Notes: all of the 3/4" models have very little off axis droop. You can see the differences between a full dome, phase plug and 3/8" horn loading on the Dayton model. The Seas 27TBFCG has a clear plastic phase shield under the hexagrid, which vastly improves off axis response for a 1" dome. Obviously, when you listen to a tall ribbon, you might want to sit down and not move. The 3" full range is thrown into this comparison for good measure.
 
The importance of top octave response is highly overrated. It has absolutely nothing to do with sound quality, and everything to do with flexibility of placement. Simply, all it means is that you might want to toe larger drivers inwards. I say "might" because the usefulness of a response that's flat out to 20kHz is also overrated. While a peak at 10kHz is easily heard, (tape hiss anyone?) a few dB down at 10kHz is barely audible, and in some cases preferable. At the very top end, 15dB down at 20kHz is barely audible if at all. This is probably why many people don't mind tweeters like the Dayton RS28 or the many of the Morels, such as the MDT20. Dips in response at the extremes of audibility simply aren't very audible, even for those who still have clinically proven hearing out to 20kHz. (I'm good to about 18kHz in my old age)
 
System power response at and below the crossover is much more important than top octave off axis response. This is something to keep in mind with 3/4" tweeters that require substantially higher crossover points. Horizontal response may not be so bad, with only a mild null to deal with based on the woofer's diameter induced rolloff, but the vertical off axis response can have deep nulls that set in at a shallow angle if the crossover point is relatively high. What's not obvious to many folks is that vertical off axis nulls are still audible on axis. That's pretty much what power response is all about, and why it exists as a valuable measurement.
 
The most important criteria in selecting a tweeter is the harmonic distortion on the low end near the crossover point. This is the most audible defining characteristic of a tweeter, more so than top octave frequency response. System power response, while critical at the crossover point, becomes a non-issue higher in frequency. This is simply because the room plays less of a roll in the reflection of high frequencies back to the listening position. There is a lot of high frequency absorbtion in typical room construction, and even painted drywall almost completely absorbs a 15kHz tone. So, as I mentioned above, if you can toe in a system using a larger tweeter, all is well.
 
If this article sounds a little biased against 3/4" dome tweeters, that's because it is. In most cases, I see absolutely no reason to use a 3/4" tweeter, particularly with larger woofers. The only 3/4" tweeter I've used on this web site was selected based on cost and the fact that the woofer used with it was small and had a very extended response. Maybe someday someone will create a 3/4" dome that can hang with the 1" boys at the low end, but for now it doesn't exist

Summary
Not surprisingly, Fs and Vas were the parameters that drastically changed as the temperature changed. At zero degrees, the speaker practically had no resonance and output below 200Hz was non-existent. The top ends of the response curves changed only slightly, with the breakup and damping shifting around a bit.
 
The bottom line: Car audio is a difficult proposition unless you live in a place where the climate does not change much. Even with the car's climate controls working to keep the driver warm/cool, car door speakers are close enough to the outside of the car that they are still affected by outside air. I think this loss of climate control is part of the reason why I lost interest in car audio. And of course the other part is acoustics so terrible that I really see no point in wasting time with it.

Summary
Not surprisingly, Fs and Vas were the parameters that drastically changed as the temperature changed. At zero degrees, the speaker practically had no resonance and output below 200Hz was non-existent. The top ends of the response curves changed only slightly, with the breakup and damping shifting around a bit.

Summary
Not surprisingly, Fs and Vas were the parameters that drastically changed as the temperature changed. At zero degrees, the speaker practically had no resonance and output below 200Hz was non-existent. The top ends of the response curves changed only slightly, with the breakup and damping shifting around a bit.

Summary
Not surprisingly, Fs and Vas were the parameters that drastically changed as the temperature changed. At zero degrees, the speaker practically had no resonance and output below 200Hz was non-existent. The top ends of the response curves changed only slightly, with the breakup and damping shifting around a bit.

Summary
Not surprisingly, Fs and Vas were the parameters that drastically changed as the temperature changed. At zero degrees, the speaker practically had no resonance and output below 200Hz was non-existent. The top ends of the response curves changed only slightly, with the breakup and damping shifting around a bit.