Are these speakers comparable + help identify my exact model (Dr Bass vs FearFUL faceoff!)

The LF's lower sensitivity arises because it is tested at lower frequencies [usable bandwidth is 46 Hz - 2 kHz versus 63 Hz - 2.8 kHz*] - it's a typical trade off for woofers as making very large wavelengths is generally less efficient mechanically than making short waves= all things being more or less equal when you go for more ability at the low end of the bandwidth your efficiency is reduced.

*sensitivity is measured in the links you posted as "The average output across the usable frequency range when applying 1W/1m into the nominal impedance. i.e: 2.83V/8Ω...]

 

You kinda answered the question with the Vd spec...the 3012LF moves over TWICE as much air as the 15. That's one reason why so many cab makers use it these days.

 

There will be so much power compression on the 4 ohm driver above ~400 watts that imo both drivers need to be compared at ~400 watts. Much of your Sibway's additional power into the single 4 ohm driver is doing nothing except accelerating damage to the driver.

This helps narrow the gap between the two cabinets considerably.

 

the fEARful cabs do sound great and can get as loud as you need them to be for almost all situations. the lower sensitivity rating means they need more power to get there.

 

Also don't know what your budget is, but you should check out the Mesa Subway 115. Very small, very light, and will get your sensitivity back up (98.5db) while still moving tons of air and having a clear mid voicing.

 

It really depends on your EQ demands. I don't think the 15 will keep pace as you crank up with lows. It will get to its xmax with relatively little power and then make a hash of the rest.

So the question is really how badly have you been abusing the 15 already? Gut feeling is if you haven't been cranking it you would get MOAR from the FF by giving it more loud knob to take advantage of clean power handling.

By the looks of the Kappa chart you would need a wide high mid EQ chop to the FF to get it to mimic the Kappa + Tweeter cab.

 

if you move more air that is more loud, not equivalent. Pushing more power into a more efficient speaker runs away with loudness at low power but piling on the power does not.

 

It is not an apples to apples comparison... The LF version is measured about 1/3rd of an octave lower than its counterpart. If you drive the LF's counterpart with a similar lower bandwidth, at some power level which safe for the LF, the C woofer will get all splodey = zero efficiency. If you limit your input signal to 60-ish Hz or higher per the C version usable bandwidth spec [a HPF will do this and lots of folks use em] then the LF is a less efficient choice, however if you want to have output below 60-ish the LF's counterpart aint tall enough to ride the ride. The ability to yield a strong response very low in the band is something many GB cab users like - if that is your cup of tea is matter for you to decide.