This one is going to be funny, well for all of you, I'll probably just keep banging my head on the wall.

I'm looking for work-around, creative trouble shooting or magical powers.

Problem(s) : 1. Reflective concrete surfaces, and minimal sound absorption material. 2. The outdated ( I think it's 28 years old) install also has clusters of dead hung speakers not producing sound. (either at amp rack or in signal chain). 3. Minimum of 7 two channel amplifiers that do not pass signal. (Still diagnosing the why)

What frequencies generally bounce of concrete? I have found 400-800 HZ to be a feedback issue. However decreasing these values takes away from tones needed to make the mix warm/pleasant for an event like the 10 graduations being hosted inside this concrete oval. Can I make up for these frequencies somehow? Is that question inherently wrong or misguided?

The dead spots in the clusters certainly don't help the reflection issue since the sound bounces in those spots.

Would hanging drape over certain areas reduce reflectivity?

I might be able to cobble together an outboard dynamic processor but I know adding delay largely won't alleviate symptoms.

I have a handful of pole mountable 2 way 12 inch boxes I am using as monitors and front fills.

I am adding 4 powered speakers to the floor for front fills. I can go into further detail on this if necessary.

I have average microphones available, mostly Shures, Beta 58a wireless capsules, wired 58's and a number of instrument microphones. I do have a Shure KSM 137. I usually use this for Mic'ing brass or string instruments but it does have qualities that (given the right parameters) could be used for voice.

The management has plans for a full overhaul and are receptive to input. I just need to get through these graduations.

I can go into further details below.