected to the semi final of the “Keep an eye” jazz award with his own compositions and his own project. In the following he recorded 3 of his compositions.

Between 2007 and 2018  he has been playing as a free lancer or as an active band member musician in several projects performing and touring in France, Belgium and the Netherlands. Band member ship with: Wouter Penris band, Amsterdam Quartet, Purple Gazelle, Wet Dogs Trio, Medine Bouma Trio. Free lancer collaboration with: Benjamin Herman, Jerome Hol, Tineke Postma, Tim Welvaars, Erik Kooger, Jose Lopretti , Daniel de Moraes,  Thijs Kuppen, Klaas van Donkersgoed, Christian Pabst,  David Golek, Steve Altenberg, Baas van Lier, Berend van den Berg, Joost Kesselaar...

 Currently: he is working on his first album, producing music in his home studio,  and  is an active band member with 3 bands: 

.The WetDogs Trio: Daniel de Moraes on guitar and Erik Kooger on Drums 

.Purple Gazelle, a tap dance - jazz project with Marije Nie tap-dancing and a jazz trio with Erik Kooger and Christian Pabst. The project plays some of the best repertoire of Duke Ellington with an adding of our wild and delicate improvisations.

. Medine Bouma Trio: with Juan Rodrigo Santolalla Galan on the guitar. They play a selection of the best hits of Jazz, Soul & Pop  in an acoustic setting.

. Every saturday @ Gollem's Proeflokaal (Amsterdam) live music followed by  the jam session


Festival performances:

. UITmarket festival Amsterdam 2008: G.Ortet Band with own composition

. UITmarket festival Amsterdam 2009: G.Ortet & Franz von Chossy Duo

. Meer jazz festival Almeer 2009: G. Ortet band with own compositions.

. Bevrijdingsfestival Zwolle 2011: Sir Randall – Positieve Energie

. Red-light festival  Amsterdam 2014: Alex Rossi plays Jobim project

. Red-light festival  Amsterdam 2015: G.Ortet - Moraes - E.Kooger

. Meer Jazz festival Almeer 2016: with Olaf Keus Quintet


        He his currently teaching @:

. Leerorkest Amsterdam as a double-bass teacher for classical orchestra for children:

. Music for life Amsterdam:

. Private lessons at home