ampdoc1 wrote:You will not get any reading on your DVM if the speaker is blown.
Generally speaking this is true but not always. I guess it depends on the definition of "blown". If you "bottom out" the voice coil in the magnet and cause a mechanical separation and the speaker still makes sound but rattles and pops, you will still get a reading if the wire in the coil is not broken/ still has continuity. I only state this because you can take your meter with you to buy a used speaker and it may be "blown" and still read 8 ohms or whatever. You may not know until you actually play through it with some power once you get back home. I learned this the hard way when I was younger.
As far as the battery test goes, I usually us a 1.5v battery to check for phase but have used 9v as well. Never had a problem.
Update: Thanks for all of the suggestions. I was getting ready to test the wires coming from the voice coil and noticed a very tiny tear, like a flaking of the paper cone near where the wires connect. As I pushed on this little flake to press it against the cone the entire cone raised exposing a complete separation just above the spider. To the naked eye you couldn't see any problem, and pressing on the top of the cone on first inspection the cone still moved with normal suspension. Unfortunately, just a case of a vintage speaker at the end of its life.
