Pay attention to the placement of speakers. For one, don't try to use mics
in front of speakers. The talker needs to have a zone and loud-speakers
should not "talk" to that zone. People near the talker don't need to have
loud-speakers to hear him/her, so if there are some, disconnect them. They
should also "point" where the sound is needed, not oriented because the
mounting is easy. You have to walk around and see where the loud-speakers
are needed and have them there, but not everywhere. I obviously don't know
if this is the case for you, but churches tend to have PA systems thrown at
them rather than designed.
You can "notch" the preferred frequency, for a few db of feedback margin,
with an equalizer. However, when you notch the primary frequency, the next
pops up a few dB down and you can keep chasing them until you have reduced
the gain all thougth the spectrum. Plus, just move a foot or two and the
path changes and the preferred frequency changes.

I am unfamiliar with DSP feedback eliminators, but the job should be easier
if you start at the source (of speaker / mic proximity)

73, Steve, K9DCI



"James Thompson" wrote in message
...
Has anyone got a good but cheap circuit to eliminate or surpress feedback.
Im making my son some low power fm mikes to use in his church, but they
get
feedback real easy. Is there a simple notch filter per say that I can add
the the mike section of this. My pcb is only 1.5 by 2" right now.
Thanks.