Originally Posted by Steve Dodds
The 'after' results ARC shows are as wildly optimistic (if not flat-out deceptive) as those Audyssey shows, but the before charts seem pretty good and QM is better still because it uses one position.
Quick Measure is indended for nothing more than assisting in speaker positioning, especially the sub. Multiple measurement positions are required for effective room correction even if there's only one listening position, otherwise peaks and nulls in that position will affect results adversely.
I don't know whether you're comparing smoothed graphs to unsmoothed but Quick Measure displays an unsmoothed graph from one measurement position whereas the final ARC graphs are smoothed, and use the average as measured from from five to ten positions.
By design, ARC doesn't waste resources trying to fix narrow troughs that are inevitable in-room and likely to be inaudible, therefore the displayed final graphs - the green curves - are indeed representative of what'll be heard. If someone sends us an ARC file we can view the unsmoothed curves for each position from 5 Hz to 24 kHz but this info is not very useful compared to what ARC already shows and could very well be misinterpreted (smoothing helps retrieve information and reject noise but that's another story).
On and off, posters in the Anthem threads have questioned why we don't include a verification phase where the correction is on while the speakers are swept for a second round to see whether the final response matches the predicted correction. For one, we know that it does match and for another it would lead to some people becoming obsessive about small displayed differences which make no real-world difference while listening. In other words, it would be a waste of time.
To qualify that statement for readers I dug up some old ARC v2 results sent by jayray, a regular poster on the Anthem thread who has run practically every ARC beta from the last few years. In this beta version he stumbled on a bug where the correction was left on during sweeps. The result is shown in the second set of graphs below, the ones without green curves. The two sets of measurements were taken nine days apart so temperature, humidity, and pressure might account for minor deviations but note how closely the red measured graph in the second set matches the target and the green corrected graph in the first set. Clearly, ARC is doing everything that's intended of it here, and the intentions were determined through many years of research using many test subjects in blind listening tests, bad speakers, good speakers, bad rooms, good rooms, at Canada's NRC, in-house, and in the field. The conclusion was that this type of correction benefitted all scenarios.
As a reminder, these are ARC v2 results whereas we are on v3, the recommended correction range is still 5 kHz since the "omni" mic becomes progressively directional above that, and jayray has since moved his sub by about eight feet resulting in its in-room corrected response being ruler flat to 100 Hz. Results are posted by him somewhere in the Anthem D2v thread in case anyone is interested. The dip in response shown here at around 115 Hz in the center channel isn't fully corrected because by design there's a 6 dB boost limit at any one frequency - ARC doesn't stress speakers by trying to make them play something they can't or shouldn't play.