speaker drivers; where to purchase and which one's?

Try madisound.com

Not sure what drivers you have but check out zalytron.com they have a large selection of high-end drivers and if they have it you will not find a better price anywhere.

The two choices they gave you are very good but you can also try Partsexpress.com they carry items from companies like Dynaudio, Audax, Morel, and Scan-Speak. From the two choices they gave you, you can get a free catalogue. Also from Parts Express but there internet site is actally better than the catalogue. Good luck on your project and building loudspeakers is much more fun to me than going out and buying them.

Question . . . is there a way to determine if the speaker drivers are within factory specs? I own a older pair of B&W 803 Matrix speakers and would like to find out if the drivers are all OK. They sound find, only a little thin in the bass partly due to my small listening room. Thanks, Joel.

to answer Joel's question, you could probably send them to a place called meniscus audio. I don't remember their number but they have a web site. If you know what the driver's specs are they could probably run some tests on your drivers and find out what all of the electrical parameters are. But there is always a production variation with almost all loudspeakers and they probably won't be dead on with the manufacturer's specs anyway. I personally don't think that there is anything wrong with your speakers though. You just might want to get a small subwoofer to boost the bass of your system. Hope that helps