A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
psa 150:1This is a suitable doxology for the whole book, reciting the "place, theme, mode, and extent of God's high praise." (Psa 150:1-6)
in his sanctuary--on earth.
firmament of his power--which illustrates His power.
psa 150:2mighty acts-- (Psa 145:4).
excellent greatness--or, abundance of greatness.
psa 150:3trumpet--used to call religious assemblies;
psa 150:4organs--or pipe, a wind instrument, and the others were used in worship.
psa 150:5cymbals--suited to loud praise (Neh 12:27).
psa 150:6LIVING VOICES SHALL TAKE UP THE FAILING SOUNDS OF DEAD INSTRUMENTS, AND AS THEY CEASE ON EARTH, THOSE OF INTELLIGENT RANSOMED SPIRITS AND HOLY ANGELS, AS WITH THE SOUND OF MIGHTY THUNDERS, WILL PROLONG ETERNALLY THE PRAISE, SAYING: "ALLELUIA! SALVATION, AND GLORY, AND HONOR, AND POWER, UNTO THE LORD OUR GOD;" "ALLELUIA! FOR THE LORD GOD OMNIPOTENT REIGNETH." AMEN!