A rule of thumb I use for crossovers on ported speakers is 24 db above their low rating. So for a M80 at 34 (+/-3db), I would tend to look at something around 60 initially.

Keep in mind, most crossovers are sloped. Your M80 will still be receiving some signal below 60. What will not be happening is material below 34 staying with the M80. \:\)

Last edited by mapatton; 02/29/08 12:46 PM.
Mark
Pio 94,SB3,BD30,A35,Pio 48AV.Pronto 7000 controlling all. Getting ready for 22s, 150 & QS8s.