Adveser Messages: 434 Registered: July 2009 Location: USA
Illuminati (1st Degree)
If you are using these things for voice the following should be done to put an end to feedback.
Lower the bass. make a "B" or "P" into the mic and make sure it clips on the meter to be loud enough. See that it is not "boomy" sounding. This is the loudest signal you can put through an amp/PA in my experience. This sound will clip when nothing else will. The clip meter can be blinking constantly and it won't really affect the sound.
Roll off the High frequencies. This will stop feedback. anything above 4Khz is useless for the voice unless recording an album through a condenser mic. We sense direction at 12Khz and we have a huge spike in our hearing at this frequency, so make sure this frequency is virtually muted. It will make the speaker disappear from the audiences perception.
I'm not addressing the speaker placement because feedback should only be happening with the mic pointed at the speaker and your problem extends beyond that, which is not a speaker placement issue.