It's kind of handy to have a CD around like the "Rives audio Test CD 2". It plays through several frequencies from 20 hz to 20,000 hz. The last time I played it, I noticed a rattling sound coming from one of my 7 tweeters. I tightened the screws on it and that helped a lot.

https://docs.google.com/spreadsheet/ccc?...amp;usp=sharing