I do fight feedback issues at times. I've hesitated on getting a 31 band EQ,mainly because I don't really know anything about different frequencies, and I'd hate to cause one problem while trying to remove another. EQ frequencies such a simple concept that there is some magic setting to keep it at, and only adjust the same one or two bands as needed to get rid of feedback? Like I said, we don't have a sound guy, so I hope to use equipment with very little babysitting involved.
About learning the "31" frequency bands...
Do this outside, away from any reflective walls.
1. Borrow a 31 band EQ
2. Insert it just before your power amp.
Set all EQs on mixer to flat.
3. Connect 1 SP4. Play your favorite test song in mono.
4. Adjust amp for a low, comfortable level.
5. Using Bink's test tones, play each tone in order.
6. Start with 40hz.
The SP4 will have "some" output at 40.
7. Do not boost 40.
The SP4 will come to life around 50
8. Listen to 50, 60, 63,80, 90 and 100, and adjust the appropriate EQ slider to make the loudness sound the same for all.
In general, you should not have to boost any frequency, but some frequencies will "jump out at you" and will need to be cut.
9. Continue through to at least 1250hz
I, personally, can't much hear much higher that; but then I'm 65.
I predict that there will be about 5 1/3 band sliders that will need to be cut to make it all sound the same.
You may have to adjust the power amp to keep the level comfortable.
If you do, then you will have to re-compare all of the frequencies.
10. If you can hear the effect of moving the 16k slider, you get a GOLD STAR!
11. Go back and compare/adjust all of the tones from 40-1250 until the loudness is the same to you. Do this at least 3 times. Play your favorite test song again. Crank it up.
You should notice the improvement.
Bink's test tones link: http://www.binkster.net/extras.shtml