When the system behaves itself the captured acoustic of the performance takes over, as far as the ear/brain is concerned, rendering the acoustic of the listening room largely irrelevant.
This is one of the questions to which I did not find an answer: what exactly happens when the acoustics of the performance venue, as present on the recording, and the acoustics of the playback room are superposed. Is there a difference between 2-channel and multi-channel? All I know is that with 2-channel I do not have the feeling of being there, regardless of the size of the performance venue.
I have read your post with interest and would like you to sum up for us... What's your take on Room Acoustics? We all know we can't replicate Live... We all also seem to think we get close when the room is well treated. So what is your take on room treatment and which one do you favor and why?
Having read most parts of Toole’s book, and also many of the literature he refers to, I draw the following conclusions, which in part are the same as Toole’s.
1. Reverberation time
When entering a room you immediately know whether or not the room is too reverberant, no need to measure. If too high, speech intelligibility goes down, a fatiguing experience. I could not find any basis for the often recommended optimum reveberation times for small listening rooms, and certainly no psychoacoustic research to that respect, so if the room sounds ok in terms of RT60, forget it, if not, use absorption, and the normal stuff of life will do, specialized absorbers are not necessary
2. Early reflections
I could not find evidence that early reflections are detrimental as a matter of principle, in each and every case. There is some research that looks very promising, but the 2-channel, multiple reflections case has not yet been investigated. There are cases where reflections might benefit from being treated, such as strong left-right asymmetry, bad off-axis response of the loudspeakers, very low reverberation time. In any case, each case should be looked at individually.
3. Room modes
The excitation of room modes depends on the position and orientation of the source with respect to the individual mode. You cannot say that a room has a certain number of calculated modes which inevitably will be excited, regardless of circumstances.
You further cannot measure a room impulse response or such and say, there’s a problem that needs being addressed. Measurements do not take into acount the mechanisms of human hearing. Measurements are useful once you have detected an audible problem, not the other way round. Don’t panic if a measurement looks bad, it’s easy to excite room modes with broadband signals, but you listen to music, don’t you? So wait until the modes show their ugly face when playing your favorite music, then come into action. In 10 years time I have found only 3 tracks where the 72 Hz width mode is excited, but then, your favorite artists are maybe heavily using synthesizers.
My take is that the influence of the room is generally heavily overrated, the room is the last link in the chain but not by definition the weakest. Yet, this seems to be the general consensus, and when people ask for advice they almost always get to hear: treat the bass, treat the modes, treat reflections. And this without having reported an audible problem and without the person replying having all necessary data. The room and the loudspeaker/room interaction may cause problems, yes, but not necessarily.
If you also prefer multi-channel that is fine ... I hasten to say , that I am on the fence for MC as I haven't ..yet found it entirely satisfying ...and its logistics are for me cumbersome
The furniture arrangement in our living doesn’t allow correct placement of multi-channel speakers, that’s why I did not look into this technology and related acoustics/psychoacoustics at all, haven’t even heard a system.
The best thing about the Toole book is that he presents his opinions and the opinions of others that do not agree entirely with him, enabling a critical mind from the reader. As you say he shows a preference for multichannel, but accepts that stereo can also do the "trick".
I read many of the papers Toole refers to and some that Toole does not mention. When looking at the original papers in some cases the conclusions I draw are somewhat different from Toole’s and in one instance I even think that Toole made an error. I hence conclude that it is always a good idea to look at the evidence yourself and draw your own conclusions, that’s why I posted a list of literature relevant to small room acoustics (http://www.whatsbestforum.com/showt...em-and-acoustics&p=30479&viewfull=1#post30479) offering to mail the pdf’s to those interested.
Considering your comment " I never had even remotely the impression of being there when listening to live recordings" it is difficult to define exactly what is the impression of being there, as many members will happily explain you, as it is a subjective notion.
Obviously recordings can only transmit the auditory aspects of live events. A symphony orchestra is say 10-15 m wide, it is 10-50 m away, the hall has 10.000+ cbm volume, all this is not possible to convey using 2-channel. Tom Danley has some demo tracks on his website (http://www.danleysoundlabs.com/technical downloads.html), in the one with the Harley there is a plane flying over. You hear it, but it’s not 200 m up in the sky. I’v never heard good multi-channel recordings on good multi-channel systems, I’ve never heard wave field synthesis recordings and systems, perhaps that those are capable of conveying the real thing.
Klaus