He placed singers before the altar, to make sweet melody with their voices: For altar see the comments on 35.6. The phrase with their voices is unnecessary since most singers sing with their voices. However, we may express make sweet melody with their voices as “sing beautiful [or, sweet] songs.” An alternative model for this verse is:

• David put singers at [or, in front of] the altar to sing beautiful songs.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on Sirach. (UBS Helps for Translators). New York: UBS, 2008. For this and other handbooks for translators see here.