This paper deals with Qutb al-Din al-Shirazi (1236-1311)’s encyclopaedia Durrat al-taj li-ghurrat al-dabaj, more precisely with the chapter dedicated to music and known as the Dar ‘ilm-i musiqi. Though the article’s title supposes an analysis of al-Shirazi’s viewpoint on instruments, nothing is really said on this point till a footnote close to the end of the paper (162) informs us, that “Qutb al-Din al-Shirazi did not give detailed description of musical instruments. This gap may be filled by consulting other descriptions from that period.” Such a reserve does not prevent the author to provide several classifications supposedly borrowed from al-Shirazi’s text — which seems improbable, as Shirazi in his Dar ‘ilm-i musiqi deals mostly with the nature of sounds, and with issues of pitch and power. The article’ framework is disorganised, going from one subject to another and then coming back to another one, but still full of other authors’ theories, though we do not always understand who said what. The first aim of the author was to lead an historical comparison in order to evaluate changes in the use of musical instruments, from al-Farabi (867-950) to al-Shirazi, but it rather constitutes in series of non-related remarks and generalities. In conclusion, the author notes that “Qutb al-Din’s musical investigations were built on the work of earlier great thinkers” (163), which appears the least to say. In fact, as was recently asserted by an Iranian researcher, Muhsin Muhammadi, in a conference in Tehran on the “Maktab-i Shiraz” (Farhangistan-i Hunar, Tehran, December 4, 2008 : “Bakhsh-i musiqi-yi Durrat al-taj li-ghurrat al-dabadj ya sharh-i Risala-yi Sharafiyya?”), the Dar ‘ilm-i musiqi appears to be a commented translation from the Risala-yi Sharafiyya by al-Urmawi (thirteenth century); according to Muhammadi, ‘Abd al-Qadir al-Maraghayi affirmed later that al-Shirazi’s students have done this translation so that this author (then a minister of Mughul Sultan) could offer it to Amir Dabaj b. Filshah (governor in Gilan province).