Please
read Part 1 and
Part 2 first.
If you have read parts 1 and 2 you will see that Audyssey had a significantly negative impact on my system.
I think there are a number of reasons.
Audyssey had trouble distinguishing a room null from a speaker problem. Then Audyssey exacerbated the problem crossing the speaker over at 200 Hz right in the middle of the range where BSC is operative. This is a big problem as the low pass crossover is fourth order and the high pass second order. So in a futile attempt to sort this mess out it applied a huge boost just above crossover and and a huge cut just below it.
The result was making a really good speaker sound like a very poor one. Audyssey could only be tricked by applying excessive BSC.
I think Audyssey has built in OCD. If you look at those curves it just fusses about far too much. I can be pretty sure all those corrections have phase and therefore time shifts.
Trying to boost a null is something Audyssey should not do. For one thing nulls are not usually highly adverse or noticed unlike peaks. Correcting nulls is bad for the health of speakers. I'm pretty sure we have a case open now on these forums where Audyssey has contributed to blowing up a number of drivers.
Audyssey keeps its details proprietary. It is not therefore possible to know what is going on. I have a suspicion that the sound of the surrounds and rear backs is specifically skewed. What Audyssey did to my surrounds and rear backs is beyond reason and adverse.
There is no doubt in my mind that it sets the sub a little too high. It did that on my last pre/pro as well. I think it is about 2 db too hot.
By my measurements, it sets the rear backs too high also. This is hard to gauge as there are multiple locations. To give all listeners the best experience I believe requires turning the rear backs down so that rear row listeners have a good experience.
On the good side it got the distances right.
The crossovers are more controversial.
This room has a null at 60 to 80 Hz which I have known for a long time. So Audyssey set the crossovers to 40 Hz. and boosted the sub. This was not a good solution as the end of the last octave was too loud, and the null exacerbated for most locations. Mine was the better solution.
Now this gets us to the thorny situation of speakers should be crossed to subs or just supplemented by them. I have long eluded to the fact that UK audio authorities in particular advise running speakers full range where possible and setting the sub to come in half an octave above F3 and then getting the level right. I agree with this. I don't think I have ever set up a system not using this plan. To me it always sounds the best.
The disadvantage is that it does not offload cone excursion of small drivers. However in the tuning range cone excursion is not usually an issue but it is below.
The big problem is the BSC of the speakers crossed over. An 80 Hz crossover is well in range of the BSC of the speakers crossed over, and will affect the speaker all the way to 160 Hz. This I'm certain is adverse.
The bass strings of an orchestra I find a badly the looser in this full crossover arrangement generally. In the last octave the ear is not critical, so I don't feel it is an issue at 40 Hz or below.
Because of this if you want to blend and supplement bringing in subs half an octave above F3 makes perfect sense.
I strongly advise you all try this at least once.
One thing I did note is that signal to noise seemed to be improved without the high pass circuits operative. Adding nose is always a penalty of active high pass crossovers.
I have already alluded to the low level set by Audyssey to calibrate Dynamic Eq especially.
Now here I think we are getting into the pop/classical divide. Any type of dynamic compressor frequency dependent or not is an issue for classical music. The problem is setting attack and release. I used to spend hours getting code/encode noise reducers right in the analog tape reel to reel days.
In terms of compressors to get a master tape ready for LP cutting for instance was a terrible problem. A lot, myself included learned the skill of manual gain riding. You see you seem to never get the attack and release times right for all the passages in the score.
Dynamic Eq was no exception. Being a skilled listener, I could easily hear it working. It really upset the legato lines of slow movements in particular. The other issue is that as volume was decreased the HF boost degraded the signal to noise on this sensitive rig that I could hear it "pumping" the noise floor which was very unpleasant.
In any event I never used the old loudness controls. I always hated them and I find Dynamic Eq worse. I would never use it. So this has allowed me to set a more sensible gain structure.
Fletcher Munson curves are essential to the audiologist but not the music lover. As the volume is turned down the sound stage should appropriately recede.
Dynamic Eq also seems to give a nasty boost to the last octave. I note when watching TV with it engaged there is gratuitous floor shaking. I think that is a sop to the "I paid good money for this sub and I want it to hit hard!"
So what is the way forward. I suspect Audyssey and like systems could be helpful in attenuating large room peaks. Fortunately I don't have any egregious ones. It should leave nulls alone.
I think if it could reliable find the F3 of speakers with fourth order roll off, then a steep high pass filter employed at that point would be helpful.
It should not be OCD and try and correct all these minute deviations.
Now one of the best features of this system is to have BSC totally adjustable. Obviously since BSC is to correct the frequency error of going from half to full space radiation, it is going to be room and speaker position dependent. My experience has taught me that very small changes in BSC have a high auditory impact. I suspect especially that the way an awful lot of center speakers have to be positioned BSC is too high. I have found that BSC even slightly too high is a major cause of poor speech intelligibility.
I would say that this is a major argument for moving to active speakers and away from passives. For many reasons a more general move to active speakers would do more to improve audio quality across the board than anything else I can think of.
Lastly employing low Q speaker designs so you don't over excite room modes in the first place is a good starting point.
So in summary I can not see how Audyssey or any similar program is likely to improve most, or any systems for that matter. Certainly in my system it is highly deleterious for multiple reasons.
I encourage you all to not follow the herd. Try when sensible to set as many of your speakers as possible to large, and try bringing in the sub half an octave above F3 of at least the main speakers. Give your system a good evaluation without Audyssey. I suspect many and probably most will be in for a pleasant surprise.