Regarding The Use Of Real Time Analysis On PA Systems

05-01-2008, 11:50 PM

A real, honest to goodness FFT based system like SMAART is the only thing I would really rely on to help me analyze a system in a room, though it's been so long since I've used SMAART that I probably wouldn't be able to do anything intelligent.

A regular RTA is "deaf" as to whether a problem is rooted in a phase relationship or not - this limits their usefulness in my view.

The other problem, though, is just being confident in having taken a good set of measurements. Even with a good FFT analysis system, you can still do all kinds of wrong by just measuring the wrong way. (You can go look on The LAB forum for discussions about this.)

Tuning in the empty room to get a starting point is always useful, in my opinion. Of course, if the audience comes in and my ears tell me that something isn't right, then I act to fix it. For me, it's the Mk1 Human Ear all the way. This isn't to say that a good measurement system isn't helpful, but it isn't a cure all. It either sounds good or it doesn't - and no amount of making something look good on a display matters if the end result sounds bad or "wrong."

My case in point for this would be a band I worked for a little while back. They used one of those AutoEQ systems to get their system "flat." (I know that that's not really what we're talking about here, but still.) I have no idea of the circumstances behind how they ran the AutoEQ, but I'll be danged if the result was not one of the thinnest, most nasal, over hyped high end messes I've ever encountered. Pressing bypass on the main EQ was an enormous improvement, and I think my only baseline tweak was to put a 3 dB cut at 400Hz into the rig by way of a parametric.

The apparent result was that, when they ran their own sound (on days I was unavailable), they no longer had as many feedback problems, and felt a lot more confident about running their own mix in general. They didn't trust their own hearing to tell them that something was very "not right" about what the very sophisticated measurement and correction system had done to the PA, and had suffered for it.

This is not to say that I'm some kind of super-eared demigod - it's just to say that, ultimately, the analysis system tied directly to your own brain should win the day. (Again, only in my opinion.) Any of the big guys around here could beat the tar out of me with an analysis rig, but that's why they're the big guys - they have the rigs and the experience to make those measurements useful and helpful.