So riddle me this...say I do ever decide to change out a speaker in one of my amps. Is there an inverse relationship between a speaker's rated power handling and the power output of an amp? In other words, if I put a 15 watt speaker and a 65 watt speaker into a cabinet, and wire them each up individually, will I get more or less output from one versus the other from a 15 watt amp? There are probably other variables that I'm not aware of so let's just assume that all else is equal... My assumption is that a higher rated speaker produces less volume with less wattage flowing to it, which may be obvious, just trying to check my logic I guess.
The wattage rating of a speaker doesn't have much to do with the perceived volume of a speaker. A higher watt speaker can be louder because you can feed more power to it, but from the same amp it's not going to matter. For example...I have two speakers of the same wattage. A G12-65 and a Vintage 30. Both 65 watts. The Vintage 30 is noticeably louder than the G12-65 with all else being same. Same guitar, same amp, same settings, the V30 pumps out more volume. There are many variables like magnet weight, cone design, but the most important variable for loudness is the speaker's sensitivity. Sensitivity is a relative measurement used by manufacturers to comparitively gauge how loud a speaker is at a given wattage and measurement point. This is generally one watt measured at one meter away. If you look at the sensitivity ratings of speakers, you'll see them listed in db. In my example the G12-65 is rated at 96db, the Vintage 30 is 100db. And you can hear that difference.
The Vintage 30 is considerably louder. Sensitivity is not the same as efficiency, but an efficient speaker will have a higher sensitivity rating due to it being more efficient. A speaker's efficiency is generally dependent on how efficiently it turns it's power input into sound instead of heat.
So what does all this mean? It means that speaker wattage doesn't much matter for loudness. The speaker's sensitivity is what matters. And how does sensitivity matter? If you're mixing two different speakers in the same cab, the louder speaker can overpower the speaker with lower sensitivity. Some people don't care, but for me, it drives me crazy. I like to mix speakers, but I make sure the speakers will play nice together.
And of course, the impedances have to match. You have to keep the ohm ratings the same among the speakers.
And lastly, the cab's new wattage rating. When mixing various wattage speakers, your lowest rated speakers determine the wattage handling of the cab. For example, if you have a 2x12 with a Greenback and a Vintage 30, even though the V30 is a 65 watt speaker, the cab's rating will only bee 50 watts. Why? The Greenback is the "weak link" at only 25 watts. You multiply the number of speakers by the lowest speaker's wattage. In this case, 2 speakers x 25 watts (Greenback) = 50 watts.
