The main point of my first post was my view that a 'better' room correction system like Dirac did not make a really
big difference when compared to YPAO. Floyd Toole and others have pointed out that the hearing system operates in frequency bands which minimise the perceived level of sound. Getting it roughly right is usually good enough for things to sound good.
I've noticed that several posters on this thread were happily using the YPAO Low Frequency setting, which does hardly anything to correct the room. Though running YPAO does the most important thing - which is to set the timing on all the speakers.
Though, after saying that the Dirac didn't make a big audible difference to the frequency response, why the hell did I spend thousands on it? Am I a complete divot??
It pleases me to think I'm not totally daft. Dirac does do something else to the sound.
Now this is totally off topic to the A8A but here is an experiment. I connected a PC directly to my DDRC24 Dirac box, which then output to an amp in 'pure direct' mode to my right lounge speaker. I then ran frequency sweeps in REW , one with Dirac on and the other with no room correction at all.
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Now my right speaker is flat to +/-5dB (80Hz-20kHz) at my listening distance of 11 feet without correction. Dirac changes that to +/-3dB. Though very difficult to distinguish by ear. So it isn't that which makes things sound different withDirac On or Off.
This is the Impulse display without any room correction -
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And here with Dirac ON -
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Now I don't know exactly what they are doing to the signal to get that difference, but it does actually sound clearer.