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Gregm wrote:

Coming back to the "multi-driver" spkrs -- especially unfamiliar ones. It has taken me a long time to "optimise" the positioning of a pair of 4-way spkrs (9 drive-units, of which two in the back, in phase) …. One difficulty in "correctly" positioning these two in the room came fm the number of frequency bands that have to be "coupled". Simply put, moving ONE spkr 1degree front tow-in with less than 1mm movement in the back will change the phase relation in 4 frequency ranges. For example, the tweets may snap into "focus" while the mid-bass recede (phase problem).

Gregm, what you describe is very accurate. Form my point of view your description suggests that you have very accurately and very smartly built loudspeakers, however the loudspeakers built upon the fundamentally faulty design objectives. With multi-channel speakers it might be quite complicated and in many instances it might be impossible to reach the DPLOS. Even if it is possible with a given loudspeaker then the DPLOS become very fragile and appears/appears too sudden, without a gradual improvement while approaching the DPLOS. The keys are phase coherency and … surprise, surprise a compliance of the individual drivers between each other. Also, in end of 90s I spent a lot of time learning how different topologies of crossovers affect Sound. Higher order crossovers produce less “maximum amplitude” at the level #3 (my post above) of the DPLOS proximity. Any deviation of crossover from 6db per octave severely minimized articulation and expressive capacity of a loudspeaker. The impedance normalization networks and any resonating chains completely kille it. Ironically 12dB per octave coming from a mechanical device (for instance cut off due to the size of a horn bell) instead of electrical resonating chain do not affect Sound so negatively.

Gregm wrote:

{BTW, by "focus" I mean the sound between them -- not the soundstaging & three-dimensional presentation, breathtaking rendition of detail, et alia nauseating mumbo-jumbo.}

Yes, defiantly it is mumbo-jumbos but if look at this “semantic” form a different angle than there is nothing wrong with this phraseology if this phraseology actually means something. I think that problem is that year over year the army of the industry idiots: reviewers, dealers and etc… completely compromised and devaluated this semantic and today, it does sound to us as the mumbo-jumbo. For instance the estimable imbecile Michael Fremer, the senior and extraordinary contributing editor to the Stereophile magazine, was so overwhelmed with his desire to make the Audio Morons to buy a 12” peace of cheap plastic for $400 that he have written that his turntable mat was so good that being 4mm of height it practically …did not affect FTA. Another, well know Moron-dealer, who also loves to run his brain-disconnected mouth and to mill empty words, was trying to convince me a week ago that there is a way to increase output power of Class A1 operating SET by changing power mains from 20A to 30A. According to him it will make 6C33C be able to output 100W… Surely, after listening the chorus of those cretins year after year any person who has IQ higher then 50 would begin to hate the beaten audio phraseology … In context of this BS that the “audio semantic providers” dump to audio public I perfectly appreciate what Bose did in 80s taking a reviewer who wrote meaningless phraseology in court and forcing the fool to admit that his comment were meaningless.
 

Gregm wrote:

{BTW, in order to guard against accidents, I have taped the contour of the spkrs (which are usefully floorstanding).

Sure, everyone dose it. The funny part is that when we return the speakers into the previously marked position we never put then in the exact spot but a few mm off. Very frequently the “off” location is closer  (luckily) to the DPLOS then the original was. I feel the only one way to map the exact location is to have loudspeakers to sit on the hard-coupled spikes and do not mark the location of the loudspeakers but rather make the holes made in wooden floor by the spikes. Of course it is not always possible and if you have some kind of Wilson Grand Slam of many hundreds kilograms then good luck to manage the loudspeakers to match the spike’s holes… :-)

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