BTW-for a historical point of reference from my "mental archives" the very first mutlichannel "surround" type system was a combined effort of MIT/sound associates/Acoustic Research (from memory folks so may not be
exact !)
It consisted of 16 channels per side (!!!!!!
) plus main stereo pair with each two pair set having a preselected digital delay and high frequency attenuation that simulated that position in the "artificial concert hall".
this event was reported on by all the major electronics and audio magazines of the time and even popular mechanics if memory serves,with a promise of a "simplified" consumer version to be announced soon.
This consumer adaptation was the Audiopulse model 1 Digital Audio Delay Line.
rather than even
attempt to convince the public they needed a total of 18 loudspeakers this new device instead used a tapped digital delay line for the additional channels and crossfed the signal from the left delay output to the right channel delay line input and visa versa.
The "taps" were discrete amounts of the overall selscted delay which could be from 50 ms which meant an acoustic path of 50 feet to 200 ms (200ft).
the main selling point was you only needed to add another stereo amplifier and two more loudspeakers to use this new device and with Quadraphonics being a relatively recent failure most already had these banging around the house (well most audio geeks anyway
)
In addition there were low pass filters to simulate the rate of high end attenuation that would take place in a concert hall as the sound would travel a distance,the known rate of attenuation found in any pro sound manual and used for audience coverage when setting up for a lrge arena so there are no dead spots.
anyway...
the combination of crossfed signal,discrete taps along the delay to simulate the former 16 actual speakers (now down to 8 per side taps from memory) and the filters when recycled to the input of the other channel produced the effect of sound decay and reinforced treble attentuation so each pass would be lower in level and because it was being filtered again and again and agian would have less treeble each time until the signal finally fell below the limits of audibility.
And it was expensive in the "real dollars" of the time so audiopulse came out with a model 2 that was less sophisticated,had easier to use controls,included a rear channel power amp of 25 WPC (pamp front end,discrete output stage) and something called a "2-CH Mix" which in reality was a line level output that mixed the main left and right stereo signal which formerly was not touched by this new box (straight stereo fronts,delayed rears) with the output of the delay channels and some of us looked at this and right away ran for our headphones !
Hell yes it was cool ! cool as it comes yet eventually when the novelty wore off it was back to two channel stereo for most listening.It just sounded WRONG even though it sounded
cool for most music.there was an esception though.Live Recordings !
Like with the passive Hafler Dynaquad circuit if there was already content accidently prerecorded on the disc,a natural L-R signal picked up by the microphones after travelling to the side and back walls,bouncing off then phase reversed going back to the open mics,this device like the hafler device reproduced it !
This was/is no gimmick because nothing not already there was added to the sound but only signals already present and previously hidden could be extracted and combined with the raw stereo signal for a more realistic holographic experience !
Other manufacturers seeing the potentials and the success of the two Audiopulse devices just HAD TO come out with their own versions but this being high end audio were not happy enough to copy a good idea and instead had to "improve" on it with the results of totally screwing it up and making the entire class of audio add-on device gain a reputation as something that sounded FAKE ! That they did motre harm than good and they all dissapeared never to be seen again and joined Quad on the audio trash pile of good ideas gone bad.(I still have ay model 2 aftr all these years and you will have to pry it from my cold dead hands before i give it up willingly
)
So we had Dynaquad,matrixed quadraphonics,discrete tape and CD-4 phono discret quad,then the ambience recovery devices such as the audiopulse which some idiot decided to mutate into ambience
simulation devices with disastrous results for them all and in the end to the trash heap !
Then Dolby Surround comes along,shortens the delay time.adds a center dialog channel to lock voices to the TV screen and instead of aiming it at audiophiles and music instead targeted the living room and the TV set !
Genious ! It worked and the entire family was for the first time able to take part in the new "toys" because everyone loves the movies !
It worked because it was targeted to a proper use and that did not and does not include artificial music FX but did the industry learn anything by both the failures and the only success story ?
HELL NO !
they are still trying get us us to buy into music surround even though all the evidence says we are no buying in unless FORCED to by having no other choice (see my above post
)
So what does this have to do with headphone crossfeed networks ?
Nothing and why the DSP angle is a wrong headed one.It will not be simply an attempt to make the headphones resemble the loudspeaker experience (as the present technology does) but as those touting the DSP path have said will be BETTER !
and that is why it will fail............and always has.......
