Dear All
May I digress temporarily from headphones.
Really good comments. In regard to the center speaker being the only way to create depth and enhance positioning (Bell labs in 1930's), yes but not really. Turns out that a number of years ago we at Involve did a study to examine why a good testing speaker can sound bad and a bad testing speaker can sound good. My initial theory was that it was going to be something related to the impulse decay response but I was wrong. We tried to correlate all the standard test parameters to perceived sound quality....you know, frequency response, thd, imd, tone burst, polar response. And in reality none correlated (except polar in a sense).
"Overture" and I were both stunned and confused by the result, we both sat down (on the floor actually) and then it struck us that the prime factors may have been more obvious. When we looked physically at a "good" sounding speaker vs a really good testing bad sounding speaker it became more obvious.
I will let you guys on a little secret: The differences were regarding what I call concentricity and the front back polar response. Turns out that 99% of the speakers we buy are WRONG! We constructed test jigs with test audiences on blind trials and found when all drivers were moved to be concentrically placed as opposed to the usual up/ down tweeter/ mid/ woofer placement the audience response was dramatic with ALL positively preferring the concentric placement- it was not subtle. We tested time alignment- and that is bullshit.
Next we constructed jigs to test radiation patterns comparing monopole (front firing)/ bipole/ dipole and again the audience preference was dramatic with almost a universal preference to DIPOPE, the least preferred was monopole. Again it was not the usual audiofool subtle stuff, it was in your face.
The real difference using concentric dipoles was a greatly enhanced sense of depth and vastly improved imaging and separation of sonic objects. All tests were conducted with conventional cone speakers. This was an interesting result as 99% of all speakers sold are non concentric monopoles!!!!! This was even more interesting as we are and were manufacturers of electrostatic loudspeakers (see Nakamichi dragon electrostatic and our kit partner
www.eraudio.com.au and
http://www.hifizine.com/2013/03/the...ew-with-charlie-van-dongen-and-rob-mackinlay/).
Guess what- electrostatics are concentric dipoles- the answer was staring us in the face all the time!
This is what I was getting at in my previous post that the best solid stereo images with depth I have experienced have been with STEREO electrostatic loudspeakers, that was the reason I got interested in them in the mid 1990's. Imaging and depth with 3 speaker solutions have always been vastly inferior.
So part of my point is the current "pissing contest" on more and more channels is based on faulty logic and test results of say the 1930's conducted on speakers that were frankly wrong for serious imaging. If you ask me later (very nicely) I could explain why concentric bipoles produce thus superior imaging.
This is my point with headphone - and certainly no disrespect to Smyth who I believe produce a truly excellent product. Claiming 16 channels is essentially meaningless. Consider the results you get from (inner ear) personal recordings on dummy heads and played back inner ear.....its TWO CHANNEL.
Getting back to headphones. As I stated previously the problem with headphone surround is removing the in head sound and creating an effective frontal image, back sides is actually much easier. The real trick is to do it with all heads torso shapes and ear shapes (Smyth do the multi user thing well apparently). Localisation of frontal image is a complicated thing as there is no left/ right time delay discrepancy to help in working it out. It is more concerned with that frontal flap of skin blocking your ear hole and the relative micro time delays from direct/ reflected paths around this flap plus the frequency contouring of the frontal image. As a note, tests have shown that in an anechoic chamber users have difficulty in determining frontal distances and essentially the perceived distance is shortened considerably. This implies frontal imaging is heavily reliant on reflections and the relative time arrivals of direct to reflected sound and their sequence.
Any way "Overture" or as we know him as "Dave the Bitch" is currently working on such a headphone surround device coupled to Involve surround decode, so you get 2 channels in surround headphones out. Cannot guarantee if it will work (and on all heads) but we are getting encouraging results. The product will be pitched at a lower price than Smyth buy not at the 5- 16 channel market.
Wish us luck, we might succeeded.
Regards
Chucky