Originally Posted by Soulburner
I think these room correction processes are learning much more about the speakers and the room than meets the eye.
Your post is good advice. However, I question the above remark based on what I have experienced.
I have one of the most powerful and expensive multichannel processors on the market, widely praised for its processing power and complicated signal processing. It is enormously flexible, clearly designed by smart people in the math and DSP categories, but equally clearly these people did not understand the acoustics and psychoacoustics of loudspeakers and rooms - my speciality. The result is that, in its self-calibration mode it does things that should not be done.
I won't go into the details of my history with this unit, but it began with a setup procedure, using their proprietary microphone, spatial averaging with weighted mic locations, and allusions to combined IIR and FIR processing promising a very special result.
It was indeed special, because the superb sound of my Revel Salon2s was clearly degraded. Measurements I made with REW disagreed with the unit's displayed result, but agreed with my ears. With help from a product specialist, manual EQ overrides were able to restore the essence of good sound.
Some subsequent fiddles have taken it to the point that I can enjoy programs, but only by overriding or disabling some of the internal processes.
I know that there are other digital equalizers with problems. All originate with clever math/DSP engineers doing things that may make academic sense, but that pay insufficient attention to the peculiarities of human perception. At professional audio gatherings I have had extended discussions/arguments with some of their engineers. It has always come down to opinion, not fact, and the opinions are inclined to enhance the customers' perceived value in the product. It is part of a mighty struggle to be different or distinctive in a product that delivers something that nowadays many people can do for themselves with off-the-shelf DSP, free measurement software and a $100 mic.
None of these processes are supported by published double-blind subjective evaluations. Tell me if I am wrong.
The universal availability of "room EQ" is now a kind of "disease" in audio. People place trust in these devices that is misplaced. As I have stated several times, when the operating manual of the "calibration" device basically states that if the customer does not like the sound from the default target curve, then change the target curve. At this point it becomes a subjectively guided tone-control exercise, not a calibration. The "circle of confusion" for whatever program used during the tweaking is now permanently installed in the system.
All that said, equalization is part of the necessary treatment of room modes in bass. There is no escape from that, but even there, something that should be simple is sometimes compromised. Chapter 8 in the 3rd edition.
Toole, F. E. (2015). “The Measurement and Calibration of Sound Reproducing Systems”, J. Audio Eng. Soc., vol. 63, pp.512-541. This is an open-access paper available to non-members at www.aes.org http://www.aes.org/e-lib/browse.cfm?elib=17839