Why does it say "la'Menatze'ach bi'Neginos"?
Rashi: David established this Mizmor for Leviyim to sing it on the Duchan 1 . 'Nitzu'ach' applies to people strengthening themselves in Avodah - "Lenatze'ach Al Meleches Beis Hashem" (Ezra 3:8).
Radak citing Shocher Tov: The Mizmor was said with three kinds of praise - Nitzu'ach, Nigun (instrumental music) and Mizmor (singing) 2 . Menatze'ach (choirmaster) was [appointed] over the singers. [The Mizmorim] were given to the Menatzechim, and they gave them to the musicians and singers. No Mizmor is 'la'Meshorer' or 'la'Menagen', only la'Menatze'ach, and also in Chabakuk (3:19). We find "Lenatze'ach" in Divrei ha'Yamim (I, 23:4, 15:21). Neginos and Sheminis are Kelim on which he conducted. Each song was said on the Kelim, according to its tune. It was a great 'external' Chachmah, to arouse the Nefesh of Chachmah. The instruments in the Mikdash were lyres, harps, cymbals, trumpets and Shofar 3 . There were different names for the [instrumental] songs - "Alamos" (ibid., 20, below 46:1), Neginos (e.g. this Mizmor), Maskil, Michtam, Shigayon, Nechilos, Shigyonos and Gitis. Some instruments were called Asor, Ugav 4 , and Minim.
Pesachim 117a: When it says [both] 'Nitzu'ach' and 'Nigun', it alludes to the future.
Me'iri (Midos 2:3): The Duchan was a ledge at the beginning of Ezras Kohanim.
Radak: We find "v'Arba'as Alafim Sho'arim v'Arba'as Alafim Mehalelim la'Shem ba'Kelim Asher Asisi Lehalel" (Divrei ha'Yamim I, 23:5). We do not know whether the ones who held instruments sang, or if others sang. It says "veha'Leviyim bi'Chlei Shir
