[HClarkx]

Wayne A. Pflughaupt wrote:

Ethan also did a simple evaluation of the effectiveness of the Audyssey MultEQ, which claims to reduce ringing. His conclusion was that it was a mixed bag as far as dealing with extended low frequency signal decay, aka “ringing” or “modal ringing.”

I recall the Ethan Winer monolog on his comparison of Audyssey and room treatments. Didn't Chris Kyriakakis of Audyssey take issue with his results and quite conclusively demonstrate that the Audyssey FIR filters do address decay? The Audyssey filters are FIR so it would seem they should.

It occurs to me that I said something stupid earlier about filters compensating room decay. One may want to adjust room decay but one doesn't want to eliminate it. Doing so would befuddle sensitive ears that expect a "real" room. I wonder though whether a filter that corrects a given peak or dip in frequency response will necessarily be altering the decay at those frequencies appropriately. I.e., is there a correlation between a dip in frequency response at a listening position and the room decay at that frequency. I'm thinking not. A reflection from a wall/ceiling near the sub can combine with the direct wave (as in Tekari's case) and cause quite a response dip, but that doesn't mean that there will be additional reflections that continue bouncing around the room at that frequency (that reflection may have come via the only solid surface in the room). If I'm right, any decay correction wouldn't necessarily be appropriate.

. . . . I’ve found pretty much the same thing as Ethan, that actual in-room measurements show that it’s a mixed bag using an equalizer as a fix for extended low frequency decay issues.

Seems there's an opportunity for some definitive comparisons of Behringer, Audyssey, and other approaches.

I wonder though, the ear must deal frequently with variations in decay. Decay may not be much of an issue if the ear/brain takes care of it. Unless maybe the decay problem is severe. I mean a boomy room is a problem, but beyond that maybe decay isn't much of an issue.

. . . . . What was apparent was that the modal filters improved ringing for some peaks REW had identified, but for others there was no improvement at all.

I think it's significant that you didn't find REW's recommendation to degrade decay. That would definitely be a negative result. At least if the improvement ranges from none to some, the results are in the right direction. But, fixing decay implies we know what decay is appropriate. Maybe we should to go london and measure the Philharmonic hall and then adjust our own decay to match it when we are listening to the London Philharmonic. Or maybe not, doesn't the recording already provide that effect? So what is the target? I think I've seen "desirable" HT decay times mentioned so presumably there or optimum ones (do they vary by music/movie type?). Can we actually hear the difference if the decay is in a credible range?

That’s one thing I have noticed here at the Shack where people (including myself) have posted graphs showing that an EQ filter improved ringing: They’ve all been short-duration 300 ms windows, not long-duration.

My guess is that if the ear/mind can be troubled by inappropriate (?) ringing, it's probably the longer duration ringing that is problematic.

You can clearly see this “fast attenuation but only to a certain level” effect with the first set of comparison graphs with Ethan’s Audyssey evaluation - note the region between 56 and 20 Hz.

I do see that. It would seem likely that the lower the frequency, the more difficult it is to control ringing. There's an awful lot of energy bouncing around to be controlled by a speaker cone. I mean after the bit of energy is sent out, additional energy has to be emitted to counter the ringing. Can a filter that only needs to make a small correction in frequency response at a certain listening position be expected to help much with a monster ringing problem at that frequency.

Ethan and John both maintain that narrow filters have the greatest effect on time domain. That’s one thing I have yet to evaluate at length, but intend to.

I look forward to that. I may download REW, connect my Audyssey mic, and see what happens when I turn my Sound EQ on and off.

Best,
Harrison