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Ambiophonics AES demo
The Ambiophonics volunteer team has made a lot of progress since the June
Surround Sound Conference in Banff. If any of you are coming to New York AES I hope you will consider letting us give you a real demonstration of what Ambiophonics is capable of, in a more home like setting, with new Soundlab Ambiostat curved speakers and new software. There were several things not optimum in Banff and some cockpit errors that we have since corrected. None of them were theoretical and Ambiophonics really works. Someday our own or other's implementations will match up to the theory 100% but we are really getting very close now even just since June. I have two home systems running, one with 28 speakers and the other a more affordable one with 10 mini speakers. Both with video if you like. If you come I will let you tweak things to your taste, just like you do with stereo. Robin Miller is delivering an Ambiophonic paper on Sunday and we will be around then and other days if you need transportation. The University of Parma crew are also coming and have a paper to deliver. WAVES, the Israeli professional audio company, has been measuring halls with Parma and they will be at the Convention with a hall convolver product to announce soon. We also finished the construction of the four channel Panorambiophone and used it for the first time to record the Rutter Requiem during the 9/11 services near ground zero. The conductor says it is the most realistic recording he has ever heard and he was gleefully pointing at his phantom choir members and calling out their names and this was the two channel CD rather than the four channel DVD/DTS version. We just needed one ten foot stand first row center, no spots, no hall pickups, no booms, or worry about the critical radius, etc. We expect to do a Beethoven's 9th soon. About the only way we can promote Ambiophonics as a replacement for stereophonics and 5.1 in homes is to get enough audio aficionados to hear it, like it and reach a critical and irresistible vocal mass. Right now if you are a do it yourself PC maven, we can likely get you going Ambiophonically. Please e-mail or give me a ring at 201-784-0614 if you come to New York now or anytime. Ralph Glasgal www.ambiophonics.org More technical details on progress since Banff. The new Ambiophonic system I have here now is easily far superior to anything we tried to demo in Banff using Genelecs. Soundlab, an electrostatic loudspeaker company, has fabricated for us tall curved panels (Ambiopoles) with 70 Hz and up response used with subwoofers that act as line sources. These speakers have two stators so that from the same panel both direct sound and the crosstalk cancellation signal can be launched. The XTC signal can then be adjusted in level, delay, or frequency response to get the best results. But it is the curvature and uniformity that is most important. If you set the speakers so that the beginning of the curve is flat and facing its near ear and the curve recedes out sideways, then as you lean sideways parallel to the speaker the level stays about the same but the delay increases. At the other ear the level stays the same (if you don't go too far beyond the inner edge) since you are just picking up another line but the delay similarly increases. To make a long story short, Ambiophonics now has a sweet area in width large enough so that you could fall off an easy chair leaning at its sweet edge and in-line there is plenty of room to recline or put seats in a row and watch a DVD concert video centered on the video screen Of course, if you are on a budget you can use cheaper speakers and live with a smaller sweet area. Much work can be done to test other speakers and adjust software, in this regard. Even more interesting is that the deterioration to the far side of the sweet area is very gradual, as in stereophonics, and there is no pressure at the ears at any location. Also with new Analog Devices boards, or a PC we are adapting, and software the cancellation extends from 250 Hz to over 6000 Hz (the upper limit is hard for me to tell). We do need to research even better crosstalk cancellation filters and I am sure over the years more will and could be done with even a little volunteer, mfg,. or AES, IRT, VDT, ITU, support. The next thing we have done is to add a second similar Ambiopole to the far rear of the listening seat. When playing two channel material the rear crosstalk cancelled Ambiopole is fed the same signal as the front one with about a three millisecond delay. The effect of this is to further enlarge the sweet area, widen the front stage, and enhance its apparent depth. This widening/depth effect was predicted since it eliminates (through deliberate pinna confusion) the pinna direction finding error at the extreme sides due to having direct sound speakers so frontal. That is, the high frequency signals from the rear form a pinna pattern that reacts with the same high frequency signals from the front to eliminate the frontal pinna bias and allow the side producing ITDs and ILDs to be heard with greater realism. The addtional early reflection from a deverse direction adds to the depth cues provided by the other surrounds. Ralph Glasgal www.ambiophonics.org |
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