Recording mics

[whaleboat]

I work at a high school auditorium and record the sound to CD from a number of performances . My question is this , why do the mics I'm using work well for recording , but not for sending the signal through the amps and speakers and into the house ? I have two Audio-technica choir mics , 835's I believe , in the house about 25 feet in front of the stage ,and about 15 feet above it . I send the signal from those mics to a pre-fade aux out and into a CD recorder and can even record people talking in a normal tone . But when I try to put the signal from my recording mics into the mix , I have to turn the gain up so high I begin to get feedback . I'm using a Spirit 4+2 board , going to an amp rated at 700 watts output with a 4 ohm load , The speakers are rated at 250 watts RMS and I'm running the amps paralled with 2 speakers on one channel and one speaker on the other . Just curious , thanks .

[yeahforbes]

Distance-miking (i.e. not 1 inch from the source like a handheld) doesn't work well with live sound. I think the furthest distance I've ever seen work well is drum overhead mics, and that works because drums are incredibly loud.

But there's a couple things that will help:
1. Move the performance back or the speakers forward. I doubt this is possible in an auditorium setting.
2. Move the mics closer to the source. This will make them pick up individual voices more than the entire ensemble which is undesirable.
3. Use mics with a tighter pickup pattern. This will have the same effect as #2.
4. Get a feedback suppressor. This is the most feasible option. I use the one in the DBX Driverack PA as well as the Behringer FBQ2496 (one of their products which is actually good). It EQ's incredibly narrow notches out of the signal (going to the speakers only, if you connect it that way) wherever feedback occurs and usually gets you about 10dB more gain before feedback.
5. Find ways to make the choir heard without amplification. If air conditioning noise is a problem, crank it before the concert and during intermission, but keep it off while they're singing. If seats squeak, get some high school kids to hit them all with WD-40.

[whaleboat]

Thanks , Whaleboat

[exclibr]

I do this kind of work all the time. The choir mics should be directly over the choir and you should have at least four of them. I actually have 16 choir mics hanging over my stage, but don't necessarily use all of them at the same time. The more mics doing the pick-up, the less gain you need on them.