This is so much fun. I'll bet 15 hours of fun this weekend and I just want more and more. A question for the knowledgeable. I'm pretty sure Louis stated these was 95 or 96 dB sensitive, but I read that both the HO monitors and the xrs HO floor-standers is 99dB. I might be wrong but i want to ask if size of cab can influence on sensitivity, or other factors? Of course there is an opportunity that I remember wrongly
The Alnico speakers were originally listed as 93dB and later revised to be listed as 95dB. Depending on how we measure efficiency, they may be 93 dB (if measured from 100hz to 10khz) or they may be 95dB if measured from 300hz to 10khz. It depends on how specific we are in defining our measurement terms.
If we now add a second driver below 200hz as in the 1.5 way speakers, we are adding an additional 3dB in efficiency below 200hz, but the efficiency will remain unchanged above that frequency.
This can be can be confusing for a number of reasons. First is the difference between speaker efficiency and sensitivity. The former measures the effectiveness of converting electrical power (watts) into acoustical power (dB). The latter measures the effectiveness of converting a voltage signal (e.g., 2.83V) into acoustical power (dB). The distinction is that when speaker impedance is halved and voltage remains unchanged, we are actually delivering twice as much power (+3dB) to the speaker. Simply put: one watt = 2.83V into 8 ohms. However, 2.83v into 4 ohms = 2 watts. In other words, if the 1.5 way speaker is 99dB/2.83v/1m and it measures 4 ohms, it is really a 96dB/w/1m speaker. My feeling is that the Alnico 1.5 way speakers are a legitimate 95-96dB/w/m speaker over its musical frequency range.
The 1.5 way speakers should be the same efficiency/sensitivity over much of their range. However, the larger cabinet may increase bass output. If we are stating efficiency as +-3dB, this increase in bass output may extend the efficiency range a few hz on the bottom end. This is especially true for in-room (i.e.,, real world) efficiency, which is how we actually experience the speaker.
Generally, we [should] measure efficiency using a standard set of terms, e.g., 96dB/w/m +-3dB from 50hz - 15khz. That is a meaningful set of measurements when comparing one speaker with another. That is not
saying that this set of measurements define how "loud" we perceive a speaker to be. That involves other psychoacoustic effects besides simple measured efficiency.