You said, "Maybe it is an energy related thing. Maybe after x number of hours of receiving vibrations (therefore energy) from the amp the cones get their final arrangement at the molecular level !?"
My response is, not likely. Only during extreme temperature swings (hot or cold) should the molocular structure be effected. Vibration could alter the molecular structure, but for the levels I'm talking about to occur I think worrying about the cones would be the least of your problems. :-)
Maybe you overlook the obvious. To listen to the new BDR feet, you had to move the interconnect, speaker wires and power cable. Perhaps you even disconnected the AC for a brief period. All of these could be responsible for the big change in character in your system.
No, you are not nuts, just clearly concerned with hearing what you did not expect.
Just a thought, and I may be way wrong. But did you move any wires when you changed the cones? Did the cables touch each other in any way? Try lifitng all cables, power cords, and conditioners off the floor and off each other.....I noticed a major improvement when I did all of the above. I think you might have disturbed a balance you had when you made the change and if you could find it again then compare the cones and you may hear the difference...Anyone else have any idea what may be happening? Now if it was Canadian beer, I would understand, he, he....let us know what you find, cheers, Bluenose
Did you place the new cones in the identical place as the old ones? Often, small changes in position of cones under components leads to significant changes in sound.
You might try reverting to the original cones just as a sanity check?
Flex's question is also valid here - moving cones closer togther can soften & warm the sound, while moving them further apart can increase detail at the expense of warmth. I do this intentionally when tuning, even a 1" difference is noticable.
I find the very act of putting tweaks in place can give pleasure, if you're expecting a better sound, by getting one's blood flowing via the creative act of positioning the tweak and expecting a result.
or, alternatively, tweaks may detract from the sound, if the sound was good before and you had settled into a bliss before the tweak (thereby ruining it by getting all analytical and getting up to change something)
of course it is possible that the specific tweak is solely responsible for the change. but usually it is the interaction between tweak and tweaker (and ear).
marcandr: no, i think there are more than 4 nuts like you and yours, tho some are rumored to be imprisoned on uranus. i suggest you all get together again, plug a digital clock into the same outlet occupied by your toaster and see if you can discern a difference in the inner detail of the upper mid-range of your speaker output whilst listening to the 4th of bachs brandenburgische konzerte. if you don't hear this most important phenomenon, none of you will likely make the grade as a reviewer at s'phile or tas. but then, for such a positive return on your karma, you might add a page to your thanksgiving homily. -cfb
First, thanks to all for your answers. But, I feel necessary to add the following informations.
To Argent: Maybe molecular structures could-in fact- only be altered by extreme temperatures but what happened reminded me of the differences one can hear between a brand new interconnect and an identical one with several hundred hours of burnin (playing music). I can clearly hear the differences when A/B ing them and we still are not talking about extreme temperatures. So, maybe what's happening is similar. I have no idea.
To Albert Porter: I didn't move the interconnects, the power cord or anything else nor did I turned off the power amp. If I would have done so; me or one of my fellows would have noticed and that is why such a difference stunned us all. The only thing I had to do was to lift the amp I'd say to less than 1/4 of an inch...
To Bluenose: As you see I didn't move a single wire. All my cables are suspended and not crossing each other. I (we) certainely can't see how I would have disturbed the balance. And, being a Canadian from Montreal I certainely know about canadian beers...but it was not one of those night... ;-)
To Flex: My amp is marked with little dots (stickers) underneath it in order for me to put my tweaks at the exact same places. As you said, small changes in position of tweaks can make an audible difference.
To Bob Bundus: We did the "sanity check" i.e reverting to the original cones and vice versa with always the same results with the new set: a harsher, thinner, more up-front and less musical (coherent) sound. A little (very little) sibilance was also notice.
To all: Again thank you for your comments. With the new details I just gave the question is still valid but I am starting to wonder if a mistake could have been made at BDC i.e maybe a pair of MK IV were marked as MK III ?
To Tacs: I (we) was not expecting anything. As I had a new set, it was time to give my friend his set back and replace it with mine. That's all.
I find your other points interesting as we tend to expect sound differences when tweaking. Still it was not the case this time. On the other hand, we might have been distracted from the music because we were -in fact- settled into a bliss. Interesting theory. I just guess we were distract big time then.
I thank you for your intelligent comments you had (and have) me thinking ;-)
Cornfedboy: Thank you for your positive feedback...it was exactly the kind of answer I was looking for...the toaster thing could have been helpful...but I already tried it and found that the difference was more important in the lower midrange (more delicacy) especially on track 5 of Ottmar Liebert's Nouveau Flamenco...
Please let's respect and not ridiculise each other. I was just sharing an audio experience with you all. Isn't it one of the main reasons why audio forums like this one do exist ? That being said, I still have a good sense of humor...;-)
marc: i meant no disrespect and thank you for your ackowledgment of my mere attempt at humor. i do, in fact, applaud your enthusiasm in finding yet another pathway to better sound. -cfb
Corfed. your post WAS funny...thanks again.
Tacs, I think you nailed it: expectation bias hoodwinking!