Look at omnipolar speakers (not bipoles or dipoles), such as those by Mirage. Here's a link to their site for further information.
a wide horizontal dispersion so that someone doesn't have to sit in a precise location to hear the best sound. Budget is $1500-2,000.
ATC have wide dispersion (Dome Mid) but you will need an SCM20 or more to fill that size room....so look second hand carefully ....the only drawback is you may find you lack bass...so it would not be my first choice given your budget.
Energy also devote a lot of effort to off axis response and the top of the line Veritas (again look for second hand) can certainly fill a room of that size with plenty of bass and a very even sound field (wide sweetspot) ...probably a better option than ATC.
I suspect Duke may have a speaker that also will work perfectly for you - as he takes as much time working on and worrying about a good off axis response as other designers do about chasing flat on axis - or at least, if not his own design, I suspect Duke will have plenty of good suggestions!
Second the Ohm Walsh. The 100 M3 are in your price range and with adequate power will do the job very nicely. I'm pushing 60w/ch and the speakers are rated to 150W/CH.
They throw an amazingly wide soundstage are very quick & dynamic, go down to 30 hz (in M2 cabinets). I'm a very satisfied customer. I've had them for about 2 yars now.
Try experimenting with your existing speakers. If you go with extreme toe-in, you can effectively improve coverage. If the left speaker is aimed at the viewer/listener on the extreme right side, that listener will get a loud signal from the left speaker and will be off-axis from the right hand speaker (because that speaker will also be toed-in) -- this will provide some compensation for the difference in distance between the listener and the two speakers.
Back in the 1970s, the Leslie company (yes, the organ people) designed a speaker with limited dispersion for specifically this purpose. The limited dispersion reduced the amount of signal off axis, to have the compensating effect I have described above.
>I need your advice on the best used speakers for a room that is 22 by 22 with a 14 foot cathedral ceiling. Primary listening is classical, jazz, vocal. I'd like advice on those speakers that have a wide horizontal dispersion so that someone doesn't have to sit in a precise location to hear the best sound. Budget is $1500-2,000.
You only need uniform off-axis frequency response to get the same sound anywhere in the room, although most commercial speakers are pretty bad there.
To get some semblance of imaging you need a controlled roll-off so the increase in volume you get moving closer to one speaker than the other is complemented by a corresponding decrease in relative level from the speaker's radiation pattern. This will also help retain clarity when you're sitting in the sweet spot.
Dynamic dipoles, ribbon dipoles, or wave guides toed in past the primary listening position will do that; with a pair of Orions you can get correct imaging across a 7' wide couch.
A wave guide crossed to a large woofer (as used by Duke and Earl Geddes) would be worth looking at too.
I owned these till recently, and they had the best horizontal/vertical dispersion that i've ever experienced. No toe in needed, just aim straight, and feel free to walk around. Had to sell it cuz they were big in the new living room. But listen to it atleast once if you get a chance before you decide.