what would be your opion??? what would sound nice and be pretty loud: 6 1/2" 3-way infinity kappa 63.7i 75 RMS OR 6 1/2" Alpine SPR-17LS 70 RMS thanks trying to plan out my future system with the little money i have.
The Infinity's would sound the loudest and possbily best because they have a higher sensitivity(95dB) compared to the Alpine's (87dB). Even though the Alpines have a bit wider of a frequency response, the human ear probably couldn't decipher the difference.
I read somewhere that sensitivity ratings tend to be leaning more towards bass coming fromthese speakers, thus making the ones with lower sensitivity the ones with a more true sound. If this is so then I would have picked the Alpines since a sub is going to play the bass, assuming here that you are getting that as well.
On a side note, Infinity's sensitivity is misleading. They tend to use 2.83V instead of 1 watt, and they do the testing in a car instead of an anechoic chamber (open room). Usually it gives the speakers a 5-6db advantage.
infinity uses volts rather than watts? wtf is that? 2.83V should be used for 8ohm speakers. Since we're speaking of 4ohm speakers 2V should be used. It should be closer to about 3dB difference. Either way it shouldn't really make a difference because once you add amps to give these speakers juice you won't even notice. My vote is for the infinity's but i'd go with a component system (I did).
It's the combination of using it in a car and the 2.83V reading that gives the speaker a 5-6db advantage, cabin gain helps them a lot. Usually readings are 1W/1M in an anechoic room, with the speaker infinite baffle.
About sensitivity, though, I really don't consider it a plus in nearly every case I've seen. If we were in the 80s and early 90s when power wasn't so cheap, sure I could see efficiency taking more effect. Usually a higher sensitivity comes from lightweight parts, such as metal cones, foam surrounds, loose suspension, and so on. It can also be caused by an overly strong motor assembly, overdamping the driver and causing a boomy performance. Could also be due to higher inductance from the voice coil. The usual problem is that a speaker that is extremely efficient is in most cases poorly damped. The lighter the cone, the more stiffness to mass, the more resonant the material is going to be in most cases, examples are metal, kevlar, carbon fiber, and similar materials. Those type cones tend to offer more clarity due to less cone distortion, but they tend to have nasty resonance peaks in the response that usually requires a notch filter to level out if you don't cross it over low/steep enough. Likewise, mids with a really tight suspension (less efficient) tend to trade off low bass performance for upper midrange clarity.
ah... i see. You seem to have your sh*t together. That would explain why most high-end woofers (5.5" or 6.5") add virtually no bass.