10 ohms just seemed rather odd to me as I hadn't had much experience with the pre-80s vehicles. None that the stereo was an issue anyway. I have however seen 4 and 8 ohm quite a bit and, yes, many a smoked "what's that smell" speaker. Dangerous I imagine depending on what is around it. This effect I was able to test empirically in college physics when we studied harmonics and resonanse. The instructor, although appreciating my write up, later regretted not giving range guidelines for the speaker circuit impedance and maximum range for the variables. Learning how to make perfect harmonic resonance cavities, speaker matching, and the flammability if PC AD/DA computer interfaces was a fantastic result. I push the limits to know where they are in reality. Speakers that smoke generally are open circuit 5 seconds at most after shorting. Old amps with new speakers or new amps with old speakers (amp interchanges with stereo} isn't necessarily a problem. As long as the circuit impedance {ohms-wire to wire resistance is close enough for these purposes-rounded to tenths decimal) is in the range of the amp driving the speakers. Mismatches greater than an ohm are going to fail and vary from when it turns on to when the car is sold. So factor in Murphy's law and add how cheap the system is then multiply by system age. If it's using vacuum tubes all bets are off. Finding out the drivers range for stock stereos is a PITA. Newer speakers, newer amps it's on the box or in it every time. So changing stereo/amp (or bypassing to preserve) when upgrading speakers is a good way to safeguard while upgrading the system to make sure the car has a top notch system that more than satisfies the occupants. I feel that is a must on these {my favorite} Reattas and what they deserve. (Opinion) The baddest non Vette sportcar (2seater) of the 80's feels lame if the sound system sounds like a**t efron mismatch of an old separated cone. I am a person that sings along and cranks his stereo. So to me uprading has become second nature upon purchase. RARELY , no, never have I been satisfied with a stock setup. Paper cones can KMA. Thus it breaks down to personal preferences driving (and with a convertible the need for more decibels) and life expectancy of the system. Newer 4 ohm speakers can also be ran in series parallel combinations to quit the desired impedance. In this case a speaker matching impedance calculator simplifies the algebra for those that are not fond of variables in their math.
By the way, my 89 has to be the easiest speaker upgrade and hardest stereo upgrade to date. Amps were a snap in the trunk. I ran a fused 8 guage cable, isolated, there for power. It was the expansion of the center cassette deck section that took the most time. Not damaging the cover while expanding 3/8 of an inch took a minute. But the car loves it, doesn't rattle or squeak, whistle or creak, and is audio-isolated so well that it's like a personal concert when driving. Fear of saying to much ends this here but I hope this clarifies the queries and such a bit. Thanks for the info on GM impedance Mr. Padgett. I didn't know that to be sure.
