Originally Posted by gtpsuper24
...what many do is gravitate towards a speaker with great inaccurate measurements instead of the one that doesn't look great but is accurate and truthful.
It's said that the two reasons for not, in effect, marketing a speaker by its measurements is that either those measurements are bad or they don't exist. There's a third: To simply not market a speaker by its measurements. In the case of a lot of makers this is deliberate.
Comparing measurements is to compare a speaker to another speaker, and only in small part. To compare speakers by listening is still to compare speakers. To really get to know a speaker over a month in your own system is the only way to compare it not to the sound of another device, but to the sound of nature.
Your ears know even if you may think you do not. You do not tell them what to hear; they tell you what they're witnessing, which is exactly why they're there. The rest of what you find published is either marketspeak or potentially informative limited data, but it's not going to tell you if you've hit your own standards in your own system.
With regard to SPL and impedance measurements, they on the other hand are pretty darn absolute. So are Ohm's Law and the nearest calibrated microphone. The terms efficiency
are also absolute as well as not interchangeable. For example, a 4 ohm woofer typically sinks double the current from the amplifier of its 8 ohm counterpart, lifting the sensitivity
of the 4 ohm part by a whopping 3dB. Their efficiencies
are tied to system size and here they'll be the same.
Impedance has much to do with loudness because it regulates current. When a modern amplifier - at least a good amplifier, which is why we always recommend high current designs - delivers twice the current into half the impedance naturally it doubles the speaker's relative volume. This may be fine and good but remember to derate the 4 ohm speaker's low power sensitivity by 3dB when comparing. Electrically the penalty is over on the loud of the volume scale, where since free lunches don't exist, the lower impedance system just runs the amplifier out of steam 3dB lower on the amplifier's volume scale. Same amplifier, very nearly the same maximum level, and no net advantage whatsoever, except that all the while the amplifier is much closer to its discomfort zone and is making what could be a lot more heat.
System size also strongly affects loudness, which is why I recommend one be aware when comparing two systems of different size, such as a simple 5.25" based 2-way speaker to a 6.5" based 2-way. The larger system always has the efficiency advantage and its numbers should show it in some realistic ratio of more F3 and more efficiency - more bass and/or more loudness at the same amplifier current setting.
Because they are complex, relative, and incomplete, measurements are not absolute to your reaction to the sound of the output of a loudspeaker. On the other hand, certain of that same speaker's important foundational parameters are reliably predictable because they relate to more elemental, numerical terms like simple relative current flow. Ohm's Law rules okay.