Where do I position 4 speakers for 3D stereo sound

Without the right processing, 4 speakers cannot do 3d sound. Heck, without the right recording, 4 speakers cannot do 3d sound. You might get wall to wall sound or surround sound from all directions, but 3d sound??? Not really... 2 channel was created to effectively provide 3d sound. And it does it well if you have the right components.

KF

Thanks your help. You have given me some good ideas. I too am a two channel purist, which is why I don't want any processors involved to achieve the effect that I want. I realize that good recordings provide a spacial effect with two speakers. However, I have found that the effect is all up front. I would like to feel that I'm involved with the music experience, not just witnessing it. Only back speakers can provide that. How to go about using back speakers is the problem. Processing two channel music through all 4 speakers is out of the question. Distortion of the original music will always be a problem, regardless of the quality of the processor. However, I never considered using a processor for only the rear speakers. I can now feel the gears grinding in my head.

Let me now bring up another series of questions. Which processor would be best for creating spacial ambiance through only the rear speakers using today's technology? Where should the rear speakers be positioned while using the processor? Is rear speaker distance to the sweetspot important?

In my very,very,very (did I mention how very) humble opinion you are embarking on an excericise in futility.

"However, I have found that the effect is all up front."

This could be how it was recorded. High-fidelity (faithful to the source) is one thing, special effects are another. You're basically doing surround sound with music, some discs have far more material on them for this endeavor than others.

"Which processor would be best for creating spacial ambiance through only the rear speakers using today's technology?"

Depends on the recording. There are Dolby Surround Music only recordings. However, you'll probably get the most mileage with one of the generic matrixing type devices to turn two into four--I can't remember who did what off hand. It could add some neat effects, but I'm not sure you're necessarily going to step into a concert hall with it. Ambisonics requires 4 or 5 microphones to do a proper recording w/ ss music.

You will have a rough time with the people here on the 'Gon with almost anything but two channel, analogue/vinyl tweaked out systems, being fed reconstituted power through special ac cords. So there I said it, again. Do I fell any better? No, not really. Briefly, just looked at the current issue of the British magazine "Hi-Fi +" on the newsstand today and, lo and behold, a new multi-channel decoder or enhancer or whatever ( I didn't actually read the article and was too cheap to buy the mag, preferring to spend my limited money on records instead) made by Dynavector. Interestingly, the ambiance channels seem to be on the sides of the room, somewhat next to the listening position, but, it seems, pointing forward, towards the main speakers. So, you see, your notion that, somehow, the sound would have more depth with four rather than two speakers, positioned fore and aft, actually makes so much sense that one of the most respected cartridge manufacturers has decided to come out with this type of product. I don't know what to tell you as to what may be available between what I have (and may put back in the system soon enough) which is no longer made and going the multi-channel SACD route, which may very well be premature. Since I have never been into 5.1 home theatre, the Dolby decoder, whatever it is thing, is a total unknown to me. Yes, I have lived through some kind of audiophile eclipse. So now, maybe, you can look up what Dynavector proposes, it might be the ticket for you, and don't let the buzzards get you down, it's your system to set up the way you enjoy it. The same nay Sayers would be saying nay about stereo if we set the clock back to mono days.