Usually a foot or two suffices for direct view sets. Usually not as far for RPTVs, as the crts are way down at the bottom front of the set. IT's easy to move the speaker near the set and see distortion (dont do this for more than just a moment). I'd make sure you're well past the point at which there is no distortion, as playing loud music will create added fields as well, which will increase the effect (and distance). It's one of those logarythmic type dealies, so the effect RAPIDLY decreases with distance. Sorry, i'm very happy NOT to be taking math .
I'm using unshielded Paradigm Studio 100's and they reside about 8 inches from the sides of my Pioneer Elite 53" CRT RPTV. Not the best location for imaging, but there is no adverse effect on my display.
Thanks for the responses. I'm contemplating buying some 125 watt Quest QT660 speakers. I'll probably have each of them at least 2 feet away from the 52" RCA RPTV, so I think that should be good enough.
That's a fine safe distance if they're unshielded. The major contribution to the field is from the magnet inside and it's strength drops off according to the inverse square law...double the distance is one-fourth the strength. At around 2 feet, the strength of the field is approximately the same as the earth's magnetic field.