Dave Ratt is a great engineer.
He also has at his disposal, multi million dollar PA systems and top of the range PA gear which already sounds great out of the box.
If you were to ask Dave Ratt about whether his theory is still relevant on a smaller sytem where the engineer was having to make drastic GEQ modification in order to achieve the goal, then I think you would find his answer would be… “Hell No, thats not what I meant it for”.
Senheiser make great headphones, they don’t make loudspeaker systems.
I can’t for one moment think why I would want to make my PA system sound like a pair of Sehneiser headphones where the element is 20mm away from my ears and the PA system is suspended from the roof 50 meters from me. They are fundamentally different acoustic spaces and coupling that will never sound even remotely similar.
GEQ (actually any EQ) is fundamentally adjusting phase, whenever you muck with time / phase, you muck with the sound and degade it. A minimalist approach to EQ will always yield better results. (High pass filters are different, I use them until the cows come home).
You gain far more in quality by changing mics, or speakers than you do from changing EQ to try and improve sound. EQ is a sound management tool, not a sound enhancement tool and this is what Dave is alluding to. Notice how he uses words like… correction, repair etc.
A good sounding PA doesn’t need any EQ to make it sound better, all you should be doing is reducing the frequencies that are a problem in a space. If you start using GEQ to alter the sound of a PA system to match your headphones, you are on a slippery slope to failsville. On the type of systems that Dave uses, this might involve maybe 1dB or 2dB of adjustment at a few specific frequencies, not a smiley face EQ. If you are making drastic EQ changes, there is something else wrong.
Dave Ratt has come up with some great ideas that have changed the way large scale PA’s are setup, but he has also come up with a lot of ideas that have failed (thats the nature of trying new stuff). Just because he publishes a new idea, doesn’t make it the new gosphel in live sound reinforcement, it just makes it a new idea to try and evaluate and see what works. It also doesn’t make the ideal scalable down to smaller systems. What works in a 50,000 seat arena, does not necessarily work in a 500 seat hall.
He has done some stellar work on cardiod sub patterns that I now use all the time but it simply doesn’t work on a system below a certain size.